Registered Dietitian Natalie Rizzo evaluates the pros and cons of ketogenic diets for runners.

Ketogenic diets are on the rise among runners who hope to lose weight or teach their bodies to use fat as fuel. But a new study in Nutrition & Metabolism suggests that following a ketogenic diet may actually hinder your athletic performance. So what’s the truth about this diet and why does it have so much hype?

Related: The Beginner’s Guide to the Ketogenic Diet

Contents

What is a ketogenic diet?

For decades, scientists and nutritionists have promoted carbohydrates as the main fuel source for exercise. We know that high carbohydrate diets increase the amount of glycogen stored in the liver and muscle, which improves endurance performance. Yet many athletes and scientists have recognized that the body is full of fat stores, and they wonder if we can tap into those stores for fuel. The major drawback is that it takes longer and requires more energy to utilize fat instead of stored carbohydrates. Still, many scientists are exploring this possibility by feeding athletes a high fat and low carbohydrate diet to observe changes in metabolism and performance.

Recreational athletes are now trying this technique in the hope of burning fat and losing weight. The amount of fat one eats on a ketogenic diet varies, but the range is typically 75 percent fat, 20 percent protein and 5 percent carbs. To put that into perspective, a woman eating 1,800 calories a day would eat 150 grams of fat, 90 grams of protein and 22 grams of carbs. That’s a drastic shift from the typical carb-heavy runners diet.

What does the research say?

A recent study looked at the effects of the ketogenic diet on physical fitness, body composition and fat metabolism in healthy adults. Forty-two healthy people with an average age of 37 followed a ketogenic diet for six weeks. Seventy-two percent of their calories came from fat, 21 percent came from protein and 7 percent was from carbohydrates.

After six weeks, the researchers measured each subject’s exercise performance and found that their oxygen uptake (or aerobic endurance) decreased by 2.4 percent and the individuals became exhausted more quickly. Additionally, their LDL-cholesterol (or “bad cholesterol”) rose by 10.7 percent. Both of those results are bad signs for the ketogenic diet.

Another study examined how these results differed in well-trained athletes. This small study contained eight male subjects with an average age of 28 and at least five years of training experience. For four weeks, the subjects consumed either a ketogenic diet of 70 percent fat, 15 percent protein and 15 percent carbohydrates or a standard diet of 50 percent carbohydrates, 30 percent fats and 20 percent protein.

The athletes on the ketogenic diet actually experienced a decrease in BMI and body fat, compared to those on the standard diet. Interestingly, their aerobic capacity was significantly higher at rest and during low- to moderate-intensity exercise. However, this effect reversed during the final stage of exercise, demonstrating that carbohydrates are the main source of fuel during high intensity workouts.

The bottom line

The jury is still out on the effectiveness of the ketogenic diet. As with many trends in nutrition, the results come down to an athlete’s level of training and ability to follow strict diets. If you decide you want to try this new way of fueling, consult with a registered dietitian first. Remember that fat is higher in calories than carbs or protein–there are nine calories in a gram of fat while there are only four in a gram of carbs or protein, so if you increase your fat intake, you may actually need to eat less. Another fact to consider: saturated fat has been linked to heart disease and high blood pressure, so it’s important to choose fats that are high in unsaturated fat, such as fish, nuts, oils and avocados.

Related:

How I Fueled for Running 19 Miles on a High-Fat Diet

To Keto or to Carb? That is the Question.

Don’t Run on Empty Because of a Low-Carb Diet

Most runners know the long-revered basics of running nutrition: Plan a good pre-race meal, eat a protein and carb-rich recovery meal and hydrate well. Then there are diets, like the popular Ketogenic plan, that promises more energy and weight loss. But is the high-fat, low-carb diet for runners?

Brett Osborn, neurosurgeon and nutrition adviser to nutrition and supplement site BPI Sports says yes. “Endurance athletes in particular will benefit from the Ketogenic diet because during long sporting events, their bodies are running primarily on fats and/or ketones,” he says. “So why not go into the race, for example, already in a robust fat-burning state?”

The Keto diet is a high-fat, low-carb diet where the body is forced into Ketosis, a state where the body doesn’t have enough carbs for energy. Instead, the body starts making ketones, which are used in place of carbs for energy. The diet also burns fat for more energy. Others, however, aren’t convinced the diet is the right choice for runners.

RELATED: Going Green: Are Adaptogens the New Running Fuel?

“I’m going on the record saying Keto is terrible for any serious athlete,” says James Fell, runner, columnist and author of Lose it Right: A Brutally Honest 3-Stage Program to Help You Get Fit and Lose Weight Without Losing Your Mind. “Fat is low combustion fuel. When you are engaged in high-intensity activity, you need rapid access to quick-burning fuel. When you have carbs in your system, you get it,” he added.

Fell says runners can use the Keto diet for lower or moderate intensity workouts, but those longer, harder efforts need carbohydrates. “Fat simply burns too slow, so it’s like trying to suck fuel through a straw and it holds you back from a maximum intensity effort,” he says.

Osborn disagrees. The need for carbohydrates may be a “myth.” The preferred energy source is fat, or ketones, he says. “For eons, marathon runners have carbed-up the night before a race, and for what?” he urges. “Nothing. The primary energy source of the body during a race is fat, so why fill up on carbohydrates?”

If you want to give the Keto diet a try, Osborn says you don’t want to start it a few days before a big race. “An athlete should be burning fat and/or Ketones before the race begins,” he says, suggesting that the diet be started months in advance. “Athletes will not suffer, performance-wise, on the Keto diet.”

RELATED: The Sweet Reasons Behind Allowing Sugar in Our Diets

Another hallmark of the Keto diet is what’s been dubbed “Keto flu,” where you might feel tried or sick as the body adjusts to the new energy source. Those side effects can last between seven to 10 days. “Stick with it even though you may experience fatigue as your body morphs into a fat-burning machine,” Osborn says. “Show your body its newly-preferred energy source.”

Fell, meanwhile, says the Keto diet may be a fad diet, and he suggests runners find a diet that fuels the body and doesn’t cause any gastrointestinal issues. He says it’s not about choosing the perfect diet, “but rather listening to what my body says I need to perform well … Sometimes it’s best to ignore all the dietary hype and go with what makes you feel good, powerful and energized.”

A lot of people suffer from various health problems, such as obesity and diabetes, and the primary culprit is, often than not, the food they eat.

In fact, nutrition has a significant impact on your overall health, period.

As a result, if you eat lots of junk food, then you’ll, eventually, gain weight, become prone to cellular issues, and face a host of trouble.

And you don’t want that.

Enter the Keto Diet

The ketogenic diet is gathering steam like no other diet, and for good reasons.

This nutrition plan has helped lots of people shed weight, improve productivity, get healthier, and so much more.

In today’s post, I’ll explain what the ketogenic diet is, what to eat, what to avoid, and the best way to get started.

So, are you excited?

Then here we go.

The Beginner’s Guide To The Ketogenic Diet

So, what is the keto diet and why is it taking the world by storm?

Also known as low-carb, high–fat (LCHF), the ketogenic diet is a high-fat, moderate protein, low-carb nutrition plan.

By severely limiting carb intake—usually less than 25 net grams per day—the keto diet forces your body into ketosis, which is the purpose of LHCF.

So, what’s ketosis?

Ketosis is, basically, a metabolic state in which the body heavily relies on fat for energy instead of sugar/glycogen.

Chemically, while in ketosis, your body produces ketones by breaking down fat in the liver, then transforming them into energy instead of relying on carbohydrates to generate fuel for everyday function.

In other words, going keto forces your body to burn fat instead of carbohydrates.

You’re Not Starving Yourself

Just don’t get me wrong.

You don’t enter ketosis by starving your body of calories, but you do so by severely reducing carb intake and replacing it with plenty of dietary fats, and a moderate amount of proteins.

When you eat fewer carbs, glucose levels, go down, which lowers insulin levels. This triggers the production of ketones that do not rely on insulin to get into and fuel the body’s cells.

Types of Keto Diets

Since people are different and have different needs and goals, there is also a wide range of keto diets to choose from.

Here are the main ones.

The Standard Ketogenic Diet

Or SKD. This is the most common keto diet that many dieters are familiar with.

The Standard Ketogenic Diet is simple and very effective, especially when it comes to weight loss.

It focuses on:

  • High intake of healthy dietary fats—70 to 80 percent of total calories,
  • Moderate protein—20 to 25 percent—and,
  • Minimal carbohydrates—5 to 10 percent.

This diet is ideal for recreational runners, fitness enthusiasts, or people looking to lose a lot of weight as soon as possible.

The Cyclical Ketogenic Diet

Or CKD. This approach consists of cycling between a typical ketogenic diet, followed by a carb-loading period.

During CKD, you, in essence, you cycle between:

(1) Days of keto dieting during which you consume less than 40 grams of carbs— and

(2) Days of carb-loading during which you consume 400 to 500 grams of carbs to help resupply glycogen stores for prolonged or intense exercise. This phase may last for 24 to 48 hours.

This keto variation is often recommended for serious athletes and bodybuilders.

So, it might not be suitable for everyone.

The Targeted Ketogenic Diet

During the TKT variation, you go keto most of the day, but then consume the total allocated amount of carbohydrates in one sitting, 60 to 90 minutes before a workout.

The targeted ketogenic diet is a compromise between the classic ketogenic diet and a cyclical ketogenic diet, meaning that you can still provide your body with carbs for intense training, but not step out of ketosis.

The purpose of this is to utilize the fuel provided by carbohydrates effectively before it kicks you out of ketosis.

As a general rule, make sure to become keto-adapted first by following a strict ketogenic diet for at least six to eight weeks, before opting for TKD. This ensures that you don’t throw yourself completely out of ketosis during the first few weeks.

During the loading window, opt for carbs that are easily digestible with a high glycemic index.

Then, post workout, up your protein intake to assist with muscle recovery, then consume nothing but keto foods.

TKD is most suitable for beginner or intermediate fitness runners or for those who cannot be on a cyclical keto diet for personal reasons.

You Decide

So which one should you follow?

The answer depends on you. Your own needs and fitness goals should dictate which approach to follow.

But, in general, the standard diet is the way to go—especially if you’re a complete beginner and want to become keto-adapted as soon as possible.

Benefits of Ketogenic Eating

Once you get on the keto path, you’ll realize that it’s more than just another trendy eating plan.

In fact, ketogenic eating is a healthy lifestyle approach that offers a host of benefits.

Here are a few.

Weight Loss

If you’re looking to shed the pounds and keep them off for good, then the keto diet is perfect.

In fact, it’s one of the most effective ways to lose weight in a healthy and sustainable manner.

Since the keto diet helps tap into the fat storage, your body will begin to burn it, leading to weight loss and improvement in body composition.

In other words, your body turns into a fat burning machine.

And it works, as research shows.

Studies have revealed that ketogenic eating outperforms either a typical low-carb diet or calorie-restricted diet for weight loss.

One example is is this research.

During the experiment, participants were given a low-carb, keto diet and a low-fat diet.

After six months, researchers concluded that the low-carb group shed more weight—about 10 pounds—compared to the low-fat group.

For more on weight loss related studies, check this .

Blood Sugar

Research found that when subjects were put on the low-carb diet, they reported reduced appetites.

Further, research has found the keto diet to be super useful for prediabetes people and those with Type II diabetes.

But Why?

Since carb intake is curbed, you’ll limit your body’s production of glucose, which, in turn, keeps sugar levels at bay.

This can help reduce cravings that can lead to binge eating, even without deliberate calorie restriction.

Mental Focus

Ketogenic eating can also increase mental performance.

How?

Two reasons:

Ketones are not only an excellent source of energy for your body, but also a source of fuel for the brain.

When you eat fewer carbs, you also avoid blood sugar spikes, which, in turn, can also improve your focus and mental clarity.

Further, research has also shown that increasing fatty acids consumption can have a positive impact on the brain’s function.

Cholesterol

One common myth associated with the low-carb high-fat diet that it increases cholesterol levels, leading to clogged arteries, heart diseases, and, eventually, death.

Here is the truth.

The myth that dietary fats are the culprit in the rise in cholesterol is just that, a myth.

Most of the recent research conducted on the effects of keto eating has found that it can actually optimize cholesterol levels, and, in reality, improve heart health.

Here is one example:

In a meta-analysis published in the British Journal of Nutrition, researchers looked at the impact of ketogenic diets on important metrics of cardiovascular health, including HDL cholesterol and their findings were quite promising.

In short, the researchers concluded that a low-carb high-fat diet is effective in rising HDL cholesterols —good cholesterol—while reducing LDL—bad cholesterol—levels when compared to standard weight-loss eating plans that preach reducing fat intake.

Other health benefits

I have barely scratched the surface when it comes to the many benefits that keto diet offers.

In fact, studies have now revealed that this diet can fend off against many health ailments.

Some of these issues include:

  • Heart diseases
  • Cancer
  • Brain injuries
  • Epilepsy
  • Alzheimer disease
  • Acne
  • Parkinson disease
  • Polycystic ovary syndrome
  • Etc.

I can go on and on.

For more on that, here are a few sources.

Who Shouldn’t Be on A Keto Diet?

As with any drastic change in dietary habits, there are a few safety issues you need to be mindful of if you’re serious about making it down the ketogenic path.

So, if one of the following cases applies to you, then be extra careful.

  • People on hypo-causing meds such as Insulin, Sulphonylureas, and Glinides
  • People on medications such as high blood pressure.
  • Breastfeeding women
  • People with gallbladder diseases
  • People who have had bariatric surgery
  • Etc.

Also, be sure to discuss with a doctor or a certified nutritionist any significant changes in your eating habits before making it, especially when it comes to super carb-restricted ketogenic diets.

How to Get Started With Ketogenic Eating

The keto approach means a drastic shift in the way you eat, especially if you have never tried any low-carb eating approach.

For that reason, taking your first few steps can be intimidating.

But it’s feasible, none the less, provided that you’re willing to experiment, are motivated, and patient enough.

Here is the good news.

You don’t need (nor should you strive) to know everything there’s about ketogenic eating to get started.

All you need is the basics.

Then, learn as you go, and be willing to make lots of mistakes—that’s, after all, an integral part of the learning process.

So, let’s get down to the keto details.

The ketogenic diet is relatively simple when it comes to the rules to abide by.

The fundamental tenets of ketogenic eating are as follows:

  • Eat Lots of Fats
  • Eat moderate amounts of proteins
  • Eat little carbs

That’s it. No more. No less.

Now, let’s delve a little deeper into these simple (yet elusive) principles.

How to Reach Ketosis?

While you don’t have to enter ketosis as early as possible, most consider doing so as their first successful milestone on the ketogenic path.

But achieving that can take some work and planning. It does not happen overnight, nor it’s just as simple as cutting junk/processed foods.

In general, it can take a few days up to a week of consuming no more than 20 to 30 grams of carbs per day to get into ketosis.

Factors to consider include; your conditioning level, training intensity, body type, and what you’re eating.

Five days is the conservative estimate, according to my experience. But your case might be different.

What to Eat?

Actually, plenty.

This eating approach is by no means a restrictive plan.

But that does not mean you can eat whatever you want—even when it comes to standard healthy foods, such as vegetables and fruits.

Note on Vegetables & Fruits

Eating veggies is an integral part of healthy eating, period.

That said, when it comes to the keto diet, vegetables can be quite tricky.

Sure, veggies are some of the healthiest foods on the planet, but almost all of them contain carbs, in one form/quantity or the other.

That’s something to look out for if you’re serious about reaching a full state of ketosis as soon as possible.

In general, the ketogenic diet includes plenty of leafy green vegetables rich in micronutrients, as well as some of the above-ground veggies, like broccoli, and cauliflower.

Be careful when eating fruits since most score high on the glycemic index. Keto friendly fruits include avocados and berries.

The list

I hope this comprehensive ketogenic friendly food list will help you make the right choices.

What not to eat?

Now that we covered what to eat, let’s look at what you MUST avoid.

As a rule of thumb, when it comes to ketogenic eating, carbs are the enemy.

In fact, it’s virtually impossible to enter a state of ketosis when your body has a supply of glucose to burn.

For that reason, you MUST follow a stringent eating plan, which involves consuming less than 20 to 30 grams of carbohydrates per day.

That means even if your daily required allowance of carbohydrates is 31 grams, you’d still want to stay below 30 grams.

The List

Here is a comprehensive list of foods to be eliminated or severely reduced on a keto eating plan.

  • All grains. Including whole meal (wheat, oats, rye, millet, corn, bulgur, rice, buckwheat, barley, sorghum, amaranths, etc.)
  • Grains products. That include bread, pasta, pizza, crackers, cookies, etc.
  • Sugar and sweets. Mainly table sugar, agave serum, cakes, honey, maple syrup, ice creams, sweet puddings, etc.
  • Sugar-free and low-fat diet products. These tend to be highly processed and may contain many artificial additives that can affect ketone levels.
  • Starches or grains. Mostly wheat-based foods, such as pasta, rice, cereal, etc.
  • Factory farmed fish and pork. These tend to be low in nutrients and high in inflammatory omega 6 fatty acids.
  • Alcohol. Sweet wine, beer, cocktails, etc.
  • Fruits. Except for small portions of avocados and some berries.
  • Tropical fruits. Including mango, pineapple, papaya, banana, etc.
  • Legumes and beans. Such as kidney beans, peas, chickpeas, lentils, etc.
  • Root veggies. Such as carrots, yams, potatoes, sweet potatoes, parsnips, etc.
  • Unhealthy fats. Such as processed vegetable oils, mayonnaise, etc.
  • Refined oils. Including safflower, sunflower, soybean, cottonseed, corn oil, etc.

Pay Attention

Remember that the more you restrict carbohydrates, the faster you’ll enter ketosis.

That said, these extreme restrictions might not be sustainable for everyone.

If you’re a serious runner, logging serious miles every week, then your carb intake might be higher, depending on your training volume and goals.

More on that below.

Getting Your Macros Right

Ok. I have just shared with you a comprehensive list of the foods to eat as well as what to avoid, but how much food should you consume from each major food category?

This is where ketogenic eating can get complicated since it involves calories counting. Yes, there is no way around that.

But it’s not rocket science.

Know your macro ratios.

Macros comprise the primary sources of calories in your diet.

They consist of the following:

  • Carbohydrates
  • Proteins
  • Fats

The majority of your daily calories on a ketogenic diet will come from healthy sources of dietary fats.

Here is the exact macro breakdown of a ketogenic diet:

  • Dietary fats—70 to 75 percent of total calories.
  • Proteins—15 to 20 percent.
  • Carbohydrates—5 to 10 percent.

To put the this into perspective, if you consume 2,800 calories a day, you’d ideally eat:

  • 270 to 300 grams of fat,
  • 105 to 140 grams of protein, and
  • 35 to 70 grams of carbs.

That’s an extreme shift from the typical high-carb that most people are familiar with.

Am I in Ketosis?

The simple way to check whether you’re in ketosis or not is to assess ketone levels in your body.

This can be done using ketone urine test strips, or a blood analysis.

Urine Testing

Urine (acetoacetate) testing is the most common way people measure their level of ketones. This is usually done using ketone strips, such as Ketostics, Urisan, and other urine detection strips.

This method is cheap—thus why it’s so common—costing roughly $10 for 150 strips.

The bad news is, urine testing is not reliable as it only shows excess ketones bodies expelled via acetoacetate, but say nothing about blood ketone levels.

Blood Testing

Blood testing assesses blood ketones—or beta-hydroxybutyrate, or BHB, usually considered a good sign of ketosis and whether your restrictive keto eating is working.

Nevertheless, this method can be quite invasive and expensive over time.

To give you an idea, the monitor used retails at $40, and the test strips cost around $5 each. So, they can be relatively expensive if you intended to measure your ketones on a regular basis.

So, what are some of the other ways of telling you’re in ketosis?

Here is a short list of the ketosis physical symptoms:

  • Changes in mood and alertness.
  • Increased urination.
  • Dry mouth and increased thirst.
  • Sharp and smelly breath.
  • Improved sleep
  • Reduced appetite and hunger.
  • Increased energy and mental focus.

Running Performance and The Ketogenic Diet

One of the concerns many runners have is that keto will negatively impact running performance.

And that’s understandable.

Carbs, after all, are a runner’s best ally. They’re the body’s preferred source of energy. I have stated that in the past and still believe so today.

But what if you want more?

What if you want to drop the carbohydrates and go full keto? Will doing so hurt your performance?

The answer is not black or white.

During the early stages of the keto diet, expect to experience drastic drops in performance.

Once your body has adapted to ketosis (and is using fat as its primary source of energy), your running performance should return to normal.

This, according to most experts, may take up around three to four weeks for your body to adapt to low-carb eating and using fat for fuel.

It took me about six weeks to be able to run normally on a keto diet. It will happen, but you need to stay consistent enough and play the long game.

Running Will Feel Like a Drag—And There is No Way Around it!

Running on keto will suck for the first few weeks. In fact, the first week on the diet will be a nightmare. You’ll feel exhausted every day from the lack of carbs, and the cravings will be, at times, too much to handle.

That’s a part of the process, and a sacrifice you’ll have to make if you’re serious about making it down the keto path.

Be patient. And do not let your ego stand in the way.

During the first few weeks, reduce your weekly mileage, go very slow, and walk, if you have to. Stick with the diet and keep working out.

During this whole time, consume more dietary fats, while keeping your protein intake moderate, drinking plenty of water, and replenishing your electrolytes.

The Research: Keto and endurance

Most of the published studies I’ve come across have found that a keto diet might help with endurance sports.

One example is an experiment in which trained cyclists were put on a ketogenic diet for four weeks.

The conclusion?

The researchers found that aerobic endurance was not compromised at all and that participants muscles mass was the same as when they started.

Further study on professional gymnasts reached similar results.

Here are some links to check out.

When Not To Keto

The only exception where ketosis can hamper performance is in sports that require bursts of explosive power, such as sprinting and powerlifting.

So, if you’re preparing for a race, or logging serious miles every week, then the amount of carbs you can consume and still be in ketosis can be higher than recommended.

In such case, consume 20 to 30 grams of fast-digestible carbohydrates, such as fruit, within 30 to 60 minutes before your workout. This helps ensure that your muscles have the proper amount of glycogen to perform during training.

One Week Sample

Here how a week of eating looks like on the ketogenic diet.

Monday

  • Breakfast:Eggs, bacon, and tomatoes cooked in coconut oil
  • Lunch:Burger with cheddar cheese, guacamole, and nuts.
  • Dinner:Salmon, egg, and mushroom cooked in coconut oil.

Tuesday

  • Breakfast:Egg, basil, avocado, and cheddar cheese omelet.
  • Lunch:Chicken salad with olive oil and avocado.
  • Dinner:Mackerel with asparagus and spinach cooked in butter.

Wednesday

  • Breakfast: Omelet with peppers, broccoli, salsa, and spices.
  • Lunch:Shrimp salad with feta cheese and olive oil.
  • Dinner: Romaine lettuce with low-carb, high-fat dressing

Thursday

  • Breakfast:Cheese omelet with vegetables and avocados.
  • Lunch:Ham and cheese slices with almonds.
  • Dinner:Salad greens with high-fat dressing

Friday

  • Breakfast:Fried eggs with mushrooms and onions.
  • Lunch: Shrimp salad with feta cheese and olive oil.
  • Dinner:Low Carb Salmon Patties

Saturday

  • Breakfast:Eggs, bacon, and tomatoes.
  • Lunch:Four ounces of baked fish with butter sauce
  • Dinner:Steak and eggs with vegetables.

Sunday

  • Breakfast:Coffee with heavy crème
  • Lunch:Burger with cheddar cheese, guacamole, and nuts.
  • Dinner:Three cups shredded cabbage sautéed in butter and onions

Healthy Ketogenic Snacks

In case hunger strikes before one of the main meals, keep it at bay with any of the following options.

  • Cheese with olives
  • Two hard-boiled eggs
  • Strawberries and cream
  • A handful of almonds and nuts.
  • One avocado with pepper and salt
  • Green bean fries
  • Kale chips
  • String cheese
  • Jerky
  • Celery filled with cream cheese
  • Lettuce or cucumber smeared with peanut butter
  • Radishes smeared with butter

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Conclusion

So, should you give the ketogenic diet a try?

I hate to sound like a broken record, but it’s really up to. It depends on you.

So you decided what works the best for you. Just be willing to keep an open mind and experiment.

In the meantime, thank you for reading my post.

Good luck!

Why Low Carb Works for Endurance Athletes

A low carb diet can help you lose weight, but research also shows that a low carb diet may help endurance athletes maximize their performance. Now that it’s the season for all sorts of endurance events (marathons, triathlons, Ironmans and more), I asked Jeff Volek, Ph.D., R.D., an expert on low carb diets for endurance athletes, to tell us why going low carb might improve your performance.

Q: Traditionally endurance athletes rely on high carb diets. You recommend a low carb diet for endurance athletes. Why?

A: A high carb diet locks an athlete into a dependence on glucose as the dominant fuel for exercise. It’s a fact that when we digest and absorb carbs as sugar, the body is forced to prioritize burning that sugar while simultaneously impairing access to and use of fat. Storage of sugar in the body as glycogen is limited to about enough to last one day, or just a couple hours of hard exercise. To prevent this small carb fuel tank from running dry, frequent ingestion of carbs is necessary to prevent a fuel crisis. The strategy of repeatedly shot-gunning sugar-laden gels and drinks to keep the carb furnace stoked is an approach used by many athletes, but it’s worth asking whether this is optimal, healthy, and sustainable. For many athletes, the answer is clearly no.

So how can you break the carb habit and “train” your body to use fat more efficiently? Just performing regular aerobic exercise allows greater amounts of fat to be burned, but this can only go so far. Even the highest caliber endurance athletes will experience dramatically increased fat burning by cutting back on carbs in their diet. We’ve named this process of switching to fat as fuel “keto-adaptation”, and the evidence showing that fat is a premium fuel continues to mount because it is a more efficient source of calories that provides more energy.

Q: How long would it take an endurance athlete to transition from a high carb diet to a low carb diet?

A: Keto-adaptation changes the way your cells use fuel, and this takes time. As your body decreases its dependence on carbs, performance actually decreases during the first couple weeks. But by about four weeks, performance capabilities are back to normal and often exceed previous levels as time passes and adaptation becomes more complete.

Q: How effective is a low carb diet in preventing an endurance athlete from “hitting the wall” during a race?

A: Hitting the wall is an energy crisis in the brain that happens when glucose supply is not able to keep up with demand. As a protective mechanism, the brain signals the body to shut down to preserve any available glucose. It is a catastrophic type fatigue that leaves a profound impact on athletes. You might be thinking that when glucose is limiting, the body can smoothly switch over to tapping its more abundant fat fuel tank. Unfortunately, this doesn’t work like flipping a switch (unless you were previously fat-adapted). Most endurance athletes know this, and they purposefully carry quick energy in the form of sugar to avoid hitting the wall, which is essentially the brain responding to a real-time lack of fuel. It’s ironic that when this fuel crisis hits, the body still has tens of thousands of kilocalories tucked away in fat cells. It’s a bit like being stranded in a boat in mid-ocean and dying of dehydration – just inches away from lots of water, but the wrong kind.

Q: Can you describe a typical day of eating for a high carb endurance athlete vs. a low carb endurance athlete?

A: Most people will find they get the best results eating 50 grams of carbs a day or less. It’s important not to overdo protein on a low carb diet because too much protein can also interfere with ketosis. The best approach is to experiment with finding the right amount of carbs and protein, coupled with regular monitoring of blood (not urine) ketones, which is now available with simple finger-stick instrument. Given that this diet is low in carbs and moderate in protein, the majority of calories need to come from fat, but limit those rich in polyunsaturated fat (e.g., corn, soybean, safflower, cottonseed and peanut oils). And saturated fat is ok. We have repeatedly shown that on a low carb diet, blood levels of saturated fat decrease because a fat-adapted body prefers to burn them as fuel. And finally, a quick comment on salt is warranted. In the fat-adapted body, the kidneys tend to discard more water and salt, which can result in a general “washed-out” feeling. An easy “solution” is to take an extra 1 to 2 grams of sodium per day as broth, bouillon or soup. And, in particular, on days you exercise, be sure to take 1 gram of sodium to prime your circulation 30 minutes before your workout.

Q: Typically endurance athletes “carb load” the night before a race. What does a pre-race meal look like for a low carb athlete?

A: The pre-exercise meal is not nearly as important when you are fat-adapted. Unless the exercise is well beyond a couple hours in duration, most fat-adapted athletes don’t bother with pre-exercise meals.

Q: During races, many endurance athletes supplement with gels and other supplements containing fast-acting carbs to keep their energy levels up during a race. What should endurance athletes on a low carb diet eat during a race?

A: In races, calories are not nearly as important because a fat-adapted athlete is able to use their fat stores for fuel more efficiently. Having said that, many ultra-endurance athletes still trickle in some carbs intermittently (up to 25 grams an hour) during long races and training bouts, but much less than they normally would before being fat-adapted. Many athletes are also using slow-release forms of carbs (oats, chia seeds, non-starchy vegetables, nuts and some fresh fruit, etc.) to minimize the insulin response and not impair fat burning.

Last March, I wrote about an ambitious new study that promised to bring some much-needed data to the contentious debate about the effectiveness of low-carb, high-fat diets—often referred to as LCHF—for endurance athletes. The results have now been published in the Journal of Physiology, and they make interesting reading (the full text is freely available here).

The idea, in a nutshell, is that eating a diet consisting mostly of fat triggers adaptations that make you better at burning fat for energy. Because we all carry around ample stores of fat, transitioning to running on fat effectively solves the fueling problem for endurance athletes, eliminating the risk of bonking and the need to refuel during long races.

Last year, a team at the Australian Institute of Sport led by Louise Burke assembled an impressive group of 21 top race walkers from around the world, many of them headed to the Rio Olympics, and assigned them one or two three-week blocks of intensified training while following one of three carefully controlled diets under strict supervision:

(2) Periodized carb (PCHO): Same overall dietary breakdown, but spread out differently from day to day so that food intake matched the needs of specific training sessions, and with some workouts performed with deliberately low carbohydrate levels in the body. This is in keeping with more recent sports nutrition guidelines, and also incorporates tactics like the “sleep low” approach I wrote about recently.

If you’re interested in the nitty-gritty details of the study, I highly recommend reading the paper. But I’d like to highlight three key points:

Low-carb, high-fat boosts fat oxidation

After three weeks of training on a high-fat diet, the athletes did get dramatically better at burning fat.

Here’s some data on fat versus carb usage during a 25K walk before (white bars) and after (black bars) the three-week interventions. The panel on the left shows carbohydrate usage, and the one on the right shows fat usage. The three groups in graph are high-carb, periodized-carb, and low-carb; data are shown at the beginning, middle, and end of each 25K walk:

Journal of Physiology

For the high-carb and periodized-carb groups, nothing really changes between the before (white bars) and after (black bars) data.

But for the low-carb group, there’s a dramatic difference. The “after” data show a massive decrease in carb usage, balanced by a massive increase in fat usage. In fact, the fat-adapted athletes were able to sustain a fat-burning rate of 1.57 grams of fat per minute, which is 2.5 times greater than their “normal” values.

Low-carb, high-fat hurts efficiency

One of the main criticisms of the LCHF approach is that, while fat stores are more abundant, carbohydrate provides more energy for a given amount of oxygen. That’s a finding that goes back to classic studies from a century ago that found a 5.5- to 8-percent edge for the energy yield of carbohydrate.

No one had tested this critique in a rigorous way, but the new study finds that this is exactly what happens.

Here’s data showing the amount of oxygen needed to sustain 50K race pace for these walkers (white bars are before, black bars are after):

Journal of Physiology

Again, there’s no change for the two high-carb groups. But for the high-fat group, the amount of oxygen needed to sustain this pace gets significantly higher. That’s bad news.

Low-carb, high-fat hurts race performance

Ultimately, as I noted in my previous article on this study, no Olympic medals are awarded for having the most interesting metabolism. What matters is how you perform in competition. The new study tested performance in a series of 10K racewalks:

Journal of Physiology

All three groups increased their VO2max during the three-week period of intense training, so you would expect to see faster races times. And sure enough, both high-carb groups improved, by an average of 190 and 124 seconds, respectively.

In the LCHF group, on the other hand, the gains in VO2max were countered by the decrease in efficiency. The result was no change in race time (they were 23 seconds slower, on average, a difference that wasn’t statistically significant).

So is this, as Burke suggested after an earlier study on fat adaptation, “the nail in the coffin” for LCHF? Almost certainly not.

For one thing, some LCHF proponents argue that it takes much, much longer to fully adapt to a high-fat diet (on the basis of what evidence it’s not clear). As fitness writer Matt Fitzgerald put it after the study was released, “How long does it take to ‘fat adapt’? Apparently, always one week longer than the study proving it sabotages endurance fitness.”

Still, as Burke and her co-authors point out, there may be a difference between Olympic-bound athletes like the ones studied here and recreational ultra-endurance athletes whose goals focus more on completing the distance than sustaining near-threshold intensities or being ready to respond to high-intensity surges from competitors. At lower intensities, the negative effects on efficiency may become irrelevant.

It’s also worth noting that a world-class 50K race walk takes about four hours. What about races that take 10 or 15 hours, where the ability to refuel on the go is a proportionally greater limitation?

In the end, there are still plenty of openings where ketogenic diets might conceivably offer an advantage. But in terms of actual evidence, this study is the best we’ve got so far—and it suggests that switching to fat incurs a measurable efficiency penalty.

***

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The Endurance Training Dilemma – High vs. Low-Carb

Endurance athletes train hard and train often. Regardless of whether you’re an elite competitor or trying to achieve a new personal best, maximizing your recovery and performance with the right nutrition plan is an absolute “no-brainer.” The problem is, with so much conflicting information out there, how can you find the best approach to meet your goals? Traditionally, endurance athletes have focused on high carb diets and gels during exercise to fuel workout performance. However, recently more and more athletes eating low-carb, high fat (LCHF) and ketogenic diets have promoted the use of fat as the ideal fuel source by dramatically reducing carbohydrate intake.

There are experts on both sides of the “low-carb” versus “high-carb” debate, making it a fine line to tread. How are you supposed to determine the best strategy for you? The answer is an individualized approach to your nutrition.

Get Clarity On Your Goals

For elite or professional athletes, the goal is very straight-forward… win. Achieving the best possible performance is the target and nutritional strategies are all geared to achieve that goal. Sometimes, this can be in opposition to promoting health. For example, using large quantities of simple sugars during exercise is a highly effective strategy to maintain high-intensity work output. However, the chronic ingestion of simple sugars over time can have detrimental effects on things like insulin levels, gut health, inflammatory status. For regular folks, is your primary goal to complete a personal best time, or is it equally as important for you to lose weight and improve your health? If the answer is “yes”, then you need a different strategy for how to best fuel your body.

Fueling for Elite Endurance Performance.

Elite level runners and cyclists move fast. They’re working at a very high exercise intensity, and the research is clear, as exercise intensity increase so does the body’s reliance on carbs for fuel (see Figure 8 below). (1)


(adapted from Romijn, J et al. (1))

Stephen Phinney’s research showed that “fat-adapted” ketogenic athletes could burn more fat for fuel than non-keto adapted athletes, however this occurred at low exercise intensities (i.e. 65-70%), not the high intensity of elite competition. (2)


(adapted from Phinney, S et al. (2))

Finally, research from the Canadian Sport Institute highlighted the breakdown of macronutrient utilization during ultra-marathon competitions (100 mile races) by elite levels runners (see Figure 4 below). Researchers found all athletes practiced fueling strategies that maximized carb intake during competition, which is congruent with the contemporary evidence-based recommendations. (3)

Now, there is emerging evidence to show that training in a low-carb or fasted state (i.e. Train Low or Sleep Low strategies) can induce favourable changes in fat metabolism for high level athletes.(4,5,6) The research reveals as little as 5 days of training on a LCHF diet can reboot the muscle and augment fat-burning capacity and this persists despite carbohydrate intake during exercise.(6) Therefore, LCHF can be an effective strategy for elite athletes to employ during specific training days or training blocks to improve performance. However, it’s important to note that chronic low-carb or very-low carb (i.e. a ketogenic diet) intake can reduce pyruvate dehydrogenase in working muscles; an enzyme that’s essential for the effective metabolism of carbohydrates for fuel.(6) Not ideal if performance is your goal.

Fueling for Recreational Performance & Weight Loss

Many of my clients who decide to run a 10k race, marathon, or bike race at a recreational level are doing so to improve their health, lose weight, and connect with like-minded people. When this is their goal, it creates a different “context” from elite performers and requires a different nutritional strategy. For example, it’s not uncommon to see overweight clients, who train months for a marathon or long bike race, fail to lose any body-fat despite logging hours and hours of training.

In this population, the addition of more simple sugars before and/or during training, as well as the consumption of a moderate to high carb diet can easily lead to a caloric excess and chronically elevated insulin levels, inhibiting their capacity to burn fat effectively for fuel. In terms of health, chronically elevated insulin levels can also significantly increase the risk of all chronic diseases. (7)

Rather than using a black or white approach, re-asses your goals and identify your number one priority. If weight loss is your goal, alongside friendly competition, then following the same recommendations given to elite athletes is likely going to be a major roadblock. A lower carbohydrate diet may be your path to success.

If performance is your goal, adopting low-carb feedings prior to specific training bouts or phases may provide benefits, however there is a lack of evidence to show a clear benefit to low-carb fueling during endurance competition. In short, carbs are still king on race day.

In the end, whether you’re an elite endurance performer or recreational enthusiast, tailoring your nutrition approach will yield the greatest results, whichever side of the fence you land on.

Dr. Marc Bubbs ND, CISSN, CSCS

  • A study published in the Journal of the American College of Sports Medicine looked at the effects of a keto diet on exercise efficiency and running speed.
  • During moderate intensity runs, the participants’ exercise efficiency stayed the same as they did when they ate their normal diet. But when they performed more intense runs on the keto diet, it decreased.
  • Their running speed also decreased by 5 percent on the keto diet in comparison to their normal eating plan.

The keto diet is often hyped as an effective weight loss tool, but did you ever wonder what it could do to your running performance? As an endurance athlete, you probably depend on carbs as an easily-accessible energy source for your runs, so what happens to your chances of getting faster or going harder if you limit them?

Related Story

Researchers from New Zealand took on that question, testing the effects of a keto diet on exercise efficiency—how much energy is required to perform work relative to body mass—and speed.

In the study, researchers had a small sample of eight trained endurance athletes follow both a keto diet and their normal diets, which consisted of similar protein levels. When following the keto diet, participants consumed low levels of carbohydrates, and instead got most of their fuel from high-fat meals. Normal diets consisted of around 43 percent carbs and 38 percent fat. On the keto diet, participants only consumed 4 percent carbs and upped their fat intake to 78 percent.

Then, they underwent treadmill stress testing, where they ran to exhaustion.

Researchers found that when the participants followed a keto diet and exercised at less than 60 percent of their VO2 max—the amount of oxygen you can efficiently consume and use—their exercise efficiency remained the same.

But in exercise over 70 percent of VO2 max, their speed and endurance declined. In fact, running speed at VO2 max declined by 5 percent after keto-adaptation—when your body shifts from using carbs to using fat as the primary energy source.

Related Story

This suggests that the keto diet would be just fine for moderate running efforts, but if you want to get faster, or work out at more intense levels, like powering up a hill, it may not be the best diet plan for your goals.

One reason? Fat is a less-efficient fuel source when you are exercising at high aerobic capacity, study author and registered dietitian David Shaw, Ph.D. (c), of the Auckland University of Technology, told Runner’s World. It requires more oxygen to create energy than carbohydrates do. Plus, the fatty acids were not as helpful in producing energy needed for muscle contraction, which may have contributed to the loss of speed.

So, should all runners skip keto? That depends on what your goals are.

“It ultimately depends on how fast you want to go,” Shaw said. For someone wanting to break two hours in a marathon, then a keto diet probably won’t help; rather, it will probably slow you down.

On the other hand, if you simply want to go for a few hours at a low-to-moderate intensity, then you may find that performance can be maintained following a keto diet.

Another possible advantage of a keto diet is that it also reduces reliance on consuming carbohydrates during exercise, meaning that it could be a preferred fueling strategy for some ultra-endurance events where fueling stations are limited, or for individuals who have develop stomach issues when fueling with carbs during racing. You’d want to be sure to test this out well before race day if it’s an option you want to consider.

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The slightly thinner consistency is easy to get down.

Still, because the study was so small, more research needs to be done including more participants to strengthen the findings. Until then, if you are training to improve your PR, you may want to think twice about switching to keto. But if you are just looking to maintain your fitness, or notice that you have issues fueling with carbs during exercise, the diet may work better for you.

Jordan Smith Digital Editor Her love of all things outdoors came from growing up in the Black Hills of South Dakota, and her passion for running was sparked by local elementary school cross-country meets.

Think of this article as a Rorschach test. I’ll describe some data from a recent experiment; you decide for yourself what meaning to extract from it. This, as far as I can tell, is the only safe way to write about low-carb, high-fat (a.k.a. ketogenic) diets for endurance athletes, without getting bogged down in endless debates about your motives, word choice, and sanity. So here goes nothing!

The study in question, newly published in Medicine & Science in Sports & Exercise, comes from a group at the Sports Performance Research Institute New Zealand at Auckland University of Technology, led by doctoral student David Shaw. It’s not a perfect study, but it has some notable strengths compared to a lot of diet-related research: a randomized trial with strict dietary control, and a 31-day period to adjust to the unfamiliar diet. And it tackles a very simple but athletically important question: do you get faster on a ketogenic diet, which is designed to teach your body to rely almost exclusively on fats and ketones (a supplementary fuel that your body produces in the near-absence of carbohydrate)?

Some details: the study started with 10 trained male endurance athletes, all sub-3:30 marathoners running more than 30 miles per week, none with previous experience on a ketogenic diet. Two of them failed to stick to the study’s conditions, so the final analysis includes 8 subjects. All of the subjects, in randomized order, completed two 31-day protocols: one consuming their normal diets, the other on a ketogenic diet, with a series of performance and physiological tests before and after each 31-day block.

The normal diets for these particular people averaged 42.9 percent carbohydrate, 38.5 percent fat, and 18.6 percent protein. The prescribed targets for the ketogenic diet were less than 50 grams per day of carbohydrate, 15 to 20 percent of calories from protein, and 75 to 80 percent from fat. The subjects were given free coconut oil, olive oil, LCHF cereal, and discounted fruits and vegetables, and their dietary reports were carefully monitored. They ended up averaging 34 grams of carbohydrate per day (4.1 percent of their calories), with 77.7 percent of their calories from fat and 18.2 percent from protein. Regular blood and urine tests confirmed that the subjects were indeed consistently in ketosis.

There were two basic assessments. One was a progressively accelerating treadmill test, which allowed the researchers to measure VO2max at exhaustion, and also to assess efficiency at a range of different speeds as the treadmill accelerated. The other was a plain old run to exhaustion at pace equivalent to 70 percent of VO2max, which the subjects could maintain on average for about four hours (so, in other words, significantly slower than marathon pace, which is typically somewhere around 80 percent of VO2max). During the run to exhaustion, they either received a carbohydrate-based sports drink (during the normal diet trial) or an artificially sweetened drink with the same number of calories from coconut oil (during the ketogenic trial).

In the efficiency test, there was no difference between the diets at the lower speeds corresponding to below about 60 percent of VO2max. Once the pace picked up to above 70 percent of VO2max, however, the runners on the ketogenic diet became significantly less efficient: they needed more oxygen and more energy to sustain a given pace. Their VO2max itself—that is, the maximum amount of oxygen they could use per minute—stayed the same on both diets, but the speed they could run at while consuming that oxygen was lower on the ketogenic diet.

Interestingly, that echoes what Kieran Clarke, the co-developer of the ketone ester drink sold by HVMN, told me last year: “As soon as you’re up to 75 percent of your maximum workload,” she said, “I wouldn’t even go near a ketone.”

That makes the run to exhaustion extra-interesting, because it was at 70 percent of VO2max, right around the threshold where efficiency seems to start suffering. So here’s the Rorschach part of the article. On the left, you’ve got the before-and-after results for each of the eight subjects on their habitual diet (plus the average results with standard deviations shown); on the right, the same thing for the 31-day ketogenic diet.

(Photo: Courtesy Medicine & Science in Sports & Exercise)

So what’s the verdict? The statistical analysis tells us that time to exhaustion was similar in both conditions: the average times before and after the ketogenic diet were 239 and 219 minutes, respectively, with a p value of 0.36. Three of the subjects lasted longer; five gave up sooner. The variation is much higher than after the habitual diet: some seem to have thrived, others tanked.

The big question is how much we can or should read into those results. Would the three people who got better have shown similar results in another test a week later? A month later? How about the five people who got worse? Or is it just random scatter, since time-to-exhaustion tests are very sensitive to small perturbations in how you’re feeling?

The researchers offer one speculative answer to this question. You can divide the subjects into two groups based on their respiratory exchange ratio (RER) at the end of the VO2max test. The RER is the ratio between exhaled carbon dioxide and inhaled oxygen, and (with a few caveats) it tells you what mix of fat and carbohydrate you’re burning: a value of 0.7 corresponds to pure fat, 1.0 corresponds to pure carbohydrate, and greater than 1.0 suggests you’re going so hard that you can’t supply oxygen quickly enough and are adding a significant amount of anaerobic energy.

After 31 days of ketogenic diet, all the subjects had ramped up their fat-burning abilities (which is good), but had also lost some of their carbohydrate burning abilities (which is not good, particularly at near-maximal intensities where you’re consuming energy very rapidly). In their post-keto VO2max test, 4 of the subjects had a final RER above 1.0, suggesting that they could still access carbohydrate and anaerobic energy at a reasonable rate, while the other 4 had a final RER below 1.0. Those with the lower RER were the ones who subsequently struggled in the time-to-exhaustion test: their average time decreased significantly by 237 to 174 minutes, and they had higher lactate levels at the end of the test. In contrast, those with the higher RER had lower lactate levels and no significant change in time to exhaustion (increasing from 241 to 265 minutes).

Again, this is a highly speculative suggestion. The interpretation of RER at high intensities is problematic, and combing through post-hoc sub-groups of 4 people is a good way of finding patterns that don’t really exist. But it’s an idea to file away for future investigation: could a simple measurement of RER at VO2max give you a quick and reliable way of predicting who’s likely to perform well or poorly once they’ve adjusted to a ketogenic diet?

One final historical note: it’s interesting to see how many echoes there are here from Stephen Phinney’s 1983 paper on four weeks of ketogenic diet for cyclists, which has near-scriptural status in the ketogenic community. In Phinney’s study, fat-burning was ramped up but high-intensity power was throttled: he noted “a severe restriction on the ability of subjects to do anaerobic work.” In a time-to-exhaustion test, there was no significant change on average (147 to 151 minutes), but huge individual variations: one of the five subjects improved from 148 to 232 minutes, another decreased from 140 to 89 minutes. Shaw’s new results seem surprisingly similar.

To sum up the key points from the inkblot: at speeds faster than 70 percent of VO2max (i.e. well below marathon pace), efficiency was significantly impaired on a ketogenic diet. At speeds slower than 60 percent of VO2max, efficiency was unchanged. Right at 70 percent VO2max, time to exhaustion was unchanged on average—but the individual results in the graph above suggest the possibility of a more nuanced picture. You can decide which dot you think you’d be.

My new book, Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance, with a foreword by Malcolm Gladwell, is now available. For more, join me on Twitter and Facebook, and sign up for the Sweat Science email newsletter.

Filed To: DietScienceAthletesRunning Lead Photo: Andi Frank

Keto and Running: Is the Low-Carb Ketogenic Diet for Runners?

Many runners are curious about the ketogenic diet because the promises are alluring. But does keto and running work together? What are the drawbacks?

Before anybody decides to jump on the keto bandwagon and abandon carbohydrates, they should seriously consider whether this diet is right for them.

Because while most folks are aware of the benefits, few fully understand the drawbacks. And most importantly, the sacrifices that are needed to adhere to such a restrictive diet.

After all, the Ketogenic Diet meets Matt Fitzgerald‘s definition of a ‘diet cult:’

A diet cult is any diet that is based on the false idea that there’s a single ideal diet for humans. The underlying essence is that false belief that this diet is better than any other or even the only right way for anyone to eat.

As the world’s most prolific omnivores, humans are uniquely evolved to eat a wide variety of foods – and thrive. There’s virtually no reason to abandon such a powerful adaptation.

To determine if keto and running are a match made in heaven, we have to answer some questions:

  • What does it take to truly adhere to the ketogenic diet?
  • Are there drawbacks to removing almost all carbohydrate from your diet?
  • How sustainable is the diet in the long-term?
  • Can some elements of keto be used without strictly adhering to the diet?

First, let’s get a good working definition of the ketogenic diet.

What is the Ketogenic Diet?

At its simplest, Keto is a high-fat, adequate protein, and extremely low-carbohydrate diet. It’s similar to the Atkin’s Diet and other low-carb diets with the exception that you need to be in ketosis to properly adhere to the diet.

Wikipedia has a great explanation of how this works:

The diet forces the body to burn fats rather than carbohydrates. Normally, the carbohydrates contained in food are converted into glucose, which is then transported around the body and is particularly important in fueling brain function.

However, if little carbohydrate remains in the diet, the liver converts fat into fatty acids and ketone bodies. The ketone bodies pass into the brain and replace glucose as an energy source.

The production of ketones signifies that an individual is in ketosis. And to remain in ketosis, carbohydrate intake needs to be less than 50g per day. That means most runners favorite foods are mostly off limits, like:

  • Fruit (!)
  • Legumes / lentils / beans
  • Bread and other whole-grain foods
  • Starchy vegetables like sweet potatoes and beets
  • Alcohol 🙁
  • Many sauces and marinades that are high in sugar

As you can see, your diet will most likely need a complete overhaul if you decide that keto is for you.

And there are certainly drawbacks. Potential side effects may include constipation, high cholesterol, acidosis, or kidney stones.

Is There Evidence that Keto and Running Mix?

Some runners have seen tremendous success with the ketogenic diet. But we shouldn’t rely on outliers…

Zach Bitter is a famous case study of a runner who eats keto. But there are some caveats:

  • He’s been doing it since 2011 (it takes a long time to become fat-adapted)
  • His diet is not strictly keto (he cycles between ketosis and simply low-carb)
  • As a pro runner, he has enough time for the Ketogenic Diet (it’s more of a hassle)
  • He focuses on ultramarathons (fat as fuel makes more sense the longer the race)

These are very important considerations! Because if you don’t have the time, patience, and discipline for the Ketogenic Diet, then you won’t get any of the benefits.

Moreover, any runner training for “normal distances” (say, the marathon or any shorter race) is going to want access to carbohydrates for fuel. They’re limited but they’re more powerful for faster racing. This is addressed in more detail in this conversation with a dietitian.

The higher intensity the race, the more you’ll need carbs (rocket fuel) rather than fat (solar energy).

What About Low-Carb Tour de France Cyclists?

There’s been a lot of focus on the last few years of the Tour de France because some cyclists have reportedly been eating a Ketogenic Diet.

For a race that lasts thousands of miles over weeks, it’s also an event that lends itself to fat-adapted athletes. Most mortals are not cycling 100+ miles every day for the better part of a month…

But even so, these cyclists are not actually eating a strict Keto diet. They’re periodizing their diets to strategically get some of the benefits of eating low-carb without the problem of not having enough fuel for higher-intensity cycling.

Ketone supplementation is also happening, but this is being done without adhering to the Keto diet.

Clearly, it’s important to understand the nuances of elite athletes’ diets and refrain from copying them exactly.

But it’s apparent that some aspect of periodized nutrition or carb cycling can be helpful. But which tweaks will help your performances?

Keto Tweaks That Might Work

As long as you never need a big burst of energy, you’ll thrive eating keto. But bursts of energy are what we do as runners!

Just think…

  • Anaerobic workouts require high-intensity running
  • Races at the marathon distance or shorter require bursts of energy
  • Mid-race surges are, by definition, bursts of energy

If you’re relying on the Ketogenic Diet, your performances will suffer if you’re trying to run fast.

But there are some elements of the diet that could help runners:

  • Running morning runs on an empty stomach to improve fat burning capabilities
  • Cycling through low- and high-carb weeks depending on the training
  • Supplementing with exogenous ketones (this is a good option)

Ultimately, only highly dedicated runners training for ultramarathons ought to be thinking about the Keto Diet.

Other runners will have trouble sticking with the diet, the adaptation timeframe will hamper weeks of training, and the intensity of shorter races means that carbs are necessary to reach your potential.

Instead, a diet optimized for running has the potential to boost your recovery and performances.

How to Eat for Endurance the Right Way

The vast majority of runners will thrive with the body’s preferred fuel source for high-intensity exercise: carbohydrates.

But don’t take my word for it. I’ve talked to some of the brightest Registered Dietitians about optimal fueling for runners, like:

  • Nancy Clark, arguably the most famous RD in the world, and author of The Sports Nutrition Guidebook
  • Annyck Besso, RD
  • Anne Mauney MPH, RD (my partner on our Nutrition for Runners program)
  • Lauren Kort MS, RD (a national award winner)
  • Kristina LaRue, RD, CSSD, LDN
  • Lauren Trocchio, RD, CSSD, CSOWM, LD
  • Heather Caplan, RD
  • Lindsey McCoy, RD, CSSD, LD

These nutrition experts:

  • Have advanced degrees and certifications in nutrition
  • Advise Olympians at the world-class level
  • Appear on television as thought leaders in the diet space
  • Consult with pro sports teams like the Boston Red Sox and Orlando Magic

I’ve always said that if you’re going to model your behavior after someone, model it after the best. None of them believe that keto and running are a practical combination.

They all recommend a balanced diet, rather than a diet that ignores an entire macronutrient. That’s because a well-rounded diet works best for endurance runners!

To help you optimize your diet for running, sign up here and I’ll send you two bonus podcast episodes with Anne Mauney, RD on fueling and nutrition Q&A. We dive deep into your nutrition questions so you can focus on training.

I’ll also send you our Registered Dietitian-approved shopping list to make picking out healthy foods at the grocery store even easier!

Is a Low-Carb Keto Diet Better for Endurance Athletes?

Take Nicole Kalogeropoulos and fiancé Zach Bitter, Altra athletes currently training for the 100-mile Western States Endurance Run. The couple follows a low-carb keto diet rich in eggs, salmon, and nuts. More surprisingly, they say the low-carb life has improved their performance. (Considering the diet? Try this keto meal plan for beginners.)

“Since I’ve been more committed to a high-fat diet, I’ve been able to recover faster, allowing me to train at a higher level consistently,” says Kalogeropolous. “Plus, I don’t need to take in as much food during races, and I have fewer stomach issues than I did on a higher-carb diet.”

But wait, aren’t endurance athletes supposed to load up on pasta before a big race, then suffer through sugary energy gels every few miles to keep their energy up?

Apparently, only if your body is stuck in a sugar-dependent state. “A high-carbohydrate diet locks you into a cycle of dependency on glucose because carbs force your body to burn sugar instead of fat,” says Jeff Volek, Ph.D., R.D., a professor of human sciences at The Ohio State University who studies ketosis extensively. And since your body’s sugar stores can only fuel you through a couple hours of intense exercise, you’re stuck continuously consuming carbs to keep your energy up, he explains.

Break this cycle, and your body will use fat-a more efficient source of energy-as fuel instead, which should theoretically translate to less dependence on sugary gels and chews during an endurance race, and possibly more energy. (P.S. Here’s your start-to-finish guide to fueling for a half marathon.)

Even better, ketosis could help you avoid hitting the dreaded “wall” toward the end of a long run or bike ride. That’s because blood ketones, which fuel your brain just as much as your body, don’t sharply decline in the brain the same way glucose does, so your energy levels and mood stay much more stable. “Ketones have been shown to offer remarkable protection from the signs and symptoms of low blood sugar,” says Volek.

Bitter has seen this in practice during his runs and races. He started following a low-carb Atkins diet in 2011, and though he felt a little lethargic at first (this is normal as your body adjusts to using fat as its new energy source), he doesn’t need to fuel as much during events-yet he feels better. “I fuel less for the same energy level, recover faster, and sleep more soundly,” he says. (See also: I Tried the Keto Diet and Lost More Weight Than I Expected To)

It sounds counterintuitive since you’ve been told that carbs are everything when it comes to endurance-but this age-old suggestion is actually based on limited research. As Volek explains in a European Journal of Sport Science review, there’s only been one placebo-controlled study on the subject, and it didn’t show any performance benefit to loading up on carbs leading up to an endurance event.

That said, there are some things to consider before adopting a keto diet for your next marathon. Check out the things to know about exercising on the keto diet, and keep these low-carb tips in mind before trying it yourself.

Load up on electrolytes.

“The fat-adapted body tends to discard more salt,” says Volek. To up your sodium intake, he suggests consuming a couple cups of broth every day and making sure you don’t choose no-sodium versions of foods, like nuts. Bitter also takes electrolyte supplements during his ultras. (More: How to Stay Hydrated When Training for an Endurance Race)

Start in your off-season.

Don’t switch things up right before a race. “The process of keto adaptation fundamentally changes the way your cells use fuel-and that takes time,” says Volek. This means you might notice a dip in performance during the first couple weeks, as your body becomes less dependent on carbs. But you should start to feel better within a month as your body adjusts.

Figure out what works for you.

“Just as we all won’t get the same results from a workout, it’s impossible to make a generalization about what eating plan will benefit everyone,” says Silverman.

Even Kalogeropolous and Bitter have different approaches to the same goal: Bitter monitors his ketone levels with blood strips and follows a program he calls “periodizing carb intake based on lifestyle.” He nearly eliminates carbs when he’s recovering or training lightly, then follows a diet of about 10 percent carbs when training at peak volume, and 20 to 30 percent when training at his highest volume and intensity. (Learn more about carb cycling.)

Kalogeropoulos is a little more flexible. “I eat a low-carb diet, but I’m not always so regimented since I travel so much for work,” she says. “Following a specific plan is less important than paying attention to how I feel.”

  • By Kiera Carter

Will Running on the Ketogenic Diet Improve Performance?

The notion that your body can literally run on fat, rather than carbohydrates, is an attractive one.

The ketogenic diet has gained momentum (like with the 28 day Keto Challenge) in recent years, with ultra athletes like Western States 100 winner Timothy Olson lauding the benefits of the high-fat regime.

Just because you can go keto, though, doesn’t mean you should.

We examined the latest research and chatted with registered dietitian Cara Harbstreet to give you the cost-benefit analysis of running on the ketogenic diet.

What is ketosis?

In the average diet, carbohydrates supply glucose that the body uses for energy. Ketosis is a metabolic state in which the body doesn’t have carbs to burn, so it turns to ketone bodies—fatty acids made in the liver—for energy instead.

“The metabolic shift occurs as the body becomes more efficient at burning fat,” Harbstreet says.

She notes that as the body becomes adapted to burning fat, it becomes less adapted to burning carbs. “You have to stay committed to the diet long enough to achieve stable ketosis,” she says.

“If a person is bouncing in and out of ketosis, you don’t quite achieve that metabolic efficiency, and performance can suffer.”

The advantage to ketosis, though, is simple. The body can only store 2,000 to 2,500 calories worth of carbohydrates, but each pound of fat we carry represents about 3,500 calories of energy. In other words, you carry more energy in a pound of fat than in an entire fuel belt’s worth of gels and goos.

Exercises is the best way to boost energy. Use Aaptiv to start your fitness regimen.

How does your body burn carbs versus fat?

The problem with the ketogenic diet for runners is that the body burns carbohydrates and fats quite differently. As leading fat researcher Louise Burke writes in Sports Nutrition: More Than Just Calories,

“Fat oxidation (burning) is inhibited at exercise intensities above 75 percent of maximum aerobic capacity.”

Anything over 75 percent of max effort and the body switches to burning carbs because the fat oxidation process—fat mobilization, glucose breakdown, and glycolysis—takes more time than the body can sustain an intense effort.

For example, if you’re running a 5K at 90 percent of aerobic capacity, you’ll finish before your body has a chance to use onboard fat stores as energy. This is true no matter how fast you run.

Even elite marathoners can’t really use fat as fuel. Running sub-three hours puts most humans above 75 percent of VO2 max.

However, ultramarathoners and marathoners whose pace doesn’t exceed 75 percent of VO2 max can burn fat as a primary source of fuel rather efficiently while in ketosis.

In a 2015 study by Ohio State University fat researcher Jeff Volek, elite endurance athletes on diets of 10 percent carbohydrates, 19 percent protein, and 70 percent fat burned fat more than twice as efficiently than elite high-carb runners.

That said, Volek’s study and similar experiments have yet to find a performance benefit from ketogenic diets. Ultra athletes like Olson prefer them because fattier fuel can make you feel fuller and prevent sugar highs and crashes, but as far as we know, they don’t make you any faster.

What can make you faster? Aaptiv classes. Check them out here.

Which runners can benefit?

First off, you need to run really far in order to avoid a negative outcome. You’re essentially starving your running body of its primary energy source after all.

“Carbohydrates are just the most efficient source of fuel, especially for endurance athletes like runners,” Harbstreet says. “You’re essentially using your glycogen, stored as glucose until those stores are depleted over one or two hours of exercise.”

So, in order to kick your fat burners into gear, you need to run for a while—and not exceed 75 percent of aerobic capacity. But to get that far, you’ll need to put your body into a ketosis, and that doesn’t happen overnight.

In Volek’s study, the elite endurance athletes on ketogenic diets restricted carbs for at least six months before the test. Although you can reach ketosis in less time, ketones expert Ken Ford told Outside “nothing good happens in five days.”

What’s more, you’ll need to be strict to maintain a low carb and moderate protein consumption. “For the average person, you would be drastically changing your day-to-day routine,” Harbstreet says.

“Many people mistakenly believe they’re following a ketogenic diet; a true ketogenic diet is 5 percent total calories from carbohydrates.”

So should you try it? Well, be honest about your commitment to a low-carb diet and the time and duration of your runs. There’s no shame in not being an elite athlete.

You also don’t need to be an elite athlete athlete to get in a good workout. It’s easy to do Aaptiv classes.

Is The Ketogenic Diet Good For Endurance Athletes

Is The Ketogenic Diet Good For Endurance Athletes? EndurElite Chief Endurance Officer Matt Mosman and Chief Science Officer Jordan Joy discuss the pros and cons of this diet for runners, cyclists, OCR, And other endurance athletes?

Some of the ideas and concepts discussed in the video are articulated in greater detail and with greater specificity here.

Video Transcription:

Is Keto Diet Good For Runners, Cyclists, OCR, And Other Endurance Athletes?

Matt: Good morning, Family of Fast. Matt Mosman, the Chief Endurance Officer over at EndurElite. Today, we’re going to be talking about a hot topic, and that is the ketogenic diet. More specifically, we’re going to discuss what the ketogenic diet is, what happens from a metabolic perspective with the ketogenic diet, if it’s a good fit for endurance athletes, and we’re gonna cover some other random topics about the ketogenic diet.
Now, I’m no ketogenic expert, but I had an idea this morning where I could find one. So I headed down to the gym, and I looked for the biggest, baddest bro dad. And they’re really, really easy to spot. They have really shaggy beards, broad shoulders, and meaty arms. And I found this guy right here. And I was like, “Dude, I will give you a five-pound tub of protein, if you tell me a little bit about the ketogenic diet.” And to these guys, it’s, like, pure gold.
But all kidding aside, this is your first chance to meet my partner at EndurElite and the EndurElite Chief Science Officer, Jordan Joy. Now, Jordan Joy has his Ph.D. in nutrition, super smart guy and a ketogenic expert. So the information you’re gonna hear from him is gonna be true. It’s gonna be accurate. And it’s not gonna be the usual bro science bullshit you usually hear about the ketogenic diet. So without further ado, let’s just hop into it. All right, Jordan, explain to us what the ketogenic diet is.

What Is The Ketogenic Diet?

Jordan: Little-known fact, I’m actually Matt’s bodyguard, but he does pay me in protein. So that part is accurate. Now, the ketogenic diet, it’s any diet that actually induces ketosis or elevates blood ketones through a nutritional process that’s not starvation, which would be the other kind of ketosis. And then the third kind of ketosis would be metabolic ketoacidosis. And all these are very distinct things. So when we talk about a ketogenic diet, we’re talking about nutritional ketosis, which is high fat, low carbohydrate, moderate protein.

What Food Is Included On A Ketogenic Diet?

Matt: So what kind of foods do people on a ketogenic diet typically eat, or what’s some standard foods?
Jordan: Bacon.
Matt: Bacon. Love me some bacon.
Jordan: Some of the most popular foods, bacon, really meats in general, dairy. We still eat vegetables. That’s a little bit of a myth that vegetables are not eaten. Avocados are a big deal. I recommend to everybody that starts a ketogenic diet to eat an avocado every day just for the fiber content. It’s the easiest way to get it. Coconuts, nuts. I eat a ton of peanut butter. Yeah, that about covers it.

What Is The Macro-Nutrient Breakdown Of A Ketogenic Diet?

Matt: Very nice. So what does the macro-nutrient breakdown look on a ketogenic diet from your fats to carbohydrates to protein?
Jordan: Okay. So within the nutritional ketogenic realm, we’re talking about nutritional ketosis. We are looking to elevate blood ketones by manipulating our diet in a certain way. So there’s different types of ketogenic diet that you could be consuming. And that could be the therapeutic ketogenic diet or just, kind of, the origins of this way of eating, where we’re inducing ketosis for a nutritional purpose that helps to treat some sort of disease, most popularly, epilepsy. The most accepted use of the diet is for treatment of epilepsy seizures. It’s been more commonly accepted for treating diabetes, less so for heart disease but that’s emerging, cancer, for certain types of cancer. And in these types of diets, we’re looking at, like, really, really high fact in some cases and sometimes 90%, 95%. And it, kinda, depends on the individual. So when we’re talking about epilepsy, for example, somebody might stave off their seizures with an 80%, 85% fat diet with 5%, 10%, 15% protein.
For people that it’s harder to treat, they may be on a super high fat, pretty low protein diet and almost no carbohydrate whatsoever. And then when you’re talking about the average person, we’re talking about at least 70% fat and 20% to 25% calories as protein and 5% to 10% as carbohydrate. And we’re gonna talk about something today that is a little bit more liberal. For an athlete’s ketogenic diet, which is at this current stage, a little bit poorly defined, but athletes need a little bit more carbohydrate. And you can actually maintain ketosis eating 200, 300 grams of carbs a day. So we’ll talk about that a little bit later in the video.
Matt: Awesome. Okay. So basically, the breakdown is 70% fat, 20% protein, and 10% carb in a nutshell or pretty close to it.
Jordan: Yes, usually 70-25-10, or sorry, 70-20-10 or 70-25-5, or sometimes even 80-15-5, common.

Metabolism On A Ketogenic Diet

Matt: Cool. So the main thing is high fat, low carb, simply put. So let’s talk about a little bit what happens from the metabolic aspect with the ketogenic diet. Now, as endurance athletes, a lot of us are on a higher carbohydrate diet, and we get our energy from glucose and glycogen, but when you’re on a ketogenic diet, things happen a little bit differently. The ketogenic diet relies more on free fatty acids to produce energy. So, explain, kinda, what happens from a metabolic perspective on the ketogenic diet that’s specific to, like, endurance athlete energy demands.
Jordan: Yeah. When we are taught energy metabolism, we’re always taught that it’s glycolysis. And that’s true when it’s anaerobic. And that’s what, you know, when you feel lactic acid that’s anaerobic metabolism, end product’s lactic acid. When we go through aerobic metabolism, which is the most common, most prevalent type of metabolism for endurance-based exercise long-duration events, you can still derive energy form carbohydrates through first the anaerobic glycolytic pathway. And then it goes into what’s called the Krebs cycle. When you are talking about ketogenic metabolism we’re almost exclusively talking about aerobic metabolism to get in to the Krebs cycle and produce energy. Now, when we’re going through anaerobic metabolism, we generate 4 ATP. And when we’re going through aerobic metabolism, we’re generating more like 34, 36 ATP.
Matt: Got you. Okay. So what are the main fuel sources? What happens when the free fatty acids are broken down before they go into the Krebs cycle? There’s two basically ketone cells that are made, correct?
Jordan: Mm-hmm. So when we’re going through the aerobic metabolism, there’s an entry point that you go through, and it’s called acetyl-CoA. And you get that from either anaerobic or aerobic routes. When we’re having fat come in, we’re taking these big long chains of fats several carbons long, 16, 18, 20 carbons, and they come in to…they want to become acetyl-CoA in order to get into this cycle.
What happens, we have a buildup of what are called ketones, beta-hydroxybutyrate or acetoacetate. What happens when they’re coming into the cycle is there’s not enough room for them to get in. We can’t generate enough acetyl-CoA from these fats. So we end up with an accumulation of these two-carbon to four-carbon molecules. And then they get released from the mitochondria for release from the cell. And they can enter the bloodstream because that’s when they’re small enough to actually exit the cell.

Does A Ketogenic Diet Work Well For High Intensity Endurance Exercise?

Matt: Got you. So a couple of points here, and this is a question I ask, Jordan, all the time, where do you think that threshold is where your body is able to utilize the fats from the ketogenic diet before it starts to shift to more anaerobic glycolysis, which can only use carbohydrates? I mean, what’s, kind of, that inflection point? Does it differ between people? And then how do you accommodate for that? Like, if you’re on a ketogenic diet and say you’re gonna go do some interval training and it’s gonna be, you know, 85% to 90% of your max heart rate, obviously, your body’s not gonna be able to burn fat. It wants to do carbs or glucose, glycogen. So what happens then, when you’re on a ketogenic diet?
Jordan: You feel flat and a little bit lethargic, like you’re out of energy pretty much. I’m sure we’ve all felt that way before, but when we’re talking about, like, the spectrum of exercise, we have very short events. So if you’re doing just, like, a 40-meter sprint, if you just do one of those on the ketogenic diet, you probably won’t feel any different because you have enough glycogen stored up. You can still access it. As long as you’re exercising regularly, you’re still accessing glycogen. You don’t really forget how to use it. And then when you’re in a little bit longer, like, 3 minutes or 30 seconds to 2 minutes, you’re gonna…when you’re doing intervals, for example, you’ll definitely feel fatigued. And then even during the longer events, I think, even up to, like, marathon distance, if you’re a very high-level athlete, I think you would feel impeded on a strict ketogenic diet, not the athlete’s ketogenic diet, which is yet to be explored thoroughly, but then after a marathon a distance I think is when you would start to possibly experience benefits of a ketogenic diet.

Is A Ketogenic Diet Beneficial For Ultra Endurance Athletes

Matt: So it sounds like the ketogenic diet is for endurance athletes. You know, most of the people in the EndurElite Family of Fast are, kinda, long duration endurance athletes. So they’re racing for more than, like, 30 minutes and, you know, up to 6, 7, 8 hours. So it sounds like to me, and I’m gonna make a couple points here, the ketogenic diet may be more beneficial the longer the event and maybe the lower intensity type events. Is that correct in my thinking?
Jordan: That is correct.
Matt: So what does a person need to do say if they’re doing a 5K, that’s pretty short and intense, they’re on a ketogenic diet, what can they do to make sure they have the energy to run their fastest?
Jordan: Yeah. So 5K, if you’re running at a high level, you’re gonna be under 20 minutes, for sure. So if you just have enough carbohydrate before that event, I think that you would actually be okay.

Can You Have Carbs On A Ketogenic Diet

Matt: And I think that’s where a lot of people get confused is, like, on a ketogenic diet, like, you don’t allow any carbs, but in this case, what Jordan is talking about, it’s pretty beneficial, like, just to load up on carbs before a 5K, before you go to the race. And then you can go back to a higher fat…well, stick with the regular diet. Just introduce carbs before a race, correct?
Jordan: Yeah. And there’s actually, like, a… When we talk about carbohydrate periodization, we have an article up on EndurElite right now talks about this. If you supply…and these people are not on a ketogenic diet, but if you supply carbohydrate before high-intensity events, and then restrict it for low-intensity long duration events, you actually have greater metabolic adaptation. So a ketogenic diet, I think, it’s just a tool, all right? A ketogenic diet is a tool to adapt your metabolism to different types of stress.
So even if you are a very high-level competitive athlete, you’re gonna be carbohydrate-based throughout the season, maybe during the off-season, you go ketogenic for a couple months. And you just, kind of, force your metabolism to adapt for a little bit, it’s not going to impact your performance negatively during the season because you’re not on that type of diet, but perhaps you have greater capacity for fat oxidation or you can use fats a little bit higher intensity, generate a little bit less lactic acid, make your fuel sources last a little bit longer, and overall just become a better athlete.

Ketogenic Vs. A High Carb Diet

Matt: Makes perfect sense. So let’s, kind of, move onto the next topic. And I want to make one point here. On a high carbohydrate diet as an endurance athlete, your body has about anywhere from 400 to 1,000 grams of glycogen stored in the muscle and depending on what type of athlete you are, which you’ll draw on during these longer events, and that supplies the energy, but it’s a limited supply. And that’s why you have to replace through a carbohydrate supplementation during exercise to keep blood glucose levels elevated to have that energy to keep on going. So what’s really interesting is, like, with the ketogenic diet and being able to utilize fats, it almost represents an unlimited energy source. Would you agree with that?
Jordan: Yeah. It’s virtually unlimited. You can store, even a lean person, 70,000 calories. So you’re probably not gonna run out.
Matt: Yep. So a lot more potential for energy. You’d have an energy from the ketogenic diet, but with limitations depending on the duration and intensity. So let’s go back to that topic. As far as an endurance athlete being on a ketogenic diet, where do you see it being the most beneficial? Like, what type of events? I mean, I know we, kinda, touched on it before, but let’s just discuss this real quick, who it might be best for as an endurance athlete and who it may not be best for?
Jordan: Absolutely best for the ultra-endurance athlete, the longer-than-marathon distance, especially when you’re talking about these very long events that are six plus hours long, would definitely reap the most benefit. And I think for, like, track athletes, I don’t think there’s really a whole lot of benefit because they’re purely anaerobic almost all the time.
Matt: Makes perfect sense. So that, kinda, leads me to my next question. What was my next question? So that, kinda, leads me to my next question. And it’s, kind of, a tricky one. Do you think a ketogenic diet is superior to a high-carbohydrate diet for endurance athletes? And let me just say this. There’s thousands of studies on high carbohydrates in endurance athletes. And I would say, like, research studies that examine the ketogenic diet in endurance athletes are pretty sparse compared to the latter or the former, excuse me.
Jordan: Yeah. So I think one of the problems with the current state of the research on ketogenic diets is that we haven’t examined it in the right context. So we’ve always taken the therapeutic type of approach and then applied it to athletics. And that doesn’t work. So I think that being in ketosis as a healthy individual is a little bit overrated. And I say that as somebody who’s been consuming a ketogenic-ish diet for the better part of the last five years. I say that as an athlete, obviously, not an endurance athlete, but, like, I’ve gone up to…I’ve gone over 200 grams a day.
And I regularly eat over 100 grams a day carbohydrates. And I’m able to maintain ketosis at least most of the time. And I’ve actually adapted. How I define my own diet, I say I’m on a low carbohydrate diet that is sometimes ketogenic. So I think for, in terms of which one is better for the general endurance athlete, I think if you’re competitive, again, it’s a tool. It’s something that we can use to modify our metabolism a little bit just to increase our metabolic flexibility. So even if it’s something you’re not comfortable with doing all the time, it’s something that can be used when you’re not competitive to increase your ability to oxidize fats, okay?
Now, when we’re talking about, if you were to want to use it during the season, I think that eating carbohydrate is an important part of that. And I don’t think that you should be concerned with being in ketosis all the time. So if you have a high-intensity event or a high-intensity training session, I think you should eat carbohydrates because what you want from that session is performance. What you want in your race is performance. You don’t want to be bogged down at all, but again, this is, kind of, just a more extreme model of that carbohydrate periodization. So instead of being high carb all the time and just kind of, like, temporally changing when and what types of carbohydrate you eat, it’s just, like, a more extreme variation of that where you’re more often low carb than you are high carb. And sometimes you drift into ketosis.
Matt: Got you. So I think the main point here is, like, most people think, like, ketogenic diet, you have, like, little to no carbs, but Jordan’s basically saying that it’s okay to have some carbs on the ketogenic diet as it relates, I mean, to performance. Like I said before, the ketogenic diet by itself, high-intensity efforts. If you’re not eating carbs, your performance may suffer, but if you introduce a little, you know… I mean, how much would you say, like, on a daily basis would be appropriate? I know it’s gonna differ from individual to individual.
Jordan: Definitely, activity dependent. So our great friend, Eric Serrano, says, “Carbohydrates are activity dependent.” And that’s very much true from a metabolic perspective. Carbohydrates supply energy, and they don’t do a whole lot else in the body. So if you are at a higher volume, like I said, I am a power lifter so my reliance on carbohydrates is actually very limited because even when I’m weight training, I’m not getting into anaerobic ranges most of the time. I’m usually using an ATP system. So I just have ATP available. I use it. I don’t really need to generate it from carbohydrate that often.
So as an endurance athlete, obviously, you have a little bit of smaller body type, but I think even going up to 100 plus grams a day, even on my off days, I have 80 grams of net carbs. And that’s another point that we can talk about. I think you’d be pretty comfortably able to maintain some degree of ketosis and fat adaptation. On the topic of net carbohydrates, that’s subtracting fiber, subtracting sugar, alcohol because we’re only considering the carbohydrates that are actually going to directly contribute to our ATP generation.

When Should You Eat Carbs On A Ketogenic Diet?

Matt: Makes sense. Now, athletes on a ketogenic diet, should they consume the majority of their carbs right before their endurance workout do you think on a daily basis?
Jordan: It’s best used before and during, possibly after, depending on if you’re gonna have another training session or you have very long sessions on back-to-back days, but before or during or both would be the best time. And I should have mentioned this in the last segment. If you are trying to adapt onto a ketogenic diet, if you’ve never done it before, you absolutely need to go through four weeks of ketogenic dieting before you start to try trading carbohydrates. What happens when you are not in ketosis and you haven’t been in ketosis probably for your entire life, unless you went through a period where you weren’t eating, when you try to adapt, you need to go full in. You can’t just, kind of, like, pussyfoot around and .
Matt: Pussyfoot.
Jordan: You’re not gonna get into it. You’re just gonna end up being in limbo, and you’re gonna be miserable. You’re gonna be somewhere between not adapting and, “Give me some carbohydrates now before I cut your head off.”
Matt: That’s very true. And from personal experience, which I’ll get into in a second, like, when I tried ketosis for the first time, I felt like complete ass for the first three to four weeks. Zero energy, headache, grumpy, angry. I just wanted to eat all the fucking carbs in the world, but I didn’t do it. I didn’t do it. So let’s address one more point, and then we’ll wrap it up.

Is A Ketogenic Diet Healthy?

A lot of people have asked about the health consequences of being on the ketogenic diet. Like, a lot of people think, like, you know, high fat, you know. And that’s the fricking devil. Like, it’s gonna cause coronary arteries and all these other negative health consequences. So let’s discuss, like, ketogenic diet and effects on health.
Jordan: Yeah. So the ketogenic diet’s not gonna kill you. And we actually, as humans, we’re very adaptable. So even just beyond that fact, fat’s an essential nutrient. Carbohydrates are not. And I like to make that point. I also like to say that fruits are vegetables with added sugar. People don’t like that, but no, you’ll see your insulin will go down. Your blood glucose goes down. You have much less risk of diabetes on a ketogenic diet. Your blood lipids is, kinda… sometimes, they get weird. So for the first six months, you might see increases, but they tend to normalize after that.
You might see increases in the LDL fraction of your cholesterol, but you’ll see big decreases in your triglycerides. That’s typical. And as far as, like, other health markers, people report, like, better mental clarity. There are some studies in rats that show greater longevity, none of those in humans yet. But overall, no negative health consequences. And just another point, people who have kind of shifted over to the ketogenic lifestyle, so you’re obviously very familiar with the carbohydrate-based individuals, and I’m very familiar with the ketogenic-based individuals, they think fat’s evil. And we think on this side that carbs are evil. And really, they’re not evil at all. They’re just tools to get us to a certain point.
Matt: And we all know there is one thing that’s evil, and that’s sugar, but we’ll talk about that later, just kidding. All right, so we’re gonna wrap this up. I’m gonna tell you my personal experience on the ketogenic diet right now. Jordan convinced me to do it. I don’t know, about two years ago. And he fully proclaims that I didn’t do it right, but I know I did it right. And I’m gonna tell you one thing, like, I’m, kinda, up in the air about the ketogenic diet quite honestly.
Like, when I was on it, you know, the long slow stuff I felt absolutely amazing, but when I got into, like, my higher intensity part, I’m training this season, you know, I fell flat on my face. And that may be my mistake too honestly as far as not carb loading on the frontend before doing my harder workouts, but for the time being, I’m a little bit of both. I, kinda, do what Jordan does. I, kinda, have a little bit more of a metabolic flexibility. Some days I’ll have higher fat, lower carbohydrates, and I’ll periodize it, and that seems to work pretty well. Jordan, anything else you want to add?
Jordan: Well, just on that note, even the recommendations are starting to soften. And we see people, nutritionist- dieticians going above that 35% in calories from fat limit.
Matt: Very nice. Well, there you have it, Family of Fast. That is everything you need to know about the ketogenic diet as an endurance athlete. If you have a buddy that’s currently on a keto diet or is thinking about it, please share this video with them. If you want other videos like this on endurance training, nutrition, and supplementation, subscribe to the EndurElite YouTube channel or head on over to the EndurElite blog at www.EndurElite.com. Get social with us on Instagram and the Facebook training and nutrition club page. And until next time…
Together: Stay fueled, stay focused, stay fast.
Matt: And stay informed.

What does a Ketogenic Athlete eat? How to become an efficient fat burner. Keto exercise workout tips for endurance or high Intensity. PLUS the insulin index.

This is an expert guest article from Raphael Sirtoli who has an MSc in Molecular Biology and is currently pursuing a PhD in Health Sciences. His day job, however, is neuroscience research at the Behavioral n’ Molecular Lab. Raphael Sirtoli is also the co-founder of Nutrita, a website and mobile app helping people grasp cutting-edge nutrition science, follow well-formulated low-carb diets, as well as reach their health and performance goals. He loves open scientific debate, Crossfit, football, hiking, psychedelic medicine, cold water immersion and cooking for loved ones.

The Ketogenic Athlete – how to be an efficient fat burner, what to eat, how to recover, how to recover.

In this article you will find:

  • How to fuel workouts?
  • What does exercise do to ketone levels?
  • What are the benefits of a ketogenic athlete?
  • Can you build muscle as a ketogenic athlete?
  • The downsides of being a ketogenic athlete!
  • Is keto exercise safe?
  • Exercise and intermittent fasting
  • Electrolyte needs

How To Be A Ketogenic Athlete – how to fuel workouts

The ketogenic diet has become really popular these past 5 years.

More and more people are giving the ketogenic diet a try. It’s vital for those who stick with it to make sure it fits with other important aspects of their life – like working out.

People who start any new diet may already work out or are likely to start. So it really does matter whether you can still work out well when living the keto lifestyle. Thankfully, enough science has surfaced to suggest you’ll be just fine. This doesn’t mean the ketogenic diet is optimal for everyone or should be everyone’s first choice, but it’s certainly a fabulous option to try out.

Ketogenic Athlete – Relying more on fat, less on glucose.

The main difference between exercising whilst in nutritional ketosis versus out of ketosis is how much you’ll be able to rely on fat versus glucose to fuel the effort. The more fat adapted you are, the more you’ll rely on fat for fuel. This is true for all exercise intensities, even during high-intensity efforts where glucose use predominates.

Interestingly, what explains the performance difference between well-trained runners and recreational ones is not their ability to use glucose but their ability to burn fat – the more the better .

What does exercise do to ketone levels?

LOWER INTENSITY endurance activity INCREASES ketone levels

If you’re on a ketogenic diet and you start exercising at a low to moderate intensity, your blood ketone levels will increase and your blood glucose levels will decrease.

This is because you’re demanding even more fat from your fat stores to fuel your activity, some of this fat gets turned into ketones.

That happens when you rely on large enough amounts of fat. Indeed, elite endurance runners eating a ketogenic diet burned 2.3 times more fat than their high-carb counterparts during the peak fat burning stage .

HIGH-INTENSITY activity momentarily DECREASES ketone levels

Say you ramp up the intensity to around 75% or more, what then? Your ketone levels will drop and your blood sugar will increase. This is normal and temporary.

You’re demanding more energy from your body at a faster rate, and since glucose ‘burns faster’ than fat, you start using a higher proportion of fuel from glucose. Although you rely proportionally less on fat at high intensities, you’re still be burning more fat overall because your total energy needs went up.

What are the benefits of keto diets for athletes?

There are several benefits to consuming a ketogenic diet for athletes. Here are four important ones:

1: Ketogenic Athletes – Stable Energy Delivery

Keto diets allow people to rely more on fat for fuel rather than fast-acting glucose, especially during lower to moderate intensity efforts. Since fat is our most abundant and efficient fuel source, this allows keto athletes to exercise longer and with stable energy levels.

2: Ketogenic Athletes – Glycogen Sparing

A further benefit of increased fat burning is the ability to spare glycogen. By sparing glycogen – the storage form of glucose found in muscles and the liver – more of it is available for high-intensity efforts where it’s truly needed.

3: Ketogenic Athletes – Improved Recovery From Lower Chronic Inflammation

Well-formulated ketogenic diet greatly reduced chronic inflammation, a major factor impeding proper recovery after an exercise bout. These ketogenic diets can thus promote better recovery due to their anti-inflammatory properties .

An easy way to do this is to select foods that are both nutrient dense, have a low insulin index, and that you enjoy. Don’t worry, there are many!

4: Ketogenic Athlete – Normalizes Appetite

Additionally, ketogenic diets are renowned for their ability to normalize appetite (i.e. lessen cravings) .

Why is this important for athletes? A properly functioning appetite will allow athletes to eat the right amount of food, at the right time, and more importantly not be tempted by junk-food which will hinder their efforts.

Working out may increase hunger, which can potentially lead athletes who already eat poorly to eat even more junk! (when on a high carb diet).

Can you build muscle on keto diets?

Yes ! And more specifically, ketogenic diets can improve body composition which usually happens by losing body fat without losing (and maybe even gaining) some muscle mass .

Building muscle requires many things, all of which you can get on a well-formulated ketogenic diet. The simple version is as follows.

Workout

You need to put your muscles under progressively higher loads, daily or at least three to five times a week; follow a progressive resistance training program.

Free-weights are great. Alternatively, try gymnastics, resistance bands, and online programmes or apps you can follow on your phone. One great example is Christopher Sommer’s online Gymnastic Bodies Program .

Eat right

Eat enough, especially lots of high-quality (animal) foods. Why is that?

Packing on muscle is costly and requires giving your body the right conditions for doing so (anabolic signals). So if you’re not eating enough for whatever reason, your body won’t spend its limited resources towards building a lean muscular physique (a luxury). More vital processes will be prioritized instead.

Your muscles need the right mix of ‘building blocks’. It comes down to eating a complete range of amino acids in the proper ratios and amounts. It’s actually pretty simple if you just eat lots of animal-sourced foods like fish, meat, eggs, shellfish and dairy.

Plant foods alone are not adequate for building muscle. They either entirely lack or have insufficient amounts of essential amino acids, such as methionine or tryptophan, to sustain healthy physiology and especially muscle hypertrophy.

A generous intake of animal fat is also important. These fats are precursors for steroid hormones used to build new cells. They also help you absorb many micronutrients crucial for building muscle. They also help you avoid chronic inflammation that causes muscle wasting . It’s crucial to avoid inflammatory high-omega 6 seed oils like the plague !

Sleep well

Sleep is where the bulk of recovery happens yet it’s often the first thing people cut down on when prioritising one’s busy life schedule.

It’s no surprise professional basketballers are known for sleeping 10 to 12 hours after a game or hard training session .

The science of sleep is still quite mysterious, but there are things we know to do (or not do).

  1. Aim for a good 8 hours starting before midnight
  2. Keep a consistent sleep schedule
  3. Avoiding things that disrupt sleep quality (and maybe duration), like alcohol or late-night meals
  4. Avoid blaring screens (blue-light) once the sunset and get sunlight ASAP after waking

Proper sleep is a major regulator of circadian rhythms, our bodies internal clocks orchestrating all of our life-giving and muscle-building functions carried out by our cells .

Not sleeping enough or sleeping poorly signals to your body that something isn’t quite right. This wouldn’t be the right time to divert resources towards costly processes like muscle building.

What are the downsides of keto diets for athletes?

Getting through the first few weeks of a ketogenic diet can be difficult, as nearly everyone will experience withdrawal symptoms from cutting out sugar and flour products. Your body also has to learn to fuel itself with more fat at the expense of carbs. This initial ‘adaptation phase’ is known as the keto-flu.

Be patient, it might take a while to get performance back to baseline

The basic physiological adaptation is actually relatively quick, taking only a couple days . However, getting one’s athletic performance back to baseline or superseding it can take longer.

Studies are lacking to tell us how long, but anecdotal a few weeks to multiple months. This is a significant downside for athletes who have professional obligations and are constrained by their season.

This is why they would do well to make this significant dietary change in the off-season.

The ketogenic diet was assumed to be inadequate for endurance sports under the old carb-loading paradigm of the 1980s. This turns out to be incorrect.

A big reason why is the studies were poorly designed, not granting athletes sufficient time to keto-adapt. There are now better-designed studies suggesting ketogenic diets are not only adequate but might even be superior to classical high-carbohydrate diets for endurance sports .

We don’t yet know if keto is as good (or better) for high-intensity activity

As for high-intensity sports, like soccer or Crossfit, the ketogenic diet was and still is assumed to be inadequate by most researchers.

However, emerging evidence again suggests that ketogenic diets may also be adequate for high-intensity sports ! In truth, however, it remains an open question. People should thus keep an open mind and test the diet on themselves.

Make sure you don’t undereat when exercising on keto

The ketogenic diet is very satiating. This is not a problem per se, but some people may not be eating enough to sustain their performance. They may thus mistakenly blame the diet when in fact the problem is that they’re not eating enough.

Adding in a handful of berries, or high-fat dairy can help them eat a little more without being kicked out of ketosis. Alternatively, this may not be necessary as simply waiting for a little will normalize the appetite.

Keto may increase LDL cholesterol in some people

Lastly, people who are already quite lean and athletic can see their blood LDL-c cholesterol concentration rise on the ketogenic diet despite most or all other markers generally improving . These people have been termed Lean Mass Hyper Responders (LMHR), coined by engineer Dave Feldman of CholesterolCode who first popularized the observation.

An increase in LDL-c cholesterol is not bad per se – although many doctors will worry about it – but the significance of this rise is currently unknown. The worry is understandable given the old dogma that cholesterol is bad and it causes heart disease, despite this hypothesis being thoroughly refuted .

Is it safe to exercise when on a keto diet?

It is safe to exercise/workout on a ketogenic diet. The state of nutritional ketosis is a natural metabolic state your body has evolved to function in. Humans are particularly ‘good’ at ketogenesis (the production of ketones) compared to all other animals.

Make sure your doctors adjust medications dosages on keto

However, just because the diet is inherently safe doesn’t mean that it prevents all potential issues. For example, the ketogenic diet powerfully lowers the blood sugars and blood pressure in people with elevated blood sugars or blood pressure . And working out naturally causes (temporary) swings in blood sugar and blood pressure.

Consequently, people new to the ketogenic diet, and especially those who are working out, should consult their doctor for the following reason:

Many people are on medications for lowering blood sugar or blood pressure and they should make sure their doctor is aware of their new lifestyle changes so that medication doses can be adjusted accordingly

This would also apply to someone not on a ketogenic diet but who is doing intermittent fasting. This is because intermittent fasting also powerfully lowers insulin, blood glucose and blood pressure.

Can you workout while intermittent fasting?

Absolutely !

Intermittent fasting is really just a fancy new term for something humans have naturally done for literally hundreds of thousands of years. The “Breakfast-Lunch-Dinner + snacks” paradigm is a modern invention with no scientific basis. It arose out of a nutrient-poor agricultural diet of grains and sugar, as well as the marketing of cereals and sports bars by manufacturers.

Intermittent fasting is great to maximize benefits from exercise

Humans evolved a different strategy than ruminants (e.g. cows or sheep) who graze continuously throughout the day to obtain sufficient nutrition from their low-calorie, nutrient poor food.

Humans are apex predators who successfully hunted high-calorie nutrient dense prey (e.g. woolly mammoths). Humans only need to eat about twice a day, on average.

This is hard on a nutrient-poor diet but quite natural on a well-formulated one that eliminates sugar, flour and seed oils.

Intermittent fasting isn’t appropriate for most world-class competitors

An elite athlete such as a Tour de France cyclist will need to eat more than twice a day to sustain their incredibly high work output. The vast majority amateur athletes like you and me will do fine on an average of 2 meals a day.

More importantly, it will help you maintain metabolic flexibility; your body’s ability to fuel with fat and glucose to grant you endurance and explosive power. Just to clarify, this doesn’t happen by eating a keto diet some days and then a high-carb diet on others.

It happens by:

  • not eating too often during the day (no snacking)
  • eating nutrient-dense foods that don’t require you to secrete too much insulin
  • doing high-intensity workouts every so often (a handful of times a week or month)

Keto compliant pre-workout supplements

Caffeine and creatine are probably the safest, most tested, efficacious and widely available pre-workout supplements . They can be taken together, although it’s unclear if it’s better to take them together or to take creatine on training days and then caffeine alone on ‘game day’ .

Homemade electrolyte supplementation

Interestingly, creatine can also be combined with electrolytes to achieve a performance benefit . An electrolyte supplement can be a home-made with

  • A few grams of plain old table salt (NaCl)
  • Between 100 and 300 milligrams of magnesium (Mg)
  • Between 50 and 150 milligrams of potassium (K)

Pre-made electrolyte supplementation

However, for convenience, you may prefer to buy a ready-made product like LMNT recharge, a pre-workout supplement concocted by Robb Wolf and Luis Villasenor. I recommend it because it’s simple, safe and effective. This product is specifically targeted for low-carbers and especially people on ketogenic diets.

Electrolyte supplementation is particularly important when starting a ketogenic diet and working out.

How To Be A Ketogenic Athlete – conclusion

In summary, a well-formulated ketogenic is totally compatible with athletic efforts.

For elite athletes, a keto diet is also an option, but there are more uncertainties; is the ketogenic diet optimal? What kind of athletic efforts are most likely to lend themselves to a ketogenic metabolism?

Most people have some degree of chronic inflammation and fat to lose, both of which make the ketogenic diet a great option.

Make sure you supplement with electrolytes when starting the diet if you feel the keto-flu coming on (especially if working out). And most importantly, exclude flour products, sugar and seed oils to make your ketogenic diet healthy.

Here’s Why the Keto Diet May Hurt Your Athletic Performance

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Ketogenic diets are not just for losing weight. Many endurance athletes also turn to these very low-carb, high-fat diets to boost their performance.

But athletes involved in high-intensity, short-duration sports might see drops in performance while on a ketogenic diet, suggests new research.

Researchers from Saint Louis University tested the anaerobic exercise performance of 16 men and women following either a low-carbohydrate ketogenic diet or a high-carbohydrate diet for four days.

People on the ketogenic diet performed more poorly at anaerobic exercise tasks than those eating more carbs.

Depending on the task, their performance was 4 to 15 percent lower than the high-carbohydrate group.

The study was published last month in the Journal of Sports Medicine and Physical Fitness.

Study author Edward Weiss, PhD, associate professor of nutrition and dietetics at Saint Louis University, said that the results could make a big difference to athletes involved in sports that depend on short-burst anaerobic activities.

This includes sprint-type activities that occur in soccer and basketball and also short, intense activities like the 100-meter sprint and the triple jump.

Weiss added that the study “probably also applies to many aerobic activities, as other studies have demonstrated that high-intensity aerobic exercise performance may be compromised by low-carb diets — including keto.”

In light of these results, he advised athletes to avoid these diets unless they have “compelling reasons for following a low-carb diet.”

While this is a small study and people were on the two diets for only a few days, a 2017 review of previous research found similar early onset fatigue during short-duration activities while on a ketogenic diet.

Weiss said that additional studies will provide more insight into the pros and cons of ketogenic diets for athletic performance. For now, he suggests that athletes “err on the cautious side.”

Carbs or low carbs for energy

Endurance athletes such as marathon runners and long-distance cyclists might fare better on a ketogenic diet than players who use short bursts of energy.

Dr. Clifton Page, an assistant professor of orthopaedics and family medicine at the University of Miami Miller School of Medicine, said “ketogenic diets appear to be beneficial for endurance athletes after a period of adaptation.”

Page said it can take several months on a ketogenic diet for the body to switch from using carbohydrates as its main energy source to using fats — the “adaptation period.”

To support the body as it makes the switch, ketogenic diets are very high in fats.

Zach Bitter, an ultra-marathoner and holder of the 100-mile American record and 12-hour world record, said “fat is always the primary macronutrient in my diet. It can reach as high as 70 percent when I am recovering from a big race or workout.”

But this doesn’t mean ketogenic diets are high-protein diets.

In fact, eating too much protein can interfere with the production of ketones. These ketones are byproducts from the breakdown of fats and can be used as an alternative fuel source for the body when there isn’t much glucose.

Also, continuing to carb-load — such as with energy drinks and gels — can inhibit the body’s switch to using ketones for energy.

“Metabolically, a high-carbohydrate diet locks an athlete into a dependence on glucose as the dominant fuel for exercise,” said Jeff Volek, PhD, professor of human sciences and a registered dietitian at The Ohio State University and a leading researcher of carb-restricted diets.

The body stores some glucose for later as glycogen. But Volek said the body has only enough glycogen to last about one day, or for just a few hours of hard exercise.

So athletes on a high-carb diet need a steady intake of carbohydrates “to prevent this small carb fuel tank from running dry,” he said.

Bitter said that since he switched to a ketogenic diet, he has been able to cut his in-race fueling by over 50 percent.

He is quick to point out, though, that he doesn’t “demonize carbs.” But he tends to favor “low-glycemic sources of carbs in my meals when I do have them during peak training.”

One diet fits all athletes?

For endurance athletes, long-term use of ketogenic diets may boost not only performance, but also overall health.

“Keto-adaptation has enabled endurance athletes to set course and national records,” said Volek. “And a growing number of military personnel are using ketosis to improve physical and cognitive performance and manage obesity, metabolic health, oxygen toxicity symptoms, and post-traumatic stress disorder.”

Research — including a recent study by Volek — found that ketogenic diets may reduce body fat, type 2 diabetes, and metabolic syndrome. The last one is a group of conditions that includes high blood sugar and abnormal cholesterol levels.

“More than half of adults have prediabetes or diabetes in the U.S., including athletes,” said Volek. “A well-formulated ketogenic diet reverses the insulin-resistance phenotype more potently than any drug or lifestyle therapy.”

Bitter said he was attracted to a ketogenic diet not for the performance boost, but because during his training he would “wake up multiple times a night, experience big energy shifts throughout the day, and would get noticeable swelling in my legs and ankles after big workouts and races.”

The ketogenic diet helped with these symptoms.

Not everyone thinks ketogenic diets are for every athlete.

“In many cases, you can still perform well at your chosen sport on very few carbs. But you are unlikely to perform at as high a level as you’re accustomed to, and you’re certainly not likely to perform your best,” said Mike Israetel, PhD, head science consultant at Renaissance Periodization.

He added that your recovery after exercise will also be “significantly hampered, which will of course interfere with both performance and rates of improvement from training.”

Page warned that research shows that “without long-term adaption to the ketogenic diet, an athlete could experience adverse effects including reduced muscle glycogen, hypoglycemia, and impaired athletic performance.”

If you do opt for a ketogenic diet, it’s important to follow a plan designed by a nutritionist — or even work directly with someone experienced with these diets.

While a lot of research focuses on the benefits of ketogenic diets for competitive athletes, weekend warriors and others may also benefit.

“Recreational athletes tend to see more consistent benefits from adopting a ketogenic diet,” said Volek. “In part because, on average, they have a greater emphasis on weight loss, metabolic and health benefits.”

Keto Diet Meals And Supplement Guide For Athletes

Keto Diet Meals | Ketosis Breakfast Menu | Keto Athlete Meal Plan | Basic Keto Meals

No matter, what the field is when you proceed without a solid plan you tend to end up in failure. Same goes with the keto diet. This complete keto diet meals and supplement guide has been crafted by researchers and athletes who have successfully switched to the keto diet.

Some athletes adapted this diet for years and achieved leaner body, excellent performance, whereas, many quit within a few months. The only reason of failure has been the lack of personalized rock-solid keto diet meals plan.

Calculate Your Required Macro-nutrients Before Planning Your Keto Diet Meals

You may find the calculation troublesome and dull, but it’s essential for the first few weeks. Keto diet will be counteracting everything you have done so far, tracking the nutrients will help you point out where you’re lagging behind and get it corrected. Now, you need to rework your protein, carbohydrate and fat intake and plan your keto diet meals accordingly.

Net Carb Intake (carb – fiber) (5% to 10%): Below 50 grams daily. Later on, you can lower it to 30 grams as well.

Protein Intake (15% to 20%): Within 0.6 to 1 grams per pound of lean mass (body weight – fat). Therefore, protein intake range for a 190-pound athlete with 15% body fat will be 96.9 to 161.5 grams daily.

Lean mass= 190 lbs. – (190×15%) =161.5 lbs. lean mass.

Therefore, 161.5 lbs. x 0.6 g. = 96.9 g.

161.5 lbs. x1 g. = 161.5 g.

If you are unaware of your body fat percentage, use a calorie calculator and multiply the result with 0.15 to 0.20 to define your daily protein intake.

Fat Intake (70% to 75%): Just fill up the rest with fat but, not with polyunsaturated fats.

♣ If you want to gain weight add 500 calories or 55 grams of fat.

♣ If you want to lose weight cut down 200 to 500 calories or 22 to 55 grams of fat.

Plan Your Grocery List

Before you go shopping, just get rid of your secret high-carb stashes (like fruits or underground vegetables). For the next few days, you are going to crave (very badly) for them.

♣ Nuts and seeds (cashew, almond, pumpkin).

♣ Whole eggs.

♣ Full-fat cheese, cream cheese.

♣ Beef, bacon, chicken thigh & broth, pork rinds, fatty fish.

♣ Low-carb vegetables.

♣ Avocado, berries.

♣ Olive oil, heavy cream, salted butter, sour cream.

Things You Should Take Care Of

♣ Make sure you have plenty of water and sodium. Have a cup of broth when feeling too weak.

♣ Lack of sodium, potassium, magnesium can cause keto flu and other side effects. Have plenty of salty food, leafy vegetables, avocado and nuts like almond, pecan, walnuts.

♣ Add a bouillon cube in a cup of hot water with a tablespoon of salted butter in case you are having muscle cramps or headaches.

Keto Workout Supplements

There are several performance-boosting supplements that are also keto-friendly including beta-alanine, caffeine, creatine monohydrate. Some branched-chain amino acids (BCAA) can lead to glucose production. However, if it’s improving your performance then drink it during the training, but not throughout the entire day. Also, tossing down a few bouillon before your workout would stabilize your sodium and magnesium levels. If you need a post-workout protein shake, make sure it’s a zero-carb one.

Sample Plan of Keto Diet Meals For The Day

Meal Options
Breakfast Fried eggs, bacon and sautéed spinach.
Sugar-free sausage, roasted bell pepper, pepper jack cheese.
Lunch Taco salad of ground beef, romaine lettuce, cherry tomatoes, cheddar cheese, avocado, sour cream with taco seasoning.
Lettuce wraps including stuffing of bacon, grilled chicken, cherry tomatoes, jack cheese and mayonnaise.
Dinner Pork chops with mushroom sauce, steamed asparagus.
Baked salmon with mashed cauliflower, bacon and cheddar cheese.

You need to calculate your macros and figure out the portions of the ingredients of your keto diet meals. With these tips, you can surely make any number of high-fat keto diet snacks. But remember, to check your ketone levels regularly. You need facts and data to ensure your plan is working! Lastly, enjoy your keto diet meals!

Keto Diet Meals | Ketosis Breakfast Menu | Keto Athlete Meal Plan | Basic Keto Meals

Keto for endurance athletes

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