If you think that carbohydrates are needed for exercise, it’s time to think again. A low-carb diet is perfectly compatible with exercise and combining the two can bring significant benefits.

In fact, a number of athletes have cited keeping carbohydrate intake low as being beneficial towards their training and performance.

In this article, we will look at some of the research into low-carb diets and exercise as well as the precautions to be aware of if you’re on medications that can lead to low blood sugar levels.

Carbohydrate is not needed for exercise

It used to be widely thought that carbohydrate was needed for exercise. However, research has provided clear proof that low-carb and very-low-carb diets are no barrier to exercising.

One of many examples is a 2015 research study which essentially pitted two teams of experienced endurance runners against each other. 10 of them ate a diet in which carbohydrate accounted for 60% of their calories. The other team of 10 ate a very-low-carb diet in which only 10% of calories came from carbohydrate.

The runners were instructed to run for 3 hours and their ability to burn fat was monitored. The results showed that, not only were the runners on a very-low-carb diet perfectly able to run for three hours straight, they also burned more body fat than the high-carb team.

How the body adapts to low-carb and exercise

The human body can cope with exercising without carbohydrate in a number of ways.

Firstly, there’s the sugar we store in our muscles as glycogen It doesn’t matter whether you are on a low-carb or a high-carb diet, either way, your body will maintain a plentiful supply of stored sugar (glycogen) which will be available for use when exercising.

Secondly, as we’ve seen above, the body can also burn body fat for energy whilst exercising.

Famous athletes that have used low carb diets

The advantages of low-carb diets have not gone unnoticed by professional athletes at the top of their sports.

A striking example is Chris Froome who overhauled his diet to reduce his carbohydrate intake and replace it with more fat and protein. The change in diet enabled Chris to maintain a low but muscular body weight and helped him to win three Tour de France titles.


It’s important to note that if you are on medications that can cause hypos (such as insulin, sulphonylureas and glinides) then it is important that you take precautions to prevent hypos occurring.

This may include reducing your dose of these medications prior to prolonged or intensive exercise.

If you are on any of these medications and are not used to exercising on a low-carb diet, it is important to discuss which precautions to take with your doctor.

The general consensus around the Paleo world is that the more active you are, the more carbs you need. That’s especially true if the exercise is intense: walking is one thing, but if you’re getting up into the high-intensity sprinting or ten-mile runs, your body will be hurting for some carbs.

This is all based on science, but the vast majority of the science is from a very limited population: trained elite athletes, and/or college-age men doing intense exercise and not looking to lose weight. What about the people who aren’t doing sprinting or 10-mile runs, but might be doing occasional squatting or 3-mile runs? What about middle-aged men? What about women? What about people who went low-carb to lose weight?

There’s plenty of anecdotal evidence about exercise on a low-carb diet, but it’s all conflicting. On the one hand, beginners often start trying to do a hard workout every day on a low-carb version of Paleo where they’re also trying to restrict calories for weight loss. Then they get exhausted and their performance completely tanks, but if they add in a potato or two every day, they perk right back up again and feel fine.

But on the other hand, there are also plenty of anecdotes about people who eat low-carb and feel just fine in the gym. So here’s a look at some studies on low-carb diets for ordinary non-athletes, how they affect exercise, and the role of different individual factors (for example, everything can change depending on whether or not weight loss is involved, which is not something you’ll find in the elite athlete studies).

Performance on a Low-Carb or Ketogenic Diet

When it comes to diets and athletic performance, it’s important to distinguish between a true ketogenic diet and a low-carb diet that isn’t ketogenic. If you don’t know about the science behind ketogenic diets, here it all is – the rest of this section will wait.

Low-Carb Diets: Just Not Enough Evidence

The problem with low-carb-but-not-keto diets is that there isn’t a huge amount of evidence on anything that counts as actually low-carb to the Paleo crowd (50% carbs is…not low-carb). This review cites the studies we have, and concludes that there just isn’t enough evidence to give one statement on the effects of low-carb diets on performance once you give the athletes enough time to adapt to them. Quite a few showed a performance decrease. One study showed an advantage for low-intensity exercise, but a few others showed no advantage, and none showed any advantage for high-intensity.

Ketogenic Diets

The great champions of ketogenic diets for athletes are two researchers called Jeff Volek and Stephen Phinney. Here’s a free full-text from the latter that covers a lot of interesting stuff about the history of ketogenic diets for athletes. He goes over the Inuit diet, and two examples of people who did hard labor on a ketogenic diet in the arctic (the Schwatka expedition of 1878-80 and anthropologist Vilhjamur Stefansson in 1906-7). Then he discusses the history of studies finding performance improvements and impairments in athletes on a ketogenic diet. A few conclusions from the review:

  • It takes a few weeks to fully adapt to the diet, even in well-trained athletes.
  • Electrolytes are crucial, especially sodium and potassium: the Inuit ate a high-salt diet, and athletes fed a high-salt keto diet did better than athletes on a lower-salt diet.
  • Protein is also important. Phinney recommended about 15% of the diet as protein (that’s low by Paleo standards, but that’s how keto works).

Even in studies where everything was “right,” the review concluded that exercise during ketosis was safe, “with the one caveat that anaerobic (ie, weight lifting or sprint) performance is limited by the low muscle glycogen levels induced by a ketogenic diet.”

Performance Limitations, but it’s Not That Bad

So far, these studies suggest that low-carb or ketogenic diets do limit performance in intense exercise, but that it’s still safe and feasible to exercise while you’re on them provided you know how to work with your body’s new limitations and not overtrain or push it too hard. If you’re not one of the elite athletes in most of the studies, you might not care much about the performance decrease, or the other benefits of low-carbing could be worth it. Just to take one example, if you could easily cure years of painful and embarrassing acne at the cost of adding :30 to your mile time – worth it, right?

What Happens when you Add Weight Loss?

One reason why all that research might not be immediately applicable is that the study diets usually weren’t trying to cause weight loss (or were actually designed to avoid it). But most people interested in low-carb Paleo + exercise are interested in it primarily for weight loss.

A weight-loss version of a low-carb diet could affect athletic performance differently than the study diets above.

  • Eating below maintenance calories (whether it’s the automatic keto “just not hungry” style of restriction or deliberate counting-style restriction), hurts athletic performance.
  • On the other hand, losing weight (whatever diet you used) tends to make people faster and make exercise easier.

Here’s an interesting pair of studies on very gentle exercise while eating a low-carb diet for weight loss. The first one is from 2009. 60 overweight and obese adults ate either a low-carb or a low-fat diet for 8 weeks. The subjects were also encouraged to exercise. At the end of the 8 weeks, they did tests of strength and aerobic endurance.

  • Weight loss was slightly larger in the low-carb group.
  • Both groups lost muscle mass and handgrip strength (which is what you’d expect – they were dieting, and some muscle loss is inevitable on a diet).
  • Both groups got better at treadmill walking, with the improvement directly proportional to the amount of weight loss.

There were no significant differences in exercise performance between the groups. The high-carb group did just as well as the low-carb group.

This study from the same researchers ran for a whole year. It also looked at overweight and obese adults, and compared a low-carb and a high-carb diet. The results were effectively the same, with one exception: the low-carb group didn’t lose any more weight than the low-fat group. But just like the previous study, this one found a loss of muscle mass and strength, but an increase in ability to walk on a treadmill.

So what does all this mean? There’s a tangle of effects from exercise, diet, and weight loss here, but practically, if you’re overweight or obese, and if you’re going to do gentle exercise while you diet, a low-carb diet probably isn’t any worse than a low-fat or low-calorie or any other kind of diet.

But this study found that a ketogenic diet made people tired more quickly and reduced their desire to exercise (this was in untrained, overweight adults). Considering that the “high-carb” group in the study above (about 45% carbs) got the same weight loss as the low-carbers (around 5% carbs), it might be worth upping the carbs a little if workouts suddenly start feeling exhausting.

Summing it Up

Here’s what we know so far:

  • For low-carb diets that aren’t for weight loss: studies on elite athletes have shown that in general, low-carb cause a moderate impairment, especially in anaerobic activity like sprinting and lifting weights. For normal people who aren’t interested in breaking any world records, that might not be a huge issue.
  • For weight loss: a few studies on obese people doing very moderate exercise showed no advantage of high-carb over low-carb diets.

What about the people doing low-carb dieting for weight loss but doing a whole lot more than treadmill walking? This is the population most prone to overtraining and burnout. What we really need are more studies, but remember:

  • Dieting is a stressor.
  • Carb restriction can be an extra stressor. It’s not a magic band-aid for overtraining.
  • Carbs are one aspect of recovering from intense workouts. Without them, you may recover more slowly or see a drop in performance. If you don’t want to plan for that, the solution is to eat some carbs, not to “push through” with caffeine.

Don’t be the people from the beginning, who try to combine extreme carb/calorie restriction with 7-days-a-week CrossFit and end up burning out.

Everyone’s body is a little different when it comes to carbs. Yours will tell you if you’re overdoing it, or if the low-carb + half-marathon training + weightlifting + Tae Kwon Do thing just isn’t working. Listen to it.

Are you following a low carb diet, but not losing weight?

Have you tried a low carb diet and didn’t lose a pound? Or maybe you lost some weight in the beginning, but have reached a plateau?

In this article, I will show you how to blast through that plateau and lose weight again with a low carb diet. I’ll also tell you why measuring your progress by weight loss alone is sometimes confusing and deceptive and maybe even self-defeating.

I’m going to give you a much better way to track progress; one that’s sure to tell the whole story and encourage you every step of the way!

Remember, fat loss is not always the same as weight loss!

Low-carb diets are a strong ally against some of the biggest health problems that plague the world today.

While I like a low carb diet, we all remain unique and it doesn’t always work for everyone.

Most people who give it an honest try do quite well and lose weight without restricting calories or feeling hungry.

However, after a few weeks, some people reach a plateau.

The weight may have fallen off at the beginning, but now the scale won’t budge.

If you reached a plateau or just the results you are harvesting/harvested are not as satisfying as you expected, here are a few suggestions that would explain why:

Are you Eating Real, Whole Foods ?

Eating a low-carbohydrate diet is not just about lowering your intake of carbohydrates. It is about eating real, whole, nutritious foods.

Go through your pantry and kitchen and eliminate all processed foods. This includes protein bars, snack foods, and sugary beverages.

Also read: Sugar Addition

Choose lean meats like chicken or fish, eggs, vegetables and healthy fats such as coconut oil, avocado and nuts.

While a certain food such as cookies and brownies may be made with healthy ingredients, they should NOT be eaten every day.

Cutting back on processed carbohydrates is the way to go, however you want to make sure you are eating good fats that will keep you full and satiated.

I personally recommend Chaga Organic Extract Powder from Lost Empire Herbs and recommend it based on its superior quality and value. It promotes an overwhelming sense of Energy, Vitality, Metabolism, Wellbeing, and Longevity and is crucial for digestive health when on a low-carb keto-type diet. Click on the link to see how their extraction process is superior and get 15% off your first order.

Weight Loss Is A Process

The human body is made up of many different tissues including the fat under the skin as well as the fat inside the abdominal area.

However, our bodies are made up of 60% water and other tissues such as muscle and bone also contribute to a significant portion of our total body weight.

If you’ve recently started exercising, then good chances are that you’re adding some muscle mass to your frame.

If you’re female, then your weight may fluctuate slightly according to your hormonal cycles.

Your weight may also be affected by what you ate yesterday, your hydration status, how long since you visited the toilet.

All those things can cause minor fluctuations in body weight.

Therefore, even if the scale doesn’t budge a few days or even weeks, it doesn’t mean you’re not losing body fat.

Are You Really Stalling?

While the scale is a useful tool to measure weight loss results, it does not tell the whole story.

In fact, constantly weighing yourself can be self-defeating at best. What you’re after ultimately is burning body fat.

You can have your body fat measured by a nutritionist or simply use a measuring tape to measure your waist circumference, arms and thighs.

Take a picture of yourself every two to four weeks without clothes or in a bathing suit. You will be able to really see the progress you are making.
Some people don’t even use a scale. They go by how they feel, how they look and how their clothes fit.

Are You Really Eating Low-Carb ?

Are you eating fresh, whole, natural foods every day? Are you having a ‘cheat’ meal more often than not? Are you really eating low-carb?

Be honest with yourself – ask yourself these questions and answer truthfully.

It is helpful to use an online log to keep track of your food intake. Many websites, such as Fitday, offer carbohydrate and calorie counts, in addition to protein and fat.

Knowing the amount of carbohydrate in a food may surprise you. You may find that you are eating more than 100-150 grams of carbohydrate per day and this could definitely cause you to stop losing weight.

There are some foods that can be problematic. Nuts and high-fat dairy products such as cheese are acceptable to eat, but they still are very high in calories and easy to overeat on.

If you’re eating nuts and/or cheese every day, between meals, in large amounts, then you should probably cut back and see if the weight doesn’t suddenly start moving again.

I’m personally not against potatoes and some healthy non-gluten grains from time to time, but to break through a weight loss plateau you might want to eat nothing but protein, fat and low-carb veggies for a while.

Cheat meals can be problematic. I’m not entirely against the occasional cheat meal if it is moderate and doesn’t make you go 5.000 calories over your expenditure for the day.

Try sticking to whole, natural carbs instead of junk food during your “cheat” meals. If that doesn’t work, skip the cheat meals altogether for a while.
When it comes down to it, weight loss is still a matter of calories. Again, try logging your food intake for a while to see how many carbs and calories you are taking in.

If they greatly exceed your requirements, then maybe you’re just eating too damn much.

Are You Exercising?

Of course, what you eat is very important when it comes to weight loss, however regular exercise is definitely part of any healthy lifestyle.

Weight training exercises combined with cardiovascular workouts work best. Aim for strength training at least 2-3 times per week and make a point of walking or riding a bike every day.

If you’re completely sedentary, then you are (in my opinion) effectively broken. You’re not living life even close to your genetic potential. Get moving!

Is Any Medical Condition Getting in Your Way?

It is no secret that many medications can cause weight gain or make it impossible to lose weight.

If you are taking any medication, read the list of side effects. Weight gain may be on the list, and if so, make an appointment with your doctor.

He or she may suggest an alternative drug or perhaps the dosage can be lowered to avoid the weight gain.

If you are eating healthy and exercising on a regular basis and still not seeing results, there may be an underlying medical problem that should be addressed.

There are many hormonal disorders that can make it impossible to lose weight such as hypothyroidism.

Your doctor can rule out any health issues or concerns that might be hindering your ability to lose weight and get healthy.

I personally recommend Chaga Organic Extract Powder from Lost Empire Herbs and recommend it based on its superior quality and value. It promotes an overwhelming sense of Energy, Vitality, Metabolism, Wellbeing, and Longevity and is crucial for digestive health when on a low-carb keto-type diet. Click on the link to see how their extraction process is superior and get 15% off your first order.

Do You Have A Healthy Lifestyle?

Are you stressed out ? Are you getting enough sleep every night?

Identifying and dealing with stressors in your life through yoga or meditation, for example, is the way to go.

Poor sleep and stress can chronically elevate your cortisol levels, which is bad and can hinder your weight loss.

Turn the computer and television off before bedtime. Read a book, meditate or enjoy a cup of chamomile tea before bed. All of these activities will help calm your mind and body so you can get a good night’s rest.

Be Realistic

Losing fat takes time. A pound per week is a reasonable goal. Two pounds per week is perhaps too ambitious for some people.

We’ve all heard stories of those people who lose a ridiculous amount of weight in a short amount of time.
100 pounds in a year? Wow, impressive, but this is the exception, not the norm.

When you get closer to your goal weight, losing those last pounds becomes multiples times harder. Those last few stubborn ounces of body fat over your abdomen may seem impossible to get rid of.

When you reach this point, I think it is time to take it easy. Continue eating healthy, continue exercising, live your life to the fullest and stop focusing too much on those last few pounds. Hopefully, they will go away with time.

We also have to be realistic. Not everyone can lose all the weight they want. People who have been obese for a long time may not be able to completely reverse it.

Perhaps the best thing to do in that scenario is to just enjoy your improved health and wellbeing and maintain this for life.

You will live longer, feel better and have a peace of mind knowing that you did everything you could.

Handy Hints

I don’t really talk much about intermittent fasting on the keto diet on this blog, but I do know that it is a technique that can improve health and accelerate weight loss.

If this is something you would like to consider, make sure you do not have any medical issues such as Type-2 Diabetes. Then skipping breakfast and lunch and not eating until dinner one day of the week may make a large difference.

High intensity interval training (HIIT) is another technique that can get things moving. Sprints, hill sprints, even rope skipping or cycling, doing these intervals can be very effective.

Also, there are a ton of “low carb diets” and one might suit you significantly better than another. Do some research on the following and see if they might be a better fit. (in alphabetical order)

  • Atkins Diet
  • Eco-Atkins Diet
  • Bulletproof Diet
  • Dukan Diet
  • Keto Diet
  • Scandinavian Low Carb, High-Fat Diet (LCHF)
  • Paleo Diet
  • Slow Carb Diet
  • South Beach Diet
  • Whole30 Diet
  • Zero Carb Diet
  • Zone Diet


When it comes down to it, it is still all about eating healthy, exercising and living a healthy lifestyle.

If you’re not losing weight or have reached a plateau, then these pointers above should keep you busy for a while trying out new things in order to get that damned scale moving again.

Have you ever gone through a weight loss plateau and managed to break through it successfully? Please tell us all how you did it in the comments.

Low carb, paleo, keto…if it seems like everyone but you is off bread lately, it’s probably because they’re on one of these diets. And while the diets themselves aren’t exactly new, it certainly seems like a lot of people are suddenly cutting back to some degree or another on the macronutrient that has long been human beings’ primary source of energy.

While for some of us this idea is, tbh, flummoxing in and of itself (you can pry my bread and bananas from my cold, dead hands, thank you) it’s also confusing to even differentiate between all these popular diets. What is paleo versus keto? How low is low carb?

We’ve got answers.

Before we get into the nitty-gritty of paleo versus keto versus low carb, though, it’s important to put this carb-slashing into the context of what the evidence tells us about diets in general. There is no best diet for everyone (or even most everyone), and while most diets can result in short-term weight loss they also tend to fail in the long term. If weight loss is your goal, you should know that weight is determined by a multitude of factors beyond diet—many of which are out of your control—and it is not the only measure of health. For all of these reasons and more, it’s definitely advisable to first consult a doctor or work with an R.D. if you decide to begin a diet like low carb, paleo, or keto. It’s especially important to check in with a health-care provider before starting any diet if you have a history of disordered eating or any health conditions.

With all that said, if you’re just curious about what each one of these diets entails, we’ve got some helpful information. Here, we lay it all out: Where these diets come from, what they’re based on, how they’re similar to one another, and, most important, what you actually eat on them.

What eating low carb actually means

Low carb is a flexible, generic term that can describe any pattern of eating where you consume a fewer-than-average number of carbohydrates, New York–based dietitian Samantha Cassetty, M.S., R.D., tells SELF.

What’s average? It depends on who you ask. But as a baseline we can work off the 2015–2020 Dietary Guidelines, which sets the Acceptable Macronutrient Distribution Range (AMDR) for each of the macros (carbs, fat, and protein). The AMDR represents the range of intake of a given macro that is associated with a decreased risk of chronic disease and sufficient intake of essential nutrients. Anything outside of the AMDR and you may begin to potentially increase your risk of chronic disease or nutrient insufficiency, per the Dietary Guidelines.

For carbs, that target range is 45 to 65 percent of your total caloric intake. (So someone eating 2,000 calories a day would get 900 to 1,300 of their calories from carbs. Carbs contain 4 calories per gram, so that comes out to 225 to 325 grams.)
Then “when you get less than 45 percent of your energy from carbohydrates, that’s where we generally start to classify diets as low carb,” Jennifer Bruning, M.S., R.D.N., L.D.N., national spokesperson for the Academy of Nutrition & Dietetics (AND), tells SELF.

Beyond that, low carb is not really a prescriptive diet. There’s a lot of leeway in how you reach that under 45 percent mark. “A low-carb diet can drastically reduce carbs and can be very restrictive, or it can be more moderate and inclusive of different foods,” Cassetty explains. Technically a person getting 10 percent of their calories from carbs and a person getting 40 percent of their calories from carbs are both technically eating low carb. There are also no foods expressly included or omitted, meaning you could stick to only low-carb foods or incorporate moderate portions of high-carb foods, like bread or potatoes. (However, it is likely that your diet will naturally include more protein and fat to compensate for the reduction in carbs.) So ultimately the degree to which you curb your carb intake and how you get there is up to you.

Low fat, low carb, or Mediterranean: which diet is right for you?

Losing weight sometimes takes experimentation. If you give a diet your best shot and it doesn’t work long term, maybe it wasn’t the right one for you, your metabolism, or your situation. Genes, family, your environment — even your friends — influence how, why, what, and how much you eat, so don’t get too discouraged or beat yourself up because a diet that “worked for everybody” didn’t pay off for you. Try another, keeping in mind that almost any diet will help you shed pounds — at least for a short time.

Here’s a look at three common diet approaches.

1. Low fat: Doesn’t taste great … and is lessfilling

Once the main strategy for losing weight, low-fat diets are now less popular. Since fat contains nine calories per gram while carbohydrates contain four, you could theoretically eat more without taking in more calories by cutting back on fatty foods and eating more that are full of carbohydrates, especially water-rich fruits and vegetables. But if the carbs you eat in place of fat are highly processed and rapidly digested, you may be sabotaging your weight-loss plan.

2. Low carbohydrate: Quick weight loss but long-term results vary

Eating carbohydrates — especially highly processed ones like white bread and white rice — quickly boosts blood sugar, which triggers an outpouring of insulin from the pancreas. The surge of insulin can rapidly drop blood sugar, causing hunger. Low-carb proponents claim that people who eat a lot of carbohydrates take in extra calories and gain weight. Limiting carbs in favor of protein and fat is supposed to prevent the insulin surge and make you feel full longer.

To make up for the lack of carbohydrates in the diet, the body mobilizes its own carbohydrate stores from liver and muscle tissue. In the process, the body also mobilizes water, meaning that the pounds shed are water weight. The result is rapid weight loss, but after a few months, weight loss tends to slow and reverse, just as happens with other diets.

The American Heart Association cautions people against following the Atkins diet because it is too high in saturated fat and protein, which can be hard on the heart, kidneys, and bones. The lack of carb-rich fruits and vegetables is also worrisome, because eating these foods tends to lower the risk of stroke, dementia, and certain cancers. However, if you do get most of your carbs from vegetables and concentrate on eating primarily healthier fats, this type of diet can work longer term for many people.

3. Mediterranean style: Healthy fats and carbs with a big side of fruits and vegetables

Good fats are the monounsaturated fats found in olive oil and other oils, and the polyunsaturated fats found in fish, canola oil, walnuts, and other foods. (Saturated fat and trans fat are the bad guys.) Mediterranean diets tend to have a moderate amount of fat, but most of it comes from healthy fats. The carbohydrates in Mediterranean-style diets tend to come from unrefined, fiber-rich sources like whole wheat and beans. These diets are also rich in fruits and vegetables, nuts, seeds, and fish, with only modest amounts of meat and cheese.

People living in Mediterranean countries have a lower-than-expected rate of heart disease. But the traditional lifestyle in the region also includes lots of physical activity, regular meal patterns, wine, and good social support. It’s hard to know what relative role these different factors play — but there is growing evidence that, in and of itself, the diet can reduce cardiovascular risk and the development of diabetes.

Make your own

A good diet should provide plenty of choices, relatively few restrictions, and no long grocery lists of sometimes expensive special foods. It should be as good for your heart, bones, brain, and colon as it is for your waistline. And it should be something you can sustain for years. Such a diet won’t give you a quick fix. But they can offer you something better — a lifetime of savory, healthy choices that will be good for all of you, not just parts of you.

For more ideas and information on healthy weight loss, read Lose Weight and Keep It Off, a Special Health Report from Harvard Medical School.

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As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

What raises blood sugar? The simple answer is carbohydrates. So why not just yank them out of your diet like weeds in your garden? Why not quash blood sugar by swearing off bread, pasta, rice, and cereal? Well for one, carbohydrates are the main source of body fuel and include some of the healthiest food you can eat. So it’s a bit more complicated than that.

When low-carb diets first became popular, they seemed to be a breath of fresh air after the low-fat (and high-carb) diets that preceded them. Remember low-fat cookies, low-fat snack cakes, and low-fat everything else? With low-carb diets, suddenly people could load up on bacon and still lose weight as long as they were willing to eat hamburgers without buns and pretty much give up sandwiches and spaghetti. These diets could be effective. Weight loss could happen very quickly, sometimes within days. And it often seemed to come with added health benefits, including lower cholesterol, blood pressure, and triglycerides (blood fats linked to heart attacks.)

One of the most extreme kind of low-carb diet was pioneered by the late Robert Atkins, MD, whose first book, Dr. Atkins’ Diet Revolution, came out in 1972. It promised quick and long-lasting weight loss and prevention of chronic disease, all while allowing high-fat steak and ice cream. Since then, other low-carb diets have allowed small amounts of carbohydrate-rich foods, but they still cut out most grains as well as starchy vegetables and even fruit.

The downsides of these diets

The Atkins diet and the many other low-carb diets that followed in its footsteps have turned out to be less effective than originally claimed. For instance, a 2018 study found that study participants lost the same amount of weight on low fat vs. low carb diets. Also, in the end, many people decided they didn’t want to go through life without ever eating pasta again. Let’s look at what would happen if you followed one of the more extreme low-carb diets.

You may feel terrible

Low-carb diets usually begin with an “induction” phase that eliminates nearly every source of carbohydrate. Often, you’ll consume as few as 20 grams of carbohydrate a day. That’s less than 100 calories’ worth—about what’s in a small dinner roll. On a 1,200-calorie diet, that’s only about 8 percent of your daily calories. By contrast, health experts recommend that we get between 45 and 65 percent of our calories from carbs.

When carbohydrate consumption falls below 100 grams, the body usually responds by burning glycogen (stored glucose) in muscle tissue. When those glycogen stores start to run out, the body resorts to burning body fat. But that’s a very inefficient, complicated way to produce blood sugar. The body tries to do it only when it absolutely has to (such as when it’s starving)—and for good reason.

Turning fat into blood sugar comes at a price in the form of by-products called ketones. They make your breath smell funny and can cause constipation, among other unpleasant side effects, according to the Mayo Clinic. They can also make you tired, lightheaded, headachy, and nauseated. Feeling lousy is certainly one way to dampen the appetite, but not one that most people would choose. “I see a lot of people not drinking enough water or electrolytes in the induction phase which results in the ‘keto flu,’” says L.J. Amaral MS, RD, CSO, clinical and research dietitian at Cedars Sinai Medical Center in Los Angeles. “Some people feel the ‘keto flu‘ intensely because they do a night and day shift with their eating. That is discouraging to feel so poorly for a few days, so people will stop right after that.”

With virtually no carbs in your system, you may even have trouble concentrating. According to the Institute of Medicine of the National Academy of Sciences, the human brain requires the equivalent of 130 grams of carbohydrate a day to function optimally—and that’s a minimum.

Your health may suffer

If you’re overweight or obese, and you have insulin resistance—and especially if you have prediabetes or type 2 diabetes—cutting way back on carbohydrates can have immediate health benefits. Your blood sugar and insulin levels will go down, your triglycerides and blood pressure may fall, and your levels of good HDL cholesterol may rise.

But the low-carb diet will also wreak some havoc. Eventually, your body needs to breakdown a mix of fat and muscle to fuel your energy needs. Losing body muscle results in a decrease in metabolism because muscle tissue burns up a lot of calories. This may be one reason that the weight often comes back after you’ve been shunning carbs for a while.

But it could impact your cardiovascular system, according to the Harvard Medical School’s review of the research. If you switch to a high-saturated-fat diet, as people do when they start eating their fill of steak and bacon, your “bad” LDL cholesterol could go up. Levels of homocysteine, an amino acid that increases the risk of heart disease, may also rise if you eat a lot of meat and too few vegetables. A low-carb diet may also increase your risk of kidney stones and other kidney diseases, according to a review of the research in the Journal of Renal Nutrition.

You’ll miss out

It’s not just that you’ll feel deprived because you’ve had to give up bread, fruit, and all the rest. According to the Mayo Clinic, your body will also be deprived of foods and nutrients that are essential for good health, including the following:

Whole grains: These protect against metabolic syndrome, type 2 diabetes, heart disease, stroke, and cancer.
Fruits and vegetables: Produce helps prevent heart disease, stroke, and some cancers. Most fruits and vegetables are very filling while providing few calories, so they can help you cut calories without deprivation. Indeed, the more fruits and vegetables people eat, studies show, the thinner they tend to be.
Beans: Rich in protein, complex carbohydrates, and B vitamins, beans have no saturated fat and lots of soluble fiber. They also contain plant chemicals that protect against heart disease and cancer.
Low-fat dairy foods: Sure, you can have butter and cream on a carb-restricted diet, but you won’t get much calcium or protein from them. Fat-free and low-fat versions of milk and yogurt are excellent sources of those nutrients.
Fiber: Getting fiber from these foods (except dairy) helps reduce the risk of heart disease and type 2 diabetes. Beans and many fruits and vegetables are particularly rich in soluble fiber, which helps lower blood sugar, curbs hunger, and lowers LDL cholesterol.
Vitamins, minerals, and health-protective plant chemicals: Whole grains, for example, are rich in components such as lignans, which may protect against type 2 diabetes independently of their effects on blood sugar. And without fruits and vegetables, you’d be awfully hard-pressed to get enough vitamin C or other disease-fighting antioxidants.

You’ll eat too much “bad” fat

The original Atkins diet became popular largely because it allowed people to eat foods forbidden on most other diets, such as cheeseburgers (without buns). More recently, the diet has been revised to include sources of healthier fats, such as fish and olive oil, and other low-carb diets have shied away from saturated fats as well. But in practice, once you stop eating bread, fruit, and beans, it’s all too easy to eat too many fatty animal foods. After all, how many foods can you take out of your diet?

If you load up on saturated fats—the original Atkins diet got as much as 26 percent of its calories from saturated fat versus the 10 percent or fewer experts recommend—it can impact your health. Saturated fats are still the major culprits behind elevated LDL cholesterol. The latest revisions to the diet, to be fair, do emphasize lean poultry and seafood, but in practice, what attracts people to this diet is the bacon and butter.

Take the good, leave the bad

The good news? Many of the weight-loss advantages of low-carb diets may have nothing at all to do with restricting carbohydrates. The main benefit may be due to the extra protein—and you can add protein to your diet even if you don’t drastically cut carbs. Protein-rich foods may help with weight control. One reason may be that protein stimulates the body to burn slightly more calories than carbohydrates or fats do.

The main reason, though, is that protein foods curb hunger better. When people eat protein-rich foods, they feel fuller longer, and when they diet, they consume fewer calories and lose more weight when they eat a lot of protein. One 2017 study in Obesity Facts found that participants who followed a high-protein diet lost more weight than those who followed a standard-protein diet.

More protein, and carbohydrates in moderation

No matter how you slice it, most people eat too many calories, and most of those extra calories come from processed carbs (so many chips and cookies!). Thus, it makes sense to cut back on those and choose lower-glycemic index carbohydrate foods instead of “fast-acting” carbs that may send your blood sugar soaring.

That way, you’ll get the benefits of a low-carb diet with none of the hazards. You’ll get the blood sugar advantages, including lower insulin levels. By eating plenty of lean protein, you’ll feel satisfied and less hungry. And by choosing “good” fats and limiting “bad” ones, you’ll keep LDL cholesterol from rising and protect your heart in the process. You’ll also discover a way of eating that you can enjoy—rather than endure—for the rest of your life. If you’re still looking for the right diet, you might want to consider looking into the perfect diet based on your body type.

Clean low carb diet

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