How much is too much hydration?
As a regular feature of CNNhealth.com, our team of expert doctors answers readers’ questions. Here’s a question for Dr. Gupta.
From Dayna in Pineland, Texas:
“I have been recently ‘diagnosed’ with dehydration. I’m drinking more now and have much more energy, but wonder: How much liquid consumption is too much on a daily basis?”
Dayna, there is no single right answer here. First I’m glad you saw someone about your lethargy and you are taking action to feel better and improve your health.
According to the Mayo Clinic, an average adult loses more than 80 ounces of water every day. The normal person can easily replenish this by eating and drinking a healthy diet. But if you eliminate more than you bring in, due to illness or exercise, that is when dehydration can occur.
As to your question; Your height, weight, where you live, how much you exercise and many other factors determine your need for fluids. However, you probably have heard to always drink eight glasses of water a day. And the American Dietetic Association says to drink at least 64 ounces of fluid a day – eight 8-ounce glasses. But you do get some hydration from your food as well, so it’s safe to take that into account.
You are right to consider how much water is too much because you can over-hydrate. There is a relatively uncommon condition called hyponatremia. This can happen in endurance athletes who are losing sodium through sweating and drink only water to re-hydrate. Most experts will say the key to proper hydration is listening to your body – drink when you’re thirsty.
A good way to check if you’re drinking the right amount of fluids when exercising is to see whether you weigh the same after your workout as before. If you weigh less, you need to hydrate, but if you have gained weight you need to back off.
Another tip, if you are well hydrated your urine should be nearly colorless or pale yellow. Also, keep in mind that thirst is often misinterpreted by the body as hunger, so make sure to drink some water at every meal.
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Odds are now that it’s so stinking hot out, you drink more water on a regular basis to keep yourself from being dehydrated. But, it turns out, you can overhydrate, too. Overhydration is exactly what it sounds like: It occurs when you take in too many liquids, and it can be a serious condition. “Now that it’s summer, everyone is obsessed with dehydration, but if you work out strenuously and are chugging lots of water, overhydration should also be on your radar—especially if you’re a woman,” Karen Ansel, R.D.N., author of Healthy in a Hurry: Simple, Wholesome Recipes for Every Meal of the Day, tells SELF.
Here’s why it’s such a big deal: Overhydration can cause a condition known as hyponatremia, which happens when the sodium levels in your bloodstream become unusually low. You need a healthy amount of sodium in your bloodstream to help your cells hold on to water, but when you drink too much water, your sodium levels become diluted and your cells become waterlogged, explains Ansel. As a result, you can end up feeling nauseated, confused, run-down, and irritable, according to the Mayo Clinic.
While you’re more likely to be dehydrated than overhydrated—especially in the summer—overhydration is still serious when it happens. In addition to making you feel like crap, it can also cause seizures and put you into a coma if it’s not caught in time.
Athletes should be extra careful, Marc Leavey, M.D., an internist at Baltimore’s Mercy Medical Center, tells SELF: “There are a scattering of cases seen among athletes, runners, and those exercising and trying to consume extra water.”
But even if you’re not an athlete who regularly trains outside, it’s worth being wary of overhydration whenever you’re exercising outdoors during the summer. “Drinking too much water when you’re exercising in hot, humid weather creates the perfect storm for hyponatremia because you’re losing sodium through sweat and further diluting your blood sodium with water,” Ansel says. “If you’re a woman, you’re even more susceptible to overhydration because female hormones can interfere with the body’s sodium balance.”
It sounds like a simple enough issue to avoid—just don’t drink too much liquid—but Jessica Cording, a New York-based R.D., tells SELF that it’s not always that easy. “You need to listen to your body, but it’s really hard to tell when you’ve had enough water when it’s hot out,” she says.
It’s tough to say what your liquid cut-off should be, since factors like your size, activity level, medications you’re taking, and how hot it is out impact how much you should be drinking, Leavey says. The best way to minimize your risk is to take your time when you drink liquids and listen to your body’s thirst signals. “If you’re thirsty, then go ahead and drink up, but if not, you don’t need to obsess about it,” Ansel says. If you’re working out in the heat for over an hour, she recommends having a sports drink with electrolytes to keep your sodium levels in check.
If you suspect that you’re overhydrated or on the cusp of it, Cording recommends limiting the amount of fluids you drink and eating something salty. If you still feel crummy or your symptoms start to get worse, Leavey says it’s time to seek medical attention right away.
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Hydration Confusion: How Much Is Too Much?
With a recent study about over-hydrating in the New England Journal of Medicine catching so many headlines, don’t feel bad if you’re more confused than ever about how to hydrate during long-distance events.
After being told for years to drink up to prevent dehydration, now athletes are being warned about the dangers of drinking too much.
The NEJM study tracked 488 participants in the 2002 Boston Marathon and found 13 percent finished the race hyponatremic, when blood sodium concentration drops so low it can cause severe brain dysfunction, including seizures, coma and even death.
At greatest risk were extremely thin runners who gained a lot of weight during the race (4.5 to 11 pounds) and finished in more than four hours (longer finishing times mean more time to take in fluid).
Women at Greater Risk
Although the researchers didn’t find gender, in itself, to be a significant risk factor (unlike what earlier studies had suggested), they did determine that body size matters. And since women tend to have less body mass than men, they may be more susceptible to hyponatremia than men are.
“I personally think it’s purely a size effect. Women are more likely to develop a fluid overload simply because it takes less fluid for smaller people to become overloaded,” says Lewis G. Maharam, M.D., the medical director for the Rock ‘N’ Roll marathons and the ING New York City Marathon.
Maharam also warns that taking pain medications such as ibuprofen (Advil, Motrin IB, Nuprin) and naproxen sodium (Aleve) during endurance events may increase the risk of hyponatremia. “A big part of the problem is the inability of the athlete to excrete the excess fluid because of high levels of fluid-retaining hormones ADH and AVF.” NSAIDs (non-steroidal anti-inflammatory medications) decrease blood flow to the kidneys, thereby increasing ADH and AVF.
Know Your Sweat Rate
The answer to successful and safe hydration is balance. Keep in mind, dehydration is still one of the biggest risks in endurance exercise, but the key to performing at your best is drinking smart, not gulping liquids.
The best way to avoid drinking too much or too little is to take in about the same amount of fluid as you sweat out. Here’s how to figure out your sweat rate:
- Weigh yourself without shoes or clothes, and record it in your log, noting temperature and humidity.
- Work out for one hour.
- Dry off and weigh yourself, noting the weight lost. Also note any fluids you may have taken while running.
- Use the following formula to determine your hydration needs: One pound lost = 16 oz. of fluid.
So, if you lost two pounds in that hour, you should replenish 32 ounces of fluid (about 8 ounces every 15 minutes) in the same temperature and humidity level.
Do this test a few times in different conditions to get a sense of how your hydration needs change in varying temperatures and humidity levels, and intensity levels.
Tips for Smart Hydration
To make sure you meet, but don’t exceed, your hydration needs:
- Set your watch alarm to remind you when to drink.
- Aim to replenish 80 to 100 percent of fluids lost.
- Avoid gaining weight (a sign of over hydrating).
- Consume a sports drink with electrolytes (sodium, potassium, etc.) during your training sessions and in races longer than 60 minutes. Plain water is fine for workouts shorter than 60 minutes, but longer sessions require a sports drink to replenish electrolytes and energy.
- Flavor your meals with salt right before long workouts and races to boost electrolyte levels.
- Avoid drinking more than usual during race week. This will dilute your blood sodium levels, putting you at higher risk of developing hyponatremia. Your fluid needs drop during this taper week. So, drink normal amounts of fluid and use the urine test to determine if you’ve had enough: If it runs pale yellow, you’re well hydrated and ready to race.
Jenny Hadfield is the co-author of Marathoning for Mortals (Rodale, 2003) and the Penguin Brigade Training Log (Breakaway Books, 2003). She’s also coach for the John Bingham Racing Half Marathon Series. For more information on Jenny visit www.jennyhadfield.com.
The Earliest Signs You’re Drinking Too Much Water
Even though we’re constantly reminded of the benefits of staying hydrated, drinking enough water can be a tricky business. The same is true even after you’ve become one with your water bottle—once it feels like an appendage, it can be difficult to put it down. After a while, you may start to wonder if you’re hydrating properly or going overboard.
“Drinking too much water can result in a condition called hyponatremia, which is a dangerous drop in blood sodium levels,” says Kristin Koskinen, RDN, registered dietitian in Richland, Washington. (Sodium is an important electrolyte that acts as the body’s traffic guard, regulating where water is being distributed throughout the body and how much is being sent to the bladder.) “Though it’s relatively uncommon to attain water intoxication, it can happen if you outdrink what your body can excrete,” says Koskinen.
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Here are the earliest symptoms to look out for, and how to hydrate like a pro.
The Subtle Signs of Over-Hydrating
Monitoring the color of your pee—and how often you run to the throne—are the earliest ways your body alerts you of your hydration status, says Koskinen. Urine color typically ranges from pale yellow to tea-colored, thanks to a combination of the pigment urochrome and the amount of water you drink, according to the Mayo Clinic. If your pee is clear more often than not, that’s a sign that you’re either drinking too much water in too short a timespan and need to spread out your efforts, or you’re taking in too many fluids overall.
This is especially the case if you notice that you’re going to bathroom more than usual. “On average, people urinate 6-8 times a day, though going up to 10 times a day is within the realm of normal for the water-drinking high-achieves,” says Koskinen. (Or for those who regularly take in caffeine or alcohol.) If your job or day-to-day activities are compromised by the uptick in bathroom trips (say, going every couple of hours or more) and your pee is clear, then you may want to consider cutting back in the liquids department.
When slightly decreased, low sodium levels may not cause noticeable symptoms, says Suzanne Dixon, RD, registered dietitian with The Mesothelioma Center in Portland, Oregon. But when they continue to drop due to drinking more than your body is capable of excreting, it can cause symptoms like bloating, headache, brain fog, and nausea. “The kidneys have limitations of how much water they can excrete at a time, which is a maximum of 800-1,000 millileters per hour,” says Koskinen. “Anything that exceeds that amount essentially waterlogs the body.” Enter bloating.
When the body can’t rid itself of excess water, cells swell to accommodate it—and because the brain is enclosed in the skull, it leaves almost no room for any expansion, says Koskinen, which can cause headaches and brain fog. You may also feel nauseous if your body’s water-to-sodium ratio is out of whack—when there’s too much water in the bloodstream, your body might try to throw up the excess water in order to find balance again, says New York-based registered dietitian Jackie Arnett Elnahar, RD.
Currently, there isn’t solid data on exactly what level of sodium in the blood causes these early symptoms—it probably varies from person to person, Dixon says. Fortunately, for the average person, drinking too much water usually leads to nothing more than an increase in bathroom breaks. But if you do find that you experience the above symptoms on occasion and want to know if your hydration habits are the culprit, revamping your relationship with water can help you solve the mystery.
How to Find Your Hydration Sweet Spot
The best place to start is to estimate how much water your body needs on average. “I recommend starting with a half-ounce of water per pound of body weight,” says Koskinen. “Because muscle carries more water than fat, leaner people may stick closer to this number and those with more body fat may ratchet down, while people who are overweight or obese may want to use their ideal body weight in this calculation.”
Many of us guzzle a set number of glasses per day to reach our H20 goals, which is a good way to get past your perma-parched ways in the beginning—but because hydration levels fluctuate day-to-day based on the weather, how hydrating your diet is, how active you are, and other bevvies you sip along the way, the amount of water you drink to fill in the blanks should be adjusted accordingly so as to not overdo it.
One of the easiest ways to fine-tune your hydration habits is to stop looking at it as a water-centric practice, and instead shift your focus to include fluids as a whole. “Fluid doesn’t just come from water, but from any beverage you drink, as well as many foods,” says Koskinen. (Roughly 20 percent of daily fluid intake usually comes from food, and the rest from drinks, according to the Mayo Clinic.) If soups, fruits and veggies, and smoothies are a regular part of your diet, then you might not need to replenish as often—the same goes for foods that melt at room temperature or are held in a gel matrix (think: Jell-O or pudding), she adds. Meanwhile, on days when you’re a sucker for anything salty (ramen, frozen dinners, fast foods, chips), an increased water intake may be required so the body can maintain equilibrium.
Nearly any beverage can count toward meeting your daily fluid needs—including coffee. “If a person is a habitual caffeine consumer, their body adapts, and the coffee stops acting like a diuretic,” says Dixon. “However, if you’re not a regular caffeine drinker, then these fluids are considered dehydrating and shouldn’t be counted toward your daily fluid intake.” The drinks that never contribute to your hydration quota? Alcohol and energy drinks, says Dixon. Alcohol causes your body to lose more fluid than you get from the beverage itself, while heavily caffeinated energy drinks may have so much caffeine in them that they also act as a diuretic.
During hot or humid weather, your body’s need for water may increase—the same is true if you live in dry climates, whether it’s hot or cold, says Koskinen. And if you’re super-active or athletic, weighing yourself before and after long, intense workouts (sans clothes) can help you replace fluid losses as accurately as possible: “The difference between the two weights give you a good approximation of what your fluid losses were,” says Koskinen. For every pound you lost over the course of the workout, drink around two cups of water (or a sports beverage) to replenish, and try to do so over the next several hours following the workout.
The Secret to Hydrating as You Go
Though calculating your fluid needs isn’t an exact science, your body will tell you straight-up whether or not you need to hydrate. Your pee should be a pale yellow color—if it’s darker, hit the water cooler, and if it’s lighter, hit the brakes. “During normal daily activity, drinking one or two cups over the course of an hour should keep you hydrated without overtaxing the kidneys,” says Koskinen. The decrease in bathroom trips is just an added bonus.