Nutrition Experts Bust 10 Myths About Hydration

Updated: Apr. 15, 2024

Mindlessly drinking eight glasses of water or chugging Gatorade during workouts won't necessarily meet your hydration needs. Here, doctors bust some myths about how to make sure you're H20-healthy.

Woman drinking from bottle of water

Myth: If you’re thirsty, you’re already dehydrated

Actually, your thirst sensations are a pretty sensitive gauge of your fluid levels. “Dehydration is the body’s natural loss of water through sweat, tears, and breathing. The kidneys control the water balance in the body, and when they sense the need for more water replacement, it sends a message to our brains to drink more water by making us feel thirsty,” explains kidney specialist Dara Huang, MD, founder of New York Culinary Medicine. (By the way, make sure you’re not always thirsty for these reasons.)

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Two glasses of water with pitcher

Myth: Drink eight glasses of water every day

No question that drinking enough water is important. But the eight glasses advice is a myth, says Dr. Huang, and it can be dangerous. “If your heart or kidneys is compromised, drinking too much water can cause congestive heart failure, pulmonary edema, or water intoxication. In these cases, fluid intake should be limited,” she explains.

To figure out the magic ounce-count of aqua that your body needs, you should take many factors into consideration, according to Roger E. Adams, PhD, doctor of nutrition. “This number may be too much for some and not even close for others, especially if you are a heavy sweater, or simply larger. The larger you are, the more water you need for every function in your body, not to mention replacing sweat. However, if you are smaller or don’t sweat a lot, even less than eight glasses may suffice to maintain water balance,” he notes.

When in doubt, talk to your primary care physician for their expert opinion.

Here’s How Much Water You Really Need in a Day, with Nutritional Scientists’ Latest Wisdom

Woman sitting on edge of bed drinking glass of water

Myth: Always drink water first thing in the AM

You’ve heard it before: “Start your day with a full glass of water.” While you might be thirsty and you might naturally reach for that, Dr. Huang says it’s not necessary. “If you have normally functioning kidneys, it may be refreshing to reach for water, but it’s not vital,” she notes. “Some people think that if you go to sleep at midnight and wake up at 8 a.m., you’ve gone at least eight hours without hydrating, so you have to drink water. This isn’t the case. And your urine can give a glimpse too: Your urine is clear because it’s diluted. If your urine is dark, it’s because your kidneys are doing its job to conserve water and it’s concentrated. The first void of the day is usually the darkest,” she notes.

Is It Bad to Drink Water That’s Been Sitting Overnight—Or Longer?

Glass of coconut water next to two halves of a coconut
Carla Castro/Shutterstock

Myth: Coconut water is the best recovery drink

Yes it’s trendy, and it’s supposed to replenish you after a night on the town or a tough workout. It does contain fewer calories than other potassium-rich fluids—but it’s not always your best option, says Dr. Huang: “To prevent dehydration, drinking plain water is just fine. And it’s important to know that coconut water is not for everybody. It can cause dangerously high potassium levels in those who have kidney disease and should be avoided.” When in doubt, start with water and then speak with your doctor if you still feel dehydrated.

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Woman athlete drinking from plastic bottle of water

Myth: You can’t overhydrate

You know what they say about too much of a good thing, right? It actually becomes a bad thing, and the same is true for H20. People tend to think that you can’t drink too much agua—especially novice runners, says Adams. The truth is you can, and it can be lethal. “A condition called hyponatremia, is a result of ingesting too much water thusly causing a decreased concentration of sodium in the body. This can lead to confusion, convulsions, and even death, especially when running,” he shares.

Pouring water into a glass

Myth: Water is all you need

You can go longer without food than you can without water, but Adams is quick to note that sometimes good ole’ fashion H20 doesn’t give your system all it needs. Take into consideration how much activity you’re doing, he says, how hot it is outside and how much you’re sweating. “Water is a great fluid replacer for most people, but it isn’t the perfect way to regain water balance for everyone and in every situation,” he says. “Higher amounts of electrolytes are lost when sweat rates increase during longer events or activities in hotter climates. A 10K run in a hot area of the country demands more electrolyte replacement than a walk in chilly temperatures.”

Which Type of Water Is Right for You? Here’s How to Choose

Sports drinks in cooler
Chuck Wagner/Shutterstock

Myth: Electrolyte-enhanced drinks are best

Ever wondered where Gatorade comes from, especially now that this electrolyte sports drink and its ilk have cornered the rehydration market? It’s an interesting story, but you may want to think twice before reaching for these popular beverages, according to Tania Dempsey, MD, from Armonk Integrative Medicine. You don’t always need one after light activity, and some of the ingredients can be questionable.

“The hydrogenated oils they use—particularly brominated vegetable oil, which was taken out of Gatorade but is still present in Powerade—can be harmful to the thyroid,” she explains. (Note that most manufacturers have removed or are planning to remove the ingredient.) “Also, the sugars found in these sports drinks are unhealthy. Powerade still contains high fructose corn syrup, which has been linked to type 2 diabetes. Gatorade recently switched to sugar and dextrose, which might sound better than HFCS but is equally problematic in causing the blood sugar to rise drastically.”

Hydrate the healthy way with one of these 7 best nutritionist-approved electrolyte drinks, or try a plant-based hydrating mix like Healthy Editor favorite Cure.

Two sets of hands holding cups of coffee
Africa Studio/Shutterstock

Myth: Caffeine causes dehydration

That daily cup of Joe in the a.m. might be the only thing that ensures you get to your morning planning meeting, but is it drying out your system before you’ve even had a bite of breakfast? According to Adams, the commonly-held belief that coffee makes you dehydrated is plain wrong, especially for the casual coffee or tea drinker. Although large doses of caffeine alone can dehydrate, the water in your coffee and tea more than make up for any dehydrating effects, he explains.

If you’re looking for another healthy way to hydrate while you get your morning pick-me-up, try looking to a refreshing energy seltzer like Hiball’s, which gives you a natural boost from organic caffeine, guarana and ginseng, or Odyssey Elixir’s, for mushroom-powered energy and focus.

Woman runner tying sneaker next to bottle of water

Myth: Only drink extra during exercise

If you think sippin’ on a diet coke or tea is enough to keep you hydrated because you don’t work out frequently, you might be missing out on some much-needed agua-induced nutrition—and make sure you know the subtle signs of dehydration. Adams says that many people think they only need water when they’re working up a sweat, but this habit can lead to mild dehydration during the day. Instead, he suggests drinking water throughout the day to make it your go-to beverage: “This is a simple way to ensure you are getting water all day long; not just when exercising. You need water for daily functions, so provide for that and you will ensure hydration the rest of the day,” he says.

Cup of urine
Mac Nishimura/Shutterstock

Myth: The color of your urine is the best hydration check

Yes, says Adams, the color of your urine can be an indicator you need to chug, but there are other important indicators. Plus, if take multivitamins or are on a high-protein diet, the color could be dark for reasons other than dehydration. “Instead of just looking at the color, look at volume. The more you put in your body, the more that should come out. If you seldom go to the restroom, that’s a sign you are probably not consuming enough fluids,” he explains. “On the other hand, if you are running to the restroom every 15 minutes, you may be over-consuming fluids.”

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