There are tons of theories about what proper hydration can and can’t do for the body. People have claimed it can make skin look plumper or more radiant, that it can prevent cancer, and even that it can protect against COVID-19. While the scientific evidence for all of these effects remains mixed, one thing is clear: The human body does not like to be low on water.
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“If we’re not hydrated, then our body is in a state of stress,” says Melissa Majumdar, M.S., R.D., dietitian at Emory University Hospital and a spokesperson for the Academy of Nutrition and Dietetics. “And we do know that states of stress can lead to chronic disease.” When you’re chronically dehydrated, your body will release the stress hormone cortisol, and that can impact weight, blood sugar, and even cardiac function. Coming off a landmark year of stress, one could argue there’s never been a better time to drink up.
Enter: Prevention’s 7-Day Hydration Challenge. You’ll learn how to use the science behind hydration to your benefit and pay attention to your own body as it signals what it needs. Check back here every morning at 9:30 a.m. for a new task, and a mere week from now, you’ll have everything you need to become your best, most hydrated self.
Your first goal is to hydrate by drinking and eating mindfully. An egg is a great place to start, because it’s cheap, healthy, and it starts out as a liquid before you cook it.
But wait, let’s back up for a sec. Where did our fascination with how much water to drink per day originate—and why is there so much confusion about it?
While not a myth exactly, the recommendation to drink eight glasses of water a day isn’t supported by any rigorous science. Researchers believe it stems from a 75-year-old report that has been repeated so often it has simply become canon. Back in 1945, the U.S. National Academy of Sciences Food and Nutrition Board recommended consuming 1 milliliter of fluid for every calorie eaten. If you consume a diet of about 2,000 calories, that comes out to 8 and a half cups of water a day.
Beyond that, experts will say it depends—on how active you are, how hot it is where you live, and even how “salty” you are (more on that later).
The good news is, that same Food and Nutrition Board bulletin said that a substantial portion of dietary water can and should come from foods and drinks. “Fruits and vegetables, yogurt, even foods that are made with fluid like hot cereals, rice, and pasta, count because they’re absorbing fluid as they cook,” says Majumdar.
Gallery: 10 Side Effects of Drinking Soda Every Day (Eat This, Not That!)
The most recent government recommendations on hydration, a 2004 report backed by eleven researchers from the Institute of Medicine of the National Academies, say that well-hydrated men tend to consume about 3.7 liters of fluid a day, and well-hydrated women consume about 2.7 liters (or 11.4 cups) . But you don’t need that amount in pure water.
We know it would be satisfying if, to kick-off this challenge, we gave you an exact amount of water to drink per day. But that would be doing you a disservice. Rather, today’s challenge is to disassociate guilt from daily glasses of pure water consumed and make sure that you get fluids from lots of sources—fruits and vegetables, coffee, tea, juice, and even soda—in addition to water.
If you want more guidance throughout the day, the experts who wrote the aforementioned report agree: Check in with yourself. Are you thirsty? If yes, you’re probably a little dehydrated, so drink up. If the idea of downing water right now doesn’t feel right, set a glass of water nearby and you’ll likely pick it up when you’re ready, without even thinking about it.
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soda art with bubbles
Today’s challenge is to hydrate without relying on sugary drinks. And it’s not just about the sugar itself—making good choices about what to drink is easier if you understand a concept called osmolality. It’s an interesting way to think about hydration (and bonus, is pretty fun to say).
All human cells need appropriate concentrations of water, potassium, and sodium both inside and outside to work properly. One way to measure those proportions is to determine how concentrated the fluids in your body are. A scientist can take blood serum or urine, separate out all the solids (such as salts, sugars, and minerals), and then divide the total amount of those solids by the total amount of fluid. The resulting number is a measure of osmolality.
While, yes, any non-alcoholic beverage provides hydration, how quickly the fluid gets into your cells may come down to how concentrated your drink of choice is. “The blood is around 290 or 300 osmolality, and many of the drinks that are sold to us in stores are over that. Some of them are really high, like 1,200 for cranberry juice. In order for these things to be absorbed, water has to come out of your body into the intestine to dilute it down until the gradients are right,” says Jodi Stookey, a nutrition epidemiologist at Arizona State University.
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Forget the idea that you need eight glasses of water a day, and use this science-backed guide to drink more water for optimal hydration.
While a beverage’s osmolality doesn’t have major effects for hydration, it can affect how quickly liquids get into your system, and it can also be a good proxy measure for high calories. “I think of it as ‘this is a concentrated drink’ and ‘that is a dilute drink,’” Stookey says. “And the sugary drinks are in the group with the concentrated drinks.”
So today, while, yes, you can get some hydration from sodas and other liquids, aim to drink a greater amount of flat or carbonated water—with a squeeze of citrus juice if you’d like, for taste.
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