Do You have enough?

Let Go of the water bottle. Your plenty hydrated people

By Melissa Dahl

If you can't stomach the thought of guzzling down eight glasses of water every single day, here's some good news: You're off the hook, more health experts are saying. 

A new editorial in an Australian public health journal is the latest to bust the widely-repeated health myth we need to guzzle 64 ounces, or eight 8-ounce glasses, of water each day just to stave off dehydration. Actually, we get enough fluids to keep our bodies adequately hydrated from the foods we eat and the beverages we drink -- even from caffeinated drinks like coffee and tea. 

Turns out, the whole "eight glasses a day" thing "really is no longer the recommendation; the recommendation is drinking to thirst," explains Madelyn Fernstrom, a registered dietitian and TODAY's diet and nutrition editor. Drink when you're thirsty! What a novel idea.

It's not a bad idea to consume 64 ounces of fluid a day, but it's not a scientifically proven idea, either. It likely comes from a 1940s recommendation from the Food and Nutrition Board of the National Research Council, which said that adults should ingest about 2.5 liters of water a day. 

"But the often ignored second half of that statement pointed out that most of the water you need is in the foods you eat," explains Dr. Aaron Carroll, associate professor of Pediatrics and the associate director of Children's Health Services Research at Indiana University School.

"But that report wasn’t based on any solid evidence – it was just opinion," continues Carroll, who explored the waterlogged myth in the book "Don't Cross Your Eyes ... They'll Get Stuck That Way!", which he co-authored with Dr. Rachel Vreeman, assistant professor of pediatrics at Indiana University School of Medicine. "A number of years later, a famous nutritionist, Dr. Frederick Stare, said something similar about drinking eight glasses of water a day, but he, too, stated that it could be in the form of coffee, tea, milk, soft drinks, or even beer. He even said that fruits and vegetables are good sources of water."

But doesn't gulping down water help with weight loss? Kind of: It's true that drinking a high volume of water has been shown to work as an appetite suppressant, but consuming foods with high water content -- like watermelon, lettuce or grapefruit -- results in more weight loss than eschewing more foods for more (and more and more) water, writes the author of the Australian editorial, Spero Tsindos, of the department of dietetics and human nutrition at La Trobe University in Victoria. We've also heard that drinking lots of water helps ward off kidney stones and UTIs, but studies have shown that's only true for those who are prone to recurring episodes of either condition. 

Last summer, a paper published in the British Medical Journal grabbed headlines when it called the myth "nonsense" -- thoroughly debunked nonsense," for that matter, citing reports in 2002 and 2006 that couldn't find any "clear evidence from drinking increased amounts of water."

Yet the myth sticks around, likely because people have made a lot of money off the idea that we're all on the precipice of dehydration. (And we're definitely not -- government research on more than 15,000 people in 50 states show that over three years, the average American ingested 75 ounces of water a day, Carroll points out.)

"(B)ottled water and the entire health culture around drinking more water have been very lucrative," Vreeman explains. "Certainly, your body needs fluids and water is a healthy choice to meet those fluid needs, but many of us spend a lot of money, effort and guilt on forcing ourselves to drink more water than we really need."

So how much water should we be drinking? Whatever your body tells you it needs. Listen to your body, drink when it tells you to, and there's no need to drink more than that. (The idea that "when you're thirsty, you're already dehydrated" is another myth.) 

Fernstrom notes that it's of course better to choose water over sodas, sweetened juices or other sugary, high-calorie beverages. There may not be any evidence that excess water is doing you any good, but it's not likely doing any harm, either. 

"The issue of too much water, that's only a problem for extreme athletes who are sweating profusely and drinking too much water without replacing their salt," Fernstrom explains. For us mere mortals, if you drink lots of water throughout the day, "you're just going to pee it out," she says. "The worst that'll happen is you'll learn where more bathrooms are in your community."