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Drink Wisely During Exercise

Too Much Fluid Can Be As Bad As Too Little

So How Much Should You Drink?

Not everyone goes quite so far. Other experts who spoke with WebMD agree that it's terribly dangerous to drink too much water or too many sports drinks. But they are uneasy about dehydration.

The USA Track & Field association web site carries advice from Noakes and Douglas J. Casa, PhD. Casa is director of athletic training education at the University of Connecticut.

"I'd bet many more people running Atlanta's Peachtree Road Race were dehydrated than overhydrated," Casa tells WebMD. "I am not downplaying hyponatremia. But the advice of don't drink the water is not good advice for soccer and football players and runners who are out there sweating."

Casa stresses appropriate fluid replacement. So does Leslie Bonci, MPH, RD, director of sports nutrition at the University of Pittsburgh Medical Center. Bonci is the nutritional consultant for the Pittsburgh Steelers and Panthers as well as for the Pittsburgh Ballet Theatre.

"It is not one size fits all," Bonci tells WebMD. "Each and every person doesn't need same amount of fluids. Not everybody has the same sweat rate, the same sodium loss rate."

Safe Use of Water and Sports Drinks

So how do you know how much to drink?

"The solution is not to drown oneself," Bonci says. "Just water alone is not going to be the best recommendation. You also need something with some carbohydrate and some electrolyte in it. So water alone during exercise, no. Drinking until you slosh or drown, no. The guidelines are 20 ounces of fluid before exercise, and over the course of every hour of exercise drink between 28 to 40 ounces of fluid. That is not enormous quantities."

Casa has a simple rule. The next time you set out to exercise, weigh yourself before going out. When you get back, step on the scales again. If you lost weight, you should drink more the next time. If you gained weight, you should drink less.

How much more or less? It's easy if you have a metric scale. For every kilogram you lose (or gain) during exercise, you need a liter more (or less) fluid. If you don't have a metric scale, it's one liter of fluid per 2.2 pounds.

And don't forget salt, Bonci notes. It's also a good idea to know your individual rate of salt loss. That can only be measured in a sports clinic. But there's an easy way to tell if you lose a lot of salt when you work out.

"Some people are truly greater salt losers than others," Bonci says. "Those whose sweat stings their eyes, those who get that crust on the skin, should not put all their faith in sports drinks. Their salt should be from food. Those who lose salt have to be more vigilant about adding maybe some extra soy sauce to their meal the night before. And they have to be careful about not overdoing it on fluids."


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