How Much You Really Need to Drink When Exercising

 “8 glasses of water per day” advice, but what about when part of that day is spent exercising … in the heat … under the blazing summer sun?

Well, first of all, it’s worth realizing that the common hydration recommendation of 8 glasses of water per day (8 ounces each) – totaling 64 daily ounces – is actually slightly off. After all, the National Academy of Medicine recommends that women get 2.7 liters (about 91 ounces) of water per day and men get 3.7 liters (about 125 ounces).

However, as Joy Dubost, a New York City-based board-certified sports dietitian, notes, about 20 percent of that should actually come from foods. That puts baseline beverage consumption at about 73 ounces for women and 100 ounces for men.

Then, of course, once you add in exercise, fluid needs only increase.

We lose fluids during exercise primarily through evaporation via sweat and through respiration,” says board-certified sports dietitian Kelly Pritchett, assistant professor in nutrition and exercise science at Central Washington University and a spokesperson for the Academy of Nutrition and Dietetics. She explains that the average person loses about 17 to 50 ounces per hour when exercising.

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