Ask Men's Fitness!

Q: I've heard a bunch of different numbers being thrown around lately about how much water you should drink every day. What's the lowdown - eight or 10 glasses maybe?

A: Yeah, we're going to pour some cold water on that myth right now. The eight glasses a day figure that's always thrown around in health blogs and on TV is an erroneous number thought to have originated from a statement from the Food and Nutrition Board of the National Research Council in 1945. It said adults should drink about 2.5 liters of water per day, which equals out to about eight 10-oz. glasses of water.

But sticking to some specific amount based on generalities isn't what you should be focusing on, says Josh Axe, C.N.S., a nutritionist and consultant to the U.S. Olympic swim team. "I typically recommend that people take their body weight, cut that in half, and drink that equivalent number in ounces every day," Axe says.

This means that if you're 180 pounds, you should drink at least 90 ounces of water on a daily basis. However, everyone is different. Other factors that impact how much water you should drink include body size, activity level, climate, diet, and other beverage intake, and medical condition.

Adequate water intake is important for a host of body processes, including muscular activity, temperature regulation, and the transporting of oxygen to our cells; but getting the proper amount and not overdoing it is just as essential, especially when exercising. A 2011 study of Chicago marathoners published in the British Journal of Sports Medicine noted that it's currently estimated that 0.3% - 13% of marathon runners finish the race overhydrated.

The study found that 9% of the marathon runners participating in the study reported drinking as much as possible during the race. Overhydration, or hyponatremia, can lead to muscle cramps, nausea, seizure, and in rare cases, death, so keep your body in tune, use our formula, and keep in mind your specific circumstances, which may impact your appropriate water intake to stay properly hydrated all day long.

(Some information for this article was provided by FIJI Water.)