Water has negligible thermogenic effect

Have you ever seen the guys in the gym that carry around gallon jugs of water? Do they know something the rest of us don't? Is a drought coming or something? Or could it be that drinking more water actually burns calories?

The answer to this question is Yes and No. German researchers found that drinking 500 milliliters of water (about one pint) increased resting metabolic rate by 25 percent (which pretty much works out to be 20 extra calories for 60 minutes). Water ostensibly increases calorie-burning by diluting the blood flowing to the liver and by activating the sympathetic nervous system. This activation leads to an increase in caloric expenditure. So ... that was the Yes part of the answer.

The No part of the answer is that the amount of calories you burn by drinking an excess of water is negligible. To put it in perspective, you can burn 20 calories washing your dishes. In addition, drinking too much water can be dangerous, as it may cause hyponatremia, which can be fatal.

When it's all said and done, my guess is that the guys toting the gallon jugs of water at the gym are just plain thirsty (and smart enough to know that the water coming out of the fountain, unlike the water in their gallon jug, is likely filled with chlorine).