The molecule of H2O being water what percentage is that? Well for men it's of adult age. 17 to 40 ish. That's your age group. Yeah so 17 percent water you're in trouble. My bad. If you're a male age between 17 and 40 your percentage of water is around about 60 percent. Why is it less? Because on average the body fat composition. Forget all here Michael. The body where this is I'm just stating the science we maintain a relatively constant balance of fluid. Around depending on one whether you're male or female two whether you're an infant or older your body fluid percentage. Percentage is different.