You body cannot efficiently change carbs into energy without ample water. And, according to the Journal Physiology of Sport and Exercise, you can't deliver essential amino acids to muscle tissue without adequate water, either. Not only will your workout sessions suffer, but insufficient liquids in your body will also hinder fat breakdown.

Don't wait until you're thirsty-thirst signals the first stage of dehydration, which means you're already too late. You must stay hydrated. Drink often throughout the day, and especially before and during a training session. Try to get at least 10 cups of water per day, although up to a gallon is okay.