It's true. When you go crazy burning calories, you have to eat a bit more than you normally would. Your body is crazy good at adapting, so if you give it a huge calorie deficit all the time, your metabolism will get better at conserving fuel and running hard on less calories. it sounds weird, but I swear it's true. That's one of the truth bases behind "cheater" meals. Tossing in higher calorie days every once in a while keeps your metabolism from becoming set to run on very low energy stores.