first of all, im only 15 but i want to have a leaner and firmer body (it's like when you wear a fitted shirt, it will look good and the chest is flat. THAT'S ALL! ^^) so, i am doing aerobics(not only for my body to look good, but also for me to have an activity). but after i exercise, i am really really hungry so i eat and even if i try not to eat many, i can't stop it. also, my weight is not decreasing and it's like increase and decrease. so what should i do?