Actually, masturbation, like any physical activity that involves movement and an elevated heart rate, burns calories, I read somewhere that it's about 100 calories average, depending heavily on the duration of it, It isn't a major amount, but every bit helps. I wouldn't make it the central premise of a diet though, like oh I'm fat, I'll just start jerking off more. if you are not doing anything about food consumption and regular exercise, you're going to fail.