It's simple math... the more you put in your body, the more you have to burn off. Whenit comes to losing lbs and inches its %75 diet and %25 exercise. But its the exercise that helps you keep it off.
But be careful, cut too many calories out of you diet will slow your metabolism and cause you to lose muscle mass. You should aim for 10 calories per pound, per day.
So... like me, I'm 140 at my heaviest... so 1400 calories a day for me.