The body does not burn body fat from a certain area when you exercise. If you want "six pack abs" or "reduce some inches" around the middle abdominal exercises won't do the trick by itself. Visualize a spring mattress. The springs are your ab muscles. The ab exercise work those muscles. On top of the springs is a layer or two of padding. That is your body fat. Lots of crunches tighten the springs but do not reduce the padding. You need to burn the body fat through nutrition and exercise.