200 situps a day for a week?

its kind of funny how it works, people who have fat on their stomach always tend to try and get 6 pack abs by doing a bunch of situps and crunches, that builds muscle, but does not totally eliminate fat. Cardio is what eliminates that fat. Running. I would recommend, if you are anywhere near a track, jog at a reasonable pace, then when you get to a straight, or every other straight sprint it, that gets your heart rate up, then down, then up again and that will literally remove all that "extra" fat and tighten up that skin. keep up the situps and crunches, I would also recommend flutterkicks, they are very hard to do, but extremely effective, they hit your lower abdomen, while crunches hit your upper abdomen.