Hi, I thought that I could help you. I think that to help you get a flatter stomach sit ups are only part of the solution. They do exercise that muscles but they won't help you lose any fat over the muscle. To do that you need to do cardio exercises like running or walking to speed up your heart, this is when you are burning fat. And it will burn fat from all over, not just on your stomach. If you want to be healthy you should also try to drink lots of water and milk, and eat 3 or 4 fruits and vegetables a day.