Hmmm....

'Pummeling your stomach with hundreds of repetitions of ab exercises doesn’t achieve what you think it should. Here’s why:

Since it takes around one minute to do roughly 20 repetitions of an ab exercise, you are spending up to one hour a day exercising your core. The fact that your muscles are rock solid is testament to the fact that you are stimulating the area and that your muscles are responding. Your six pack is there, but the fat is obscuring it. And all those ab moves won’t touch the fat. So, many people blast away at their abs thinking that the burn that they feel is zapping off fat. It’s not.

Abdominal exercises burn only slightly more calories than lying on your back and not moving at all. And there’s no evidence that what calories these exercises do burn results in spot-specific fat loss in the area. One classic study at the University of Massachusetts found that men who did 5,000 sit-ups a day did not decrease the size of the fat cells in the torso and they did not reduce waist size'

Full story here.