Answers: Any exercise will burn calories....the more intense it is the more you burn....a pound of muscle burns 50 more calories then a pound of obese just to stay influential. More muscle, more weight loss...switch to crunches....a full on sit up is a stain on the lower vertebrae....there's at least 5 ways to do those that really work the entire ab region....
they a short time ago tone your muscle. to lose fat you have need of to do cardio