HoneyB

Crunches do help shape your mid-section althoug the key to losing fat is by incorporating some cardio workouts in your routine. A low-moderate intensity workout like jogging for 30-45min 3 times a week should help a lot. Another type of cardio that is easy is jumping rope, apparently 10min of rope jumping should burn as many calories as jogging.
As for the crunches, they do help, the good thing about that is that you don't need 100 of them, as long as u do it correctly you only have to do about 20-30. An awesome and effective way to do so is simply lying on your back and lifting your legs up towards the ceiling (keeping them together), doing about 25 reps never touching the floor. It might be a little tedious but it works and doesn't take up too much time.
Diet is another key factor, at the very least make sure you drink at least 10-12 8 oz. glasses of water daily. keeping yourself hydrated is crucial and will help curb your appetite. If you have a stressful job and don't have time to eat well you can always keep a few fruits or nutritional bars on you so they are there to grab if you start to feel hungry and keep you somewhat satisfied until you get home and cook a good meal.
I hope this somewhat helps!