Hand to mouths, there is no exercise that breaks down fat. Its all about diet and an overall good exercise program. The body stores fat when you eat to much and burns the fat for energy when you are in a calorie negative state.
No amount of any abb workout will cause you to loose abdominal fat, unless you do like 1000 situps a day. But then your not really losing the weight from the situps. Your losing it from doing a cardio program that focuses on abdominal exercise.