Working aerobically on your abdominal muscles for over 7 minutes stimulates the capillaries in this area. These in turn increase the blood flow. A greater blood flow means a greater flow of oxygen – and fat only burns in the presence of oxygen. Toned muscles need more calories (kcal) to stay active. Our organism tends to release these calories from the area nearest the muscle, in this case the waist area.
Please watch: "Chest workout – best home routine to kill pec muscle calisthenics and bodyweight"