Flattening your stomach requires a full-body approach to lower your body fat. Aside from a healthy diet, cardiovascular exercise and strength training, you have to perform a variety of exercises that target your abdominal muscles. Reverse sit-ups are the opposites of traditional sit-ups. Instead of your upper body, only your lower body moves. The exercise focuses mainly on the lower abdominal muscles and is therefore ideal for toning and tightening that lower belly pooch.

Lie on the floor, on your back. Spread your arms out to the sides of your body and straighten your legs out. Your body should resemble a "T" shape.

Raise your legs off the floor. Bend you knees at a 90-degree angle and pull them into your chest while holding your upper body still. Your hips will slightly lift off the floor as your knees get close to your chest.

Extend you legs back down to the starting position. Keep your legs straight and hovering above the floor. Avoid touching the floor. Repeat the exercise to complete as many repetitions and sets as your fitness level allows.