The abdominal wall consists of skin, fat, and muscle. The rectus abdominis muscles, which form the “six pack” of muscles on the abdomen, are covered by a firm sheath called the rectus fascia. This fascial layer frequently weakens and stretches out with pregnancy and weight gain. As a result, once a patient loses weight or has her children, she may be left with laxity of the abdominal wall. During a tummy tuck the fascial layer over the rectus abdominis muscles is tightened, and the excess skin and fat are removed.