Upper and lower abdomen fat and loose skin are due to heredity, aging, pregnancy and massive weight loss. This is a common area of fat deposition in obesity, especially in men. Pregnancy and weight loss can produce stretched-out abdominal skin that sags. The ideal initial approach is to lose weight and strengthen the abdominal muscles. Most cases can be treated by laser liposuction under local anesthesia that can remove the unwanted fat and tighten the skin. Advanced cases of sagging, loose skin may require tummy tuck (abdominoplasty). Stretch marks or striae, are due to the tearing and scarring of the dermis, the lower layer of skin. Stretch marks are common during puberty and rapid growth spurts in adolescence (they typically heal by the late teens or early 20s), pregnancy, excessive weight gain and obesity.