In a sleeve gastrectomy, also known as vertical sleeve gastrectomy or the gastric sleeve procedure, the outer margin of the stomach is removed to restrict food intake. This leaves a sleeve-shaped stomach, roughly the size and shape of a banana, and retains the pylorus, the muscle that controls the emptying of food from the stomach into the intestine. Sleeve gastrectomy is a purely restrictive procedure. By reducing the size of the stomach, a sleeve gastrectomy allows patients to feel full after eating less and consuming fewer calories. The surgery also removes the portion of the stomach that produces a hormone responsible for inducing hunger. The sleeve gastrectomy is simpler than the gastric bypass procedure because it does not involve rerouting or reconnecting the intestines. Unlike the Lap-band procedure, the sleeve gastrectomy does not require the implantation of a banding device around a portion of the stomach.