Gastric sleeve surgery, also known as sleeve gastrectomy, is a procedure in which a large portion of the stomach is removed, leaving a tube-like structure. This reduces the amount of food that can be eaten and reduces hunger hormones, leading to weight loss. During the procedure, the surgeon will remove about 80% of the stomach, leaving a narrow tube-like structure that is about the size of a banana. The remaining stomach is stapled or sewn together to create the sleeve-shaped stomach. The procedure is typically performed laparoscopically and takes about one to two hours.