Gastric banding: A silicone ring (sleeve) is placed around the juncture of the esophagus and the stomach. This restricts the amount of food that can fit into the stomach. The surgery takes 30-40 minutes and the patient can leave the hospital within a few hours. Complications are rare (the band can slip, or cause an ulcer). The change takes getting used to, as eating too much will hurt and can induce vomiting. There is a higher than 50 percent chance of keeping off more than half the excess weight five years on. The procedure is reversible. Sleeve gastrectomy: The stomach is reduced to a "sleeve" about 15% of its original size and stapled shut. The surgery takes a little over one hour, and the patient can leave the hospital in three to five days. The procedure is irreversible - but over time the stomach can be stretched out through overeating. Gastric bypass: The most common bariatric surgery, the gastric bypass involves reducing the stomach to about 10% of its original size and channeling food farther own the intestines to speed the feeling of satiety. Duodenal switch: Similar to the gastric bypass, the duodenal switch involves reducing the volume of the stomach (usually to around one-fourth of its size) and bypassing a section of the intestines to reduce absorption of food. The combination is highly effective for weight loss - but it requires the patient to take vitamin and mineral supplements.