Gastric bypass surgery involves dividing the stomach into two parts: a small upper pouch and a larger lower section. The small intestine is then attached to the small pouch, allowing food to bypass most of the stomach and the first part of the small intestine. This alters how the body absorbs calories from food, promoting significant weight loss. The surgery is generally only considered for those who cannot lose weight through diet and exercise alone. It can help patients lose up to 77% of excess weight and may resolve or decrease health issues like diabetes and some cancers. However, lifelong changes to diet and lifestyle are needed to maintain the results, and there are risks of complications from the surgery.