Gastric bypass, also known as Roux-en-Y (roo-en-wy) gastric bypass, is a type of weight-loss surgery. This procedure involves creating a small pouch from the stomach and connecting this newly created pouch directly to the small intestine, bypassing a large part of the stomach and the initial segment of the small intestine. This alteration reduces the amount of food the stomach can hold and decreases nutrient absorption, aiding in significant weight loss.