Gastric bypass, commonly known as Roux-en-Y (roo-en-wy) Gastric Bypass, is a kind of weight-loss surgery that entails separating a small pouch from the stomach and attaching the newly formed pouch straight to the small intestine. Following a gastric bypass, eaten food will travel through this little pouch of the stomach and into the small intestine, skipping most of the stomach and the first ...