Introduction to Gastric Bypass Surgery Gastric bypass surgery is often considered the gold standard in weight loss surgery. It’s been the procedure by which all newer weight loss surgeries are compared. There are different variations of the gastric bypass, but they all share a common structure. The procedure creates a small rectangular gastric pouch, roughly 20-30ml in volume, made from the upper stomach. The small intestine is then connected to this pouch, and ingested food bypasses the stomach and the duodenum, starting digestion further down the small intestine. In practice, there are two primary types of gastric bypass: Roux-en-Y gastric bypass, first performed in 1967, and One anastomosis gastric bypass (also known as mini gastric bypass or loop gastric bypass). Additionally, the procedure can be tailored to individual patients by adjusting the length of the bypassed intestine or placing a ring around the pouch to prevent stretching. While this customization may lead to better weight loss or better management of metabolic conditions like diabetes, it also introduces potential risks like malnutrition and diarrhoea. Both types of gastric bypass are generally performed via laparoscopic (keyhole) surgery, requiring only one or two nights in the hospital. How Does Gastric Bypass Surgery Work?