Bariatric surgery typically takes 1 to 3 hours, depending on the type of procedure performed. Gastric bypass and gastric sleeve surgeries are usually completed within this timeframe. The surgery helps you lose weight by altering your digestive system to limit food intake and reduce calorie absorption. By creating a smaller stomach pouch or rerouting a portion of the digestive tract, bariatric surgery aids in achieving significant weight loss and improving overall health.