Roux-en-Y gastric bypass reduces the capacity of the stomach by creating a much smaller stomach pouch. The procedure also slows the speed with which food leaves the stomach. It is one of the most frequently performed weight loss procedures in the U.S.
One year after surgery, weight loss can average 70 percent of excess body weight. After 10 to 14 years, some patients have maintained 50 to 60 percent of their excess weight loss.