Roux-en-Y gastric bypass surgery is one of the most common weight loss surgeries, accounting for about 47% of all weight loss surgeries. The procedure has two parts:

Part One: Making a Small Pouch in the Stomach

The surgeon divides the stomach into a large portion and a much smaller one. Then, in a process sometimes called “stomach stapling,” the small part of the stomach is sewn or stapled together to make a pouch, which can hold only a cup or so of food.

With such a small stomach, people feel full quickly and eat less. This strategy is also called “restrictive,” because the new stomach size restricts how much food it can hold.

Part Two: Bypass

The surgeon disconnects the new, small stomach pouch from the majority of the stomach and first part of the small intestine (the duodenum), and then connects it to a part of the small intestine slightly farther down (the jejunum). This surgical technique is called a “Roux-en-Y.”

After a Roux-en-Y, food passes directly from the stomach into the jejunum, bypassing the duodenum. This curbs your absorption of calories and nutrients. This weight loss method is called “malabsorptive.”

Stomach stapling and Roux-en-Y are typically done during the same surgery and together are called a “Roux-en-Y gastric bypass.”

Usually, surgeons do both laparoscopically (using tools inserted through small cuts in the belly). When laparoscopy isn’t possible, surgeons may do a laparotomy (involving a large cut in the middle of the belly).