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