Dr. Christopher P. Menzel, MD

During gastric bypass surgery, the stomach is stapled to reduce its size, and a small hole is created in the stomach and attached to the middle section of the small intestine. This direct connection between the stomach and the middle of the small intestine creates a channel for some food to bypass the normal route. By bypassing the upper small intestine and larger region of the stomach, food is not fully absorbed and patients do not retain the same amount of calories as before. This procedure is also sometimes referred to as "Roux-en-Y" gastric bypass surgery. Some bariatric surgeons may perform a "laparoscopic bypass" which uses a tiny camera (laparoscope) to guide the procedure.

Gastric bypass surgery is performed with general anesthesia and as preparation, a liquid diet is required for two weeks prior to undergoing the surgery. After the surgery, patients will spend about two days in the hospital and may miss work for two to three weeks. In the first month after the surgery, patients are only able to consume small portions of liquid or soft food. Even after reintroducing solid food, patients feel full quickly, sometimes after eating just two or three tablespoons. Some patients experience "dumping syndrome" (rapid processing of food into the small intestine), which is common during the recovery process. Gastric bypass surgery patients must also make permanent lifestyle changes. For example, gastric bypass patients are required to take vitamins for life after surgery and required to forever avoid certain foods, such as alcohol, sugar, and high fat food.

While the gastric bypass recovery process can be challenging, surgery results are usually swift: most gastric bypass surgery patients lose nearly half to two thirds of their starting weight within two years of surgery.

By far the most common of the gastric bypass surgeries is called Roux-en-Y. During this surgery, part of the stomach and small intestine are detached from the gastrointestinal tract, in order to make the tract smaller. The surgeon divides the stomach into two parts. The working stomach, at the end of the esophagus, is now tiny - only the size of a walnut. This makes patients feel full after eating a small amount of food. Then the small intestine is also divided, and after bypassing a section of the small intestine to reduce food absorption, the intestine is attached to the small stomach pouch. The patient now has a working stomach and intestine like before, only much smaller.

Because gastric bypass is used to treat extreme obesity, it can reduce the risk of some of the problems associated with obesity. Gastric bypass can help treat or reduce the risk for such conditions as heart disease, high blood pressure, sleep apnea, and type 2 diabetes. However, it is a major surgery and also carries risks itself. Any surgery can lead to infection, bleeding, or blood clots, and weight loss surgery in particular carries risks of leaks in the gastrointestinal system, malnutrition, bowel obstructions, and vomiting.

Typically patients are considered candidates for gastric bypass surgery if they have a BMI greater than 40, or sometimes if they have a BMI between 35 and 40 but are suffering from obesity-related illnesses such as diabetes. The outlook is generally good, with most patients losing between 50-75% of their excess weight in 1-2 years. However, patients must follow strict diet guidelines so that the stomach can heal, starting with no food at all, then followed by a liquid diet for some time. For many severely obese patients who have tried strict diets before without success, gastric bypass surgery is the tool that allows them to finally achieve their weight loss and health goals.