Surgery that makes the stomach smaller and allows food to bypass part of the small intestine, with the goal of promoting weight loss. Gastric bypass surgery is typically considered only in extremely obese individuals (those with a body-mass index [BMI] of 40 or more), or in those with a BMI of 35 to 40 who have life-threatening or debilitating conditions related to their weight, such as high blood pressure, coronary artery disease, obstructive sleep apnea, asthma, or osteoarthritis. This surgery is considered only after other therapies, including diet, exercise, behavior therapy, and medicines, have failed to produce adequate weight loss.
In the most common form of gastric bypass surgery, called Roux-en-Y gastric bypass, surgeons use surgical staples or a plastic band to create a small pouch at the top of the stomach, making it smaller. They then connect the stomach directly to the middle of the small intestine, bypassing the rest of the stomach and the upper part of the small intestine. The bypass can be done as an “open” procedure, through a large incision in the abdomen, or laparoscopically, using small instruments viewed through a tiny camera, all inserted through small incisions. The open procedure usually requires a hospital stay of 4–6 days, while the laparoscopic procedure requires only a 2- to 3-day hospital stay.
Since the stomach is made smaller by the surgery, people feel full more quickly, so they consume less food. Also, since food bypasses part of the small intestine, fewer calories are absorbed. Both of these effects promote weight loss.
As part of a regimen that includes regular physical activity and a nutritious meal plan, gastric bypass surgery effectively causes profound long-term weight loss. In people with Type 2 diabetes, the procedure can normalize blood glucose levels and insulin levels. The surgery also appears to improve other associated conditions, such as high blood pressure, heartburn, obstructive sleep apnea, high cholesterol levels, or osteoarthritis.
The surgery is not without risks or side effects. It can cause dumping syndrome, in which food moves too quickly through the stomach and intestines, causing such distressing symptoms as nausea, palpitations, diarrhea, abdominal pain, and light-headedness. The problem most commonly occurs after a person eats foods high in refined carbohydrate.
Other potential complications include gastrointestinal leakage into the abdominal cavity, pulmonary embolism (a blood clot in the lungs), gallstones, an infection in the surgical incision, and nutrient deficiencies.