A biliopancreatic diversion changes the normal process of digestion by making the stomach smaller. It allows food to bypass part of the small intestine so that you absorb fewer calories. Because of the risks, this surgery is only done in people who are severely obese and who haven’t been able to lose weight any other way. Severe obesity means that you have a BMI (body mass index) of 50 or higher.

After surgery, you will feel full more quickly than when your stomach was its original size. This reduces the amount of food you will want to eat. Bypassing part of the intestine also means that you will absorb fewer calories. This leads to weight loss. But your best chance of keeping weight off after surgery is by adopting healthy habits, such as healthy eating and regular physical activity.

There are two biliopancreatic diversion surgeries: a biliopancreatic diversion and a biliopancreatic diversion with duodenal switch. Most surgeons will not perform duodenal switch surgery unless you are severely obese (BMI of 50 or higher) and your weight is causing serious health problems.

• In a biliopancreatic diversion, part of the stomach is removed. The remaining part of the stomach is connected to the lower portion of the small intestine. This is a high-risk surgery that can cause long-term health problems, because your body has a harder time absorbing food and nutrients. People who have this surgery must take vitamin and mineral supplements for the rest of their lives, which can be expensive. See a picture of a biliopancreatic diversion.
• In a biliopancreatic diversion with duodenal switch, a different part of the stomach is removed, which allows the surgeon to leave the pylorus, the valve that controls food drainage from the stomach, to be left intact. This is a high-risk surgery that can cause long-term health problems, because your body has a harder time absorbing food and nutrients. People who have this surgery must take vitamin and mineral supplements for the rest of their lives, which can be expensive. Another name for this surgery is duodenal switch.

These procedures can be done by making a large cut in the belly (an open procedure) or by making a small cut and using small tools and a camera to guide the surgery (laparoscopy).

Why It Is Done

Weight loss surgery is suitable for people who are severely overweight and who have not been able to lose weight with diet, exercise, or medicine.

Surgery is generally considered when your body mass index (BMI) is 40 or higher. Surgery may also be an option when your BMI is 35 or higher and you have a life-threatening or disabling problem that is related to your weight.

It is important to think of this surgery as a tool to help you lose weight. It is not an instant fix. You will still need to eat a healthy diet and get regular exercise. This will help you reach your weight goal and avoid regaining the weight you lose.

How Well It Works

Biliopancreatic diversion surgeries are effective. Most people lose 75% to 80% of their excess weight (the weight above what is considered healthy) and stay at their new weight. Ten years after weight loss surgery, many people have gained back 20% to 25% of the weight they lost. The long-term success is highest in people who are realistic about how much weight will be lost, keep appointments with the medical team, follow the recommended eating plan, and are physically active.

Risks

Risks common to all surgeries for weight loss include an infection in the incision, a leak from the stomach into the abdominal cavity or where the intestine is connected (resulting in an infection called peritonitis), and a blood clot in the legs (deep vein thrombosis, or DVT) or lung (pulmonary embolism). Some people develop gallstones or a nutritional deficiency condition such as anemia or osteoporosis.

Biliopancreatic diversion surgery has short-term and long-term risks, including:

• Dumping syndrome. This causes nausea, weakness, sweating, faintness, and possibly diarrhea soon after eating. These symptoms get worse if you eat highly refined, high-calorie foods (like sweets). Sometimes you may become so weak that you have to lie down until the symptoms pass.
• A higher risk of osteoporosis. This happens because your body can’t absorb nutrients as well as it used to.
• Bad smelling stools and diarrhea. This can occur because of poor absorption of protein, fat, calcium, iron, and vitamins B12, A, D, E, and K.
• Poor nutrition. Eating less and less absorption may mean that you are not getting enough nutrients, which can cause health problems. You will have to take vitamin supplements for the rest of your life.

What To Think About

Weight loss surgery does not remove fatty tissue. It is not cosmetic surgery.

Some studies show that people who have weight-loss surgery are less likely to die from heart problems, diabetes, or cancer compared to obese people who did not have the surgery.