Biliopancreatic Diversion and Biliopancreatic Diversion With Duodenal Switch

Surgery Overview

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 for people who are more than severely obese and who haven't been able to lose weight any other way. Super 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 super 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.
  • In a biliopancreatic diversion with duodenal switch, a different part of the stomach is removed and the surgeon leaves the pylorus intact. The pylorus is the valve that controls food drainage from the stomach. This surgery is high-risk and 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).

What To Expect After Surgery

You will have some belly pain and may need pain medicine for the first week or so after surgery. The cut that the doctor makes (incision) may be tender and sore. Because the surgery makes your stomach smaller, you will get full more quickly when you eat. Food also may empty into the small intestine too quickly. This is called dumping syndrome. It can cause diarrhea and make you feel faint, shaky, and nauseated. It also can make it hard for your body to get enough nutrition. Having a duodenal switch reduces the risk of dumping syndrome.

Depending on how the surgery was done (open or laparoscopic), you'll have to watch your activity during recovery. If you had open surgery, avoid heavy lifting or strenuous exercise while you are recovering so that your belly can heal. In this case, you will probably be able to return to work or your normal routine in 4 to 6 weeks.

Eating after surgery

Your doctor will give you specific instructions about what to eat after the surgery. For about the first month after surgery, your stomach can only handle small amounts of soft foods and liquids while you are healing. It is important to try to sip water throughout the day to avoid becoming dehydrated. You may notice that your bowel movements are not regular right after your surgery. This is common. Try to avoid constipation and straining with bowel movements.

Bit by bit, you will be able to add solid foods back into your diet. You must be careful to chew food well and to stop eating when you feel full. This can take some getting used to, because you will feel full after eating much less food than you are used to eating. If you do not chew your food well or do not stop eating soon enough, you may feel discomfort or nausea and may sometimes vomit. If you drink a lot of high calorie liquid such as soda or fruit juice, you may not lose weight. If you continually overeat, your stomach may stretch. If your stomach stretches, you will not benefit from your surgery.

This surgery removes the part of the intestine where many minerals and vitamins are most easily absorbed. Because of this, you may have a deficiency in iron, calcium, magnesium, or vitamins. It's important to make sure you get enough nutrients in your daily meals to prevent vitamin and mineral deficiencies. You may need to work with a dietitian to plan meals. And you may need to take extra vitamin B12.

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.

Most surgeons will not perform duodenal switch surgery unless you are super obese (body mass index (BMI) of 50 or higher) and your weight is causing serious health problems.

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.footnote 1 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.footnote 2


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.footnote 3



  1. Colquitt JL, et al. (2009) Surgery for Obesity. Cochrane Database of Systematic Reviews (2).
  2. Heber D, et al. (2010). Endocrine and nutritional management of the post-bariatric surgery patient: An Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology and Metabolism, 95(11): 4823–4843. Available online:
  3. Adams TD, et al. (2007). Long-term mortality after gastric bypass surgery. New England Journal of Medicine, 357(8): 753–761.


Current as of: September 23, 2020

Author: Healthwise Staff
Medical Review:
E. Gregory Thompson MD - Internal Medicine
Kathleen Romito MD - Family Medicine
Martin J. Gabica MD - Family Medicine
Ali Tavakkoli FACS, FRCS, MD - General Surgery, Bariatric Surgery

Biliopancreatic Diversion and Biliopancreatic Diversion With Duodenal Switch