Types of Gastric Bypass Surgery and Eligibility

Gastric Bypass Surgery Is One Type of Weight Loss Surgery. Martin J Cook/Moment/Getty Images

There are many treatments for obesity, beginning with lifestyle changes (including diet and exercise) and progressing to medications and surgical operations. One such operation is gastric bypass surgery.

What Is Gastric Bypass Surgery?

Gastric bypass surgery is a type of weight loss surgery, also known as bariatric surgery. It helps patients lose weight by surgically shrinking the size of the stomach—thus causing one to feel full on less food.

There are several forms of gastric bypass surgery, including the Roux-en-Y gastric bypass (RGB) procedure, and biliopancreatic diversion with duodenal switch (also known as extensive gastric bypass). The Roux (pronounced “roo”)-en-Y is the most common gastric bypass operation performed in the United States. All gastric bypass operations are performed under general anesthesia.

Roux-en-Y Gastric Bypass (RGB)

The RGB procedure entails creating a small stomach pouch to limit food intake—one way in which this can be accomplished is by stapling part of the stomach together. This stomach pouch thus becomes the only way for the stomach to receive food. Then a Y-shaped segment of the small intestine is attached to the small stomach pouch. This allows food to bypass parts of the small intestine known as the duodenum and the first section of the jejunum.

It is now possible for this procedure to be done laparoscopically in patients who are appropriate candidates for laparoscopy.

One important consequence of the RGB procedure is that, because the duodenum has been bypassed (and the duodenum is crucial for the absorption of certain vitamins and nutrients), patients who have had the RGB will need careful supplementation of select vitamins and nutrients, and will need to be followed closely for vitamin and nutritional deficiencies.

Biliopancreatic Diversion With Duodenal Switch (BPD/DS)

In this gastric bypass operation, the surgeon creates a small stomach pouch (just as in the first part of the Roux-en-Y procedure described above) by removing a portion of the stomach. Then, in the second part of the operation, a large portion (roughly three-fourths) of the small intestine is bypassed.

The BPD/DS procedure thus limits food intake through the smaller stomach pouch, and then, because of the small intestine being bypassed, it reduces the absorption of calories and nutrients, especially protein and fat. For these reasons, it can result in rapid weight loss, and is considered by many experts to be the most effective bariatric surgery in terms of treating diabetes in those who are also morbidly obese. However, for the same reasons, individuals who have had this operation are at risk for vitamin and nutrient deficiencies and require appropriate supplementation and close follow-up by a specialist.

Who Is a Candidate for Bariatric Surgery?

According to the latest obesity guidelines released by the American Heart Association (AHA), the American College of Cardiology (ACC), and The Obesity Society (TOS), bariatric surgery may be an option for adult patients who meet certain criteria.

These criteria include a body mass index (BMI) of 40 or greater, or a BMI of 35 or greater in a patient who has other medical conditions (known as “comorbid conditions”) caused by obesity. The obesity guideline writing committee did not find sufficient evidence to recommend bariatric surgery for patients who have BMIs that fall below these cutpoints.

The guideline further advises primary care doctors and others caring for patients with obesity with high BMI to try “behavioral treatment with or without pharmacotherapy” first, and then if this has not worked along with other diet and lifestyle measures to achieve sufficient weight loss, bariatric surgery may be considered.


Bariatric surgery procedures. American Society of Metabolic and Bariatric Surgery. Accessed online at http://asmbs.org/patients/bariatric-surgery-procedures#bpd on July 28, 2014.

Jensen MD, Ryan DH, Apovian CM, et al. 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and The Obesity Society [published online November 27, 2013]. J Am Coll Cardiol.

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