Weight Loss Surgery: Obesity

Content provided by the Faculty of the Harvard Medical School

Weight-loss surgery

For people with severe obesity, diet and medications may have little effect. In some cases, their best chance for long-term weight reduction and improved health may be surgery to promote weight loss, called bariatric surgery. The long-term results of bariatric surgery are impressive. Even more than a decade after surgery, 90% of those who've undergone gastric bypass, the most common bariatric procedure, manage to keep off an average of 50% of the excess weight. The result is a cure or substantial improvement in diabetes, sleep apnea, degenerative arthritis, and hypertension, and a reduction in risk factors for heart disease, including elevated cholesterol.

Surgeons have been doing bariatric surgery for several decades, but the number of people undergoing the procedure (most of whom are women) has soared — from 36,700 in 2000 to 171,000 in 2005, according to figures from the American Society for Bariatric Surgery. The surge has been influenced not only by the growing number of people with severe obesity, but also by improved surgical techniques and high-profile success stories, such as NBC television weatherman Al Roker's loss of 100 pounds after gastric bypass in 2002.

Like all major operations, bariatric surgery has risks — and severe obesity adds to those risks. Surgical treatment also requires lifelong medical monitoring and major changes in diet and lifestyle. But for most people with severe obesity, the health benefits far outweigh the risks.

Figure 6: Gastric bypass (Roux-en-Y) Roux-en-Y (pronounced roo-en-why) gastric bypass was developed in the late 1960s after surgeons noticed that overweight patients who underwent similar gastric surgery for stomach ulcers lost weight. The upper part of the stomach is converted into a small pouch about the size of an egg. The small intestine is cut and one end is connected to the stomach pouch; the other end is reattached to the small intestine, creating a Y shape. This allows food to bypass most of the stomach and the upper part of the small intestine, although both continue to produce the gastric juices, enzymes, and other secretions needed for digestion. These drain into the intestine and mix with food at the crook of the Y. Advantages: Patients lose weight rapidly for up to two years after surgery. Many maintain a loss of 60%–70% of excess weight for 10 years or more. Gastric bypass is more effective in curing or improving obesity-related health problems than banding procedures. About 80% of people with type 2 diabetes who undergo the procedure are cured. Disadvantages: Gastric bypass is more difficult to perform (whether done as open surgery or laparoscopically) than gastric banding and has a somewhat higher complication rate. It's also associated with a higher risk of vitamin and mineral deficiencies, which may require lifelong supplementation.

National Institutes of Health (NIH) guidelines recommend bariatric surgery only for highly motivated people with a BMI of 40 or more and no success or only temporary success with other approaches to weight loss (see "Are you a candidate for bariatric surgery?"). This therapy may also be appropriate for people with moderate obesity (with BMIs between 35 and 40) if they have an obesity-related health problem, such as type 2 diabetes, heart disease, or sleep apnea. Some experts believe that certain people with milder obesity (BMIs between 30 and 35) might even benefit from this treatment. A 2006 study in the Annals of Internal Medicine compared laparoscopic gastric banding with nonsurgical treatment (which involved a very low-calorie diet, weight-loss drugs, and behavioral change to improve diet and exercise habits) in 80 people with mild obesity. After two years, members of the surgery group had lost nearly 22% of their body weight, compared with 5.5% in the nonsurgical group. And those who had undergone surgery reported a better quality of life.

Only experienced bariatric surgeons should perform the surgery (research suggests it's best to choose one who has performed at least 100 procedures), and patients should receive extensive medical, nutritional, and counseling services before and after surgery.

Bariatric techniques promote weight loss by various mechanisms, not all of them fully understood. Some procedures, such as gastric banding (see Figure 7) restrict food intake by making the stomach smaller, and also change the absorption of some fats and other nutrients. But stomach restriction and preventing nutrient absorption aren't the whole story. Experts believe that obesity surgery also acts through hormonal and neurohormonal pathways that change the body's response to food. People tend to feel fuller and less hungry. With gastric bypass, diabetes may resolve within two weeks of surgery. These changes can't be accounted for just by the weight loss. There are some hormonal changes throughout the body after the surgery that cause you to lose weight and correct the metabolic complications of obesity.

Figure 7: Gastric banding (adjustable) A silicone band about two inches around restricts stomach size to a small upper chamber, with an opening at the bottom to the rest of the stomach and digestive tract. The size of the band can be adjusted by injecting or withdrawing saline through a port implanted just under the skin. The procedure is sometimes called Lap-Band surgery after the brand name of the device used in the U.S. Advantages: Gastric banding surgery is usually done laparoscopically with camera-guided instruments inserted through tiny incisions. Compared with more complicated procedures, such as gastric bypass, it has some advantages. It requires less time in the operating room and a shorter hospital stay. There are fewer post-surgical complications. And the band can be removed if necessary. Disadvantages: Vomiting may occur if food intake is too rapid or the opening into the lower stomach is too narrow. The silicone band may wear, slip, or leak, necessitating another surgery. Compared with gastric bypass, there is generally less weight loss and weight loss is slower. There is less information on its long-term effectiveness.

A lot of research is aimed at finding out why weight-loss surgery is as effective as it is. It's been shown, for example, that levels of ghrelin, a hormone that stimulates appetite, fall after gastric bypass. Scientists have also cured diabetes in animals by simply bypassing the upper part of the intestine (duodenum) — without decreasing the size of the stomach. The body's response to insulin and its production may also change. Learning more about these mechanisms may lead to the development of medications and other strategies that could make surgery unnecessary.

If you are considering bariatric surgery, your primary care provider will refer you to a bariatric surgeon or a center that specializes in bariatric procedures, where you'll be evaluated by clinicians specializing in medicine, nutrition, and psychology. The purpose is to make sure you are physically and mentally prepared for surgery (and the accompanying changes), are willing and able to participate in follow-up care and diet, and understand all the potential risks and benefits.

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Last updated:	June 20, 2007