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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.

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.

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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After surgery

For the first few months after surgery, your appetite will decrease dramatically and you'll eat substantially less food. If you eat too quickly or too much, your stomach pouch can overfill, and you may vomit or feel pain in the chest and upper abdomen. You may need to take supplementary vitamins (especially vitamins B₁₂ and D) and minerals (especially calcium and iron). After about a year, most people increase their food intake to 1,200 calories per day. You will need to be closely monitored by a physician, who can help address the common complications of bariatric surgery, such as gallstones, kidney stones, and ulcers. Some people develop other complications, such as a hernia at the incision site, or stenosis — narrowing where the stomach is attached to the small intestine. After a high-carbohydrate meal, a person who has had gastric bypass surgery may suffer from "dumping syndrome," a reaction that causes flushing, sweating, severe fatigue, nausea, vomiting, diarrhea, and intestinal gas. People who lose 100 pounds or more sometimes need additional surgery to remove sagging skin that won't return to normal.

Insurance coverage for bariatric surgery is variable but generally improving. In February 2006, Medicare announced that it will cover most bariatric procedures, including gastric banding and Roux-en-Y gastric bypass, in appropriate patients who are treated at centers endorsed by the American College of Surgeons or the American Society for Bariatric Surgery. This decision may open the door to expanded coverage of other weight-loss treatments as well.

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Other weight-loss therapies

Researchers have experimented with novel solutions that go beyond medication and surgery. Two such potential solutions for treating obesity are special devices that help prevent overeating. One is a pacemaker-like device that delivers low-level electric stimulation to the stomach; the other is a silicone stomach balloon filled with salt water. Although both have been tested and are used in other countries, neither has been approved by the FDA for use in the United States (as of 2006). Experts think these devices probably won't prove very effective alone, but may be useful for certain people in combination with other therapies.

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Gastric stimulator

Known as the gastric electrical stimulator (GES), this matchbox-sized device is implanted under the skin of the abdomen during an hour-long outpatient procedure. An external programming device communicates with the battery-powered implant, triggering it to emit mild electrical shocks. These low-level electrical impulses apparently cause the stomach to relax and distend. This triggers nerves in the stomach to tell the brain that the stomach is full, which is thought to help curb excessive eating. More than 300 people have participated in trials of the device, but these trials have failed to show that the device helps people lose significantly more weight than people in control groups.

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Stomach balloon

The intragastric balloon system consists of a soft silicone balloon that partially fills the stomach, supposedly creating a sense of fullness that then limits eating. The patient swallows the deflated balloon, with the help of numbing drugs on the throat and muscle relaxants. Once the balloon is inside the stomach, the doctor fills it with salt water (saline) through an attached catheter that's immediately removed. The balloon self-seals and then floats freely in the stomach. The balloon needs to be removed after six months, because acid in the stomach may cause the balloon to weaken and deflate.

Although the current intragastric balloon appears to be safer than those tried in the 1980s, it can lead to severe complications. The balloon may deflate before it's supposed to be removed. The empty balloon may pass through the bowel and out of the body, but it's possible that it may become trapped in the bowel, causing an obstruction. If this happens, the balloon may need to be surgically removed; otherwise, the blockage can be fatal. Other side effects can include nausea and vomiting for a few days or longer after placement. Finally, controlled studies have not shown the balloon to be effective for long-term weight loss.

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Review Date: 2006-09-01

Harvard Medical School does not endorse products or services.