This article originally appeared in the March 2004 Harvard Health Letter and is provided courtesy of Harvard Health Publications.

Obesity in the extreme

It has risks, but surgery is the most effective treatment for people with severe obesity

The epidemic of obesity in the United States has been amply documented and duly decried. But as fast as the number of bigger Americans is growing, the population of those with severe obesity is growing even faster, according to a study published last year by Roland Sturm, a Rand Corporation researcher.

Analyzing the results of a large government telephone survey that is often used to track health trends, Sturm found that the number of Americans with obesity — which means having a body mass index (BMI) of 30 or more — roughly doubled between 1986 and 2000. During the same period, the number with severe obesity (a BMI of 40 or more) quadrupled, and those with a BMI of 50 or more increased over five times.

Your BMI depends on your weight and your height, but for most people a BMI of 40 means being about 100 pounds overweight (see chart below). By Sturm’s calculations, 1 in every 50 Americans — or about 5.8 million people — has a BMI of 40 or more, and 1 in every 400 — or about 730,000 people — has a BMI of 50 or more.

Consequences and causes
Extreme obesity is sometimes called morbid obesity, although doctors who treat the condition discourage use of the term, saying that it’s both misleading and has negative connotations. Indeed, specialists speak of their patients having obesity and avoid the label obese patients.

The study that is still most frequently cited to illustrate the serious consequences of extreme obesity was published over 20 years ago in the Journal of the American Medical Association. It included 200 men whose average weight was 316 pounds. A quarter of the men died during the 7H years that researchers kept tabs on them, a mortality rate many times higher than the average population.

Obesity is associated with a range of health problems, from diabetes to back problems to several types of cancer. In nearly all cases, extreme obesity makes these problems even more likely, although by how much varies from condition to condition. And sometimes extreme obesity seems to create its own troubles. For example, a recent study found a strong connection between extreme obesity and depression, but not with regular obesity.

Sturm argues that the growing number of the extremely obese suggests that it isn’t primarily a genetic phenomenon afflicting a relatively fixed number of people, but part of the larger shift of Americans to the heavier end of the scale. Yet research has also shown a strong genetic influence, and over 200 obesity-related genes have been identified, although their particular role in producing the disease hasn’t been fully worked out.

Diet and drugs
People with obesity can lose weight by dieting. Adding exercise to calorie cutbacks (the essence of any diet) doesn’t aid the immediate weight loss from calorie restriction, but does appear to improve the odds of keeping pounds off over the long term. Still, success for most dieters is fleeting. Research shows that after five years, fewer than 5% maintain a 10% decrease in weight.

The FDA has approved two drugs for obesity that can be taken for a year. Orlistat (Xenical) blocks fat absorption by the gut. Sibutramine (Meridia) suppresses appetite. In studies, they’ve been shown to help some people lose about a tenth of their initial body weight. Are these medications effective in people with extreme obesity? Dr. Susan Yanovski, a National Institutes of Health expert on obesity drugs, told the Health Letter that she didn’t know of any studies that answered that question directly. In fact, she said many of the obesity drug studies have specifically excluded those who are extremely obese. On the other hand, Yanovski said she didn’t know of any reason why they wouldn’t be effective for very heavy people.

Surgery
Surgery to reduce weight is called bariatric surgery. Surgeons have been doing bariatric operations for over 50 years, but the number of patients has soared recently. About 100,000 operations were performed last year, double the number performed three years ago. The fact that most of the operations can be done laparoscopically through small incisions has helped fuel the popularity.

The risks of these operations are making news, especially in Boston, where two patients at Harvard-affiliated hospitals have died after obesity surgery in the past several months. In most studies, the mortality rate for obesity surgery is under 1%. That compares favorably to the rate for, say, coronary artery bypass surgery, which hovers around 2%. But isn’t bariatric surgery elective? The immediate medical necessity may not be as clear-cut as it is for some heart operations and patients, but proponents of bariatric surgery say that not treating severe obesity is also dangerous — and that surgery is by far the most effective therapy. Diet and drugs help a relatively small number of people lose a small amount of weight. Studies of gastric bypass (see sidebar) have shown that the average weight loss more than 10 years after the surgery is about 50% of excess weight, or about 50 pounds for most people with a BMI of 40.

Surgery for extreme obesity is an aggressive treatment of a serious problem. The operations are difficult to perform, especially laparoscopically. Moreover, having obesity is itself a risk for surgical complications. Some doctors say more systematic research is needed to answer questions like which patients benefit most, what is the most effective operation, and whether specialized units need to be established. To that end, the National Institute of Diabetes and Digestive and Kidney Diseases announced last year it would create a clinical research consortium to assemble a large database on bariatric surgery.

Other research is directed at finding out why the operations are effective, because it’s now clear that it isn’t simply a matter of making the stomach smaller or reducing food absorption. It has already been shown, for example, that levels of ghrelin (pronounced GRAY-lin), a hormone that stimulates appetite, fall after gastric bypass surgery. Ghrelin-blockers might be among the next generation of obesity drugs.