It's pretty drastic, but surgery can help some people who haven't been able to solve their obesity problem any other way. But people who get bariatric surgery don't just need to lose weight for the sake of losing weight; they're also trying to reduce their risk of an untimely death from diabetes or other obesity-related ills. And weight loss isn't without risk; some studies have suggested that obese people who lose a lot of weight are at a higher risk of dying from cardiovascular disease. Researchers in Sweden followed people who'd had bariatric surgery for up to 10 years to look at the long-term effects.

What the researchers wanted to know: How does bariatric surgery affect risk factors for cardiovascular disease? Do people who've had bariatric surgery eat less and exercise more than obese people who haven't?

What they did: More than 11,000 people applied to the Swedish Obese Subjects study between September 1987 and November 2000. Nearly 7,000 joined the study, and 5,750 are included in this analysis. The study wasn't random; people only got surgery if they wanted it and were eligible. Before the operation, each surgery patient was paired with a control who wasn't going to have surgery but was as close a match as possible on a variety of variables, from smoking status to height to sex. The surgery subjects and their controls came in for examinations six months and a year after surgery, then every year or two for 10 years.

What they found: First of all, surgery did indeed work for weight loss; after 10 years, people who had surgery lost an average of 13 to 25 percent of their body weight, depending on which kind of surgery they had. Controls gained an average of 1.6 percent after 10 years. People who'd had surgery ate less than did controls. They were also more likely to be physically active. That's all pretty much what you expect after bariatric surgery, but this study also looked for the effects of those changes on health. People who'd had surgery were less likely to have diabetes, hypertriglyceridemia, and hyperuricemia than were controls. Surgery didn't have a benefit for hypercholesterolemia. Gastric bypass surgery was better than stomach banding at weight loss and at improving cardiovascular risk factors—possibly because gastric bypass surgery may reduce the "I'm hungry" signals sent from the gut to the brain.

What the study means to you: Bariatric surgery seems to be a good option for people who are dangerously obese. People lost weight and kept it off with the surgery, and they improved some cardiovascular risk factors.

Caveats: The glaring limitation of this study is that people weren't randomly assigned to get bariatric surgery or standard treatment for obesity. The authors say that's because in 1987, when this study was approved, the ethics review boards thought that the risk of dying after bariatric surgery was so high that it was unethical to randomly assign people to have the surgery. (In the 1970s and 1980s, up to 5 percent of people who had the surgery died.) Of the 2,010 people who had surgery, five (0.25 percent) did die after their operations, and 26 had serious enough complications that they had to have more surgery.

Find out more: America's weight problem presents plenty of business opportunities, according to this article from the U.S. News archives: Plumping up profits.

In some situations, adolescents can also be candidates for bariatric surgery.

Information about gastric bypass surgery from the Cleveland Clinic

Read the article: Sjöström, L., et al. "Lifestyle, Diabetes, and Cardiovascular Risk Factors 10 Years After Bariatric Surgery." New England Journal of Medicine. Dec. 23, 2004, Vol. 351, No. 26, pp. 2683–2693.

Abstract online: http://content.nejm.org