Adults with severe obesity had greater initial and sustained weight loss with gastric bypass surgery than either sleeve gastrectomy or adjustable gastric banding, according to a new study published today in the Annals of Internal Medicine.

This is the largest long-term study of bariatric surgery to date. It included more than 46,000 patients at 41 participating health systems in 11 Clinical Data Research Networks nationwide, thanks to its use of a large new resource called PCORnet®, the National Patient-Centered Clinical Research Network.

Bariatric surgeons can use various operations to help people lose weight by making changes to their digestive system. This study did a head-to-head comparison of 1-, 3-, and 5-year results from the three most commonly performed weight loss operations: gastric bypass, sleeve gastrectomy, and adjustable gastric banding.

The findings are important because severe obesity—a BMI of at least 35 kg/m²—affects more than 15% of US adults, according to the National Health and Nutrition Examination Survey. National Institutes of Health guidelines consider people with a BMI of 40 kg/m², or at least 35 kg/m² for people with diabetes or other obesity-related diseases, eligible for bariatric surgery.

“Bariatric surgery is widely considered the most effective way to treat severe obesity and induce long-term weight loss,” said first author David Arterburn, MD, MPH, an internist and senior investigator at Kaiser Permanente Washington Health Research Institute. “We wondered about sleeve gastrectomy, which has quickly become the most commonly performed bariatric procedure in the United States. Because it’s the newest—introduced less than a decade ago—less evidence has been available to compare it against the longstanding gastric bypass and adjustable gastric band.”

The investigators found that:

•People who had gastric bypass surgery had lost 31% of their weight at the first year and maintained 26% of their loss at 5 years.
•People who had sleeve gastrectomy had lost 25% of their pre-surgery body weight at 1 year and maintained 19% weight loss at 5 years.
•That translates into a 19-pound difference in weight loss between gastric bypass and sleeve gastrectomy at 5 years for the average person in this study, who weighed 277 pounds before surgery.
•By contrast, adjustable gastric banding was much less effective for losing weight and keeping it off, with 14% and 12% of weight lost at 1 and 5 years, respectively. Gastric banding used to be the most commonly performed bariatric procedure, but it now represents just 10% of bariatric procedures.

“These findings give strong evidence that bypass and sleeve are effective for lasting weight loss for adults with severe obesity,” said Kathleen M. McTigue, MD, MPH, MS, another study leader and an associate professor of medicine and epidemiology at the University of Pittsburgh. “We hope this helps people to make more informed decisions about their care, as they talk with their health-care providers about the respective benefits and risks of the most common weight loss procedures.”