People with a body mass index or BMI below 35, on whom the surgery is not typically done, lost weight, says researcher John M. Morton, MD, MPH, associate professor of surgery and director of bariatric surgery and surgical quality at Stanford University.
Their type 2 diabetes also went into remission.
Morton is presenting the study at the annual meeting of the American Society for Metabolic & Bariatric Surgery in Orlando.
His team looked at only 15 people with the lower BMI, including 12 with diabetes.
"I grant you it's a small number," he says. However, putting diabetes in remission sooner rather than later is good, he tells WebMD.
"There is a movement afoot to take a look at [surgery for people with] BMIs of 30 to 35,'' Morton tells WebMD.
National Institutes of Health guidelines recommend gastric bypass surgery be reserved for people with a BMI of 35 or higher with an obesity-related condition such as diabetes, or for people with a BMI of 40 or higher.
However, in February, the FDA approved the Lap-Band weight loss procedure for less obese adults. In the procedure, an inflatable band is placed around the upper part of the stomach. It can now be used in people with a BMI of 30 or higher with at least one obesity-related condition.
In Morton's study, all patients had another type of procedure, the Roux-en-Y surgery, a type of gastric bypass surgery that makes the stomach smaller and allows food to bypass part of the small intestine.
About 220,000 bariatric surgeries are done each year in the U.S, as estimated by the American Society for Metabolic & Bariatric Surgery. The cost ranges from $11,500 to $26,000.
Morton and his colleagues focused on 15 patients whose BMI had fallen below 35 while they were awaiting bariatric surgery.
Most had a BMI of about 34, Morton says. A person 5'10" who weighs 240 pounds has a BMI of 34.4.
The researchers compared the group with the lowest BMIs to 965 others whose BMIs were higher, ranging from 35 to 40, 40 to 50, and above 50.
The average age of the groups ranged from 43 to 51.
Those in group 1, with the lowest BMI, lost a greater percentage of excess weight at the one-year mark, shedding 167% of excess weight. Those in group 2 lost lost 112%, group 3, 85.3%, and group 4, 67.1%.There were no complications in group 1, Morton says.
Everyone in group 1 who had diabetes went into remission, and 72.7% to 74.6% of the others did.
''Bariatric surgery has become a lot safer," Morton says. "We wanted to look at it from the standpoint of outcome. In this new BMI group, the surgery can be done safely with superior results."
There were no complications in the low-BMI group, he says.
Bariatric surgery carries risks, such as vitamin and mineral deficiencies, gallstones, and death. The risk of death from bariatric surgery is about 0.1%, according to the American Society for Metabolic & Bariatric Surgery, citing research and government figures.
Bariatric Surgery: Perspective
Lowering the bar on bariatric surgery is not embraced by everyone. "I don't believe it is appropriate for people who are below a BMI of 35," says Jenn Berman, PsyD, a Beverly Hills, Calif., marriage and family therapist. She counsels patients with eating disorders and people who have had the surgery.
She has seen some patients ''out-eat'' the surgery, eating too much and undoing the benefits.
Eating disorders such as bulimia have to be addressed before the surgery, she says. "I believe that bariatric surgery is appropriate for people who are morbidly obese who have tried absolutely everything else and have been through extensive psychological screening to rule out eating disorders," she says.
However, Bruce Wolfe, MD, president of the American Society for Bariatric & Metabolic Surgery, takes another view. "What was remarkable in this trial was that the induction of remission of the diabetes was complete in all those [with the lowest BMI]," he says.
The study adds some valuable information about the surgery for a group that experts know little about, says Wolfe, a professor of surgery at Oregon Health & Science University in Portland.
This study was presented at a medical conference. The findings should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.