NEW YORK - At six-year patient follow-ups, three quarters of people who'd undergone gastric bypass surgery had lost at least 20 per cent of their pre-surgery weight and kept it off, researchers found.
"It's been somewhat in question how durable the weight loss might be," said lead author Ted Adams, from the University of Utah School of Medicine in Salt Lake City.
"What's unique to this study is that it's demonstrating that long term, out six years, there's still a really significant remission of diabetes" and most of the initial weight people lose stays off.
According to the American Society for Metabolic and Bariatric Surgery, about 200,000 people have weight loss surgery every year. The procedures run about US$20,000 (S$24,517) each.
Bariatric surgery is typically recommended for people with a body mass index (BMI) - a measure of weight in relation to height - of at least 40, or at least 35 if they also have co-occurring health problems such as diabetes or severe sleep apnea.
That's the equivalent of a six-foot person who weighs 295 pounds or more, or a five-foot, six-inch person who's at least 217 pounds with other weight-related health issues.
During a gastric bypass, the most common type of weight loss surgery, a surgeon shrinks the stomach by making its upper portion into a walnut-sized pouch and connecting that directly to the small intestine.
The new study included 418 severely obese people who had the procedure beginning in 2000.
The researchers compared those patients to another 417 people who sought weight loss surgery but didn't end up going through with it and 321 who were also obese but didn't seek out surgery.
Six years later, gastric bypass patients had lost and kept off more than one quarter of their initial weight, on average. Sixty-two per cent of patients who were originally diabetic no longer had the blood sugar disorder, and 42 per cent had their high blood pressure return to normal.
Participants in the comparison, no-surgery groups didn't lose any weight - and more of them developed diabetes than had improvements in blood sugar control, according to findings published Tuesday in the Journal of the American Medical Association.
Complications linked to gastric bypass include infections and nutrient deficiencies, and some people need a second operation in the months afterward.
"Both in the short and the long term, there are complications and consequences to consider, but that in my opinion… does not (trump) the health benefits," said Dr. Anita Courcoulas, a bariatric surgeon from the University of Pittsburgh Medical Center who wrote a commentary accompanying the new research.
In an Australian study published concurrently, obese people who'd undergone another type of bariatric surgery didn't see their sleep apnea symptoms improve any more than obese people assigned to a conventional weight loss therapy group.
And few people had their sleep apnea - a condition that's much more common in obese people - disappear altogether.
That points to the need for closer monitoring of sleep problems after bariatric surgery, Courcoulas told Reuters Health. Even if symptoms have abated, people who still have sleep apnea need to be using breathing devices at night, she said.
Courcoulas added that taken together, the new studies can help inform people considering weight loss surgery about what to expect down the line.
"It's a major surgery and there are always risks to surgery," Adams told Reuters Health. What's more, "this procedure naturally results in a major lifestyle change in terms of diet and a host of other factors."
Those concerns have to be discussed before surgery, along with the possible benefits, he said.
"This study adds additional information for the doctor and the patient to consider as part of that equation, whether or not they should have surgery," Adams concluded.