For people who have a lot of weight to lose, weight-loss surgery appears more effective than diet and exercise, a new review suggests.
The one caveat to this study, however, is that the results only include two years of data, so the long-term outcomes are still unknown. This type of study, called a meta-analysis, attempts to uncover a common thread in a number of previous studies.
"Individuals allocated to bariatric surgery lost more body weight on average – 26 kilograms [57.3 pounds] – compared with nonsurgical treatment, and had higher remission rates of type 2 diabetes and metabolic syndrome," said study author Viktoria Gloy, a scientist at the Basel Institute for Clinical Epidemiology and Biostatistics at University Hospital Basel in Switzerland. Metabolic syndrome is a group of symptoms that increase the risk for type 2 diabetes and heart disease.
"After surgery, patients also reported greater improvements in quality-of-life measures, and had greater reduction in medication use than nonsurgical patients," Gloy added.
Gloy and colleagues published the findings online in the BMJ.
Significant public health risk
Obesity is a significant public health risk, according to background information in the report. The incidence of obesity has more than doubled over the past 25 years in the United States, the United Kingdom and in Australia. More than two-thirds of the US population are currently overweight or obese. Many European countries aren't far behind, with overweight and obesity rates of around 40% to 50%, according to researchers.
Obesity increases the risk of many serious ailments, including type 2 diabetes, high blood pressure, high cholesterol, cardiovascular disease, some types of cancer and musculoskeletal diseases such as osteoarthritis, according to the analysis.
Treatments for obesity include weight-loss surgery and nonsurgical options, such as changes in diet, medications, and increasing physical activity.
To see what treatments help people lose weight and improve their health the most, Gloy and her colleagues reviewed previously completed studies on weight loss, and found 11 studies with nearly 800 people who'd undergone weight-loss surgery or nonsurgical weight-loss treatments.
In addition to losing more weight, those who had weight-loss surgery had a rate of remission of type 2 diabetes that was 22 times higher than in the group that did not get surgery. Rates of metabolic syndrome also dropped more for those who had surgery, according to the analysis.
Triglycerides, a type of blood fat, dropped more, and levels of the good cholesterol (HDL) increased more for those who had surgery.
There were no significant differences in blood pressure levels and bad cholesterol (LDL) levels between the two groups, the investigators found.
"The evidence beyond two years of follow-up, in particular adverse events, cardiovascular diseases and mortality, remains unclear and calls for further research on the topic," noted Gloy.
Remission of type 2 diabetes
Dr Joel Zonszein, director of the clinical diabetes center at Montefiore Medical Center in New York City, said: "Weight gain is very easy, but to lose weight is very difficult. This was a careful meta-analysis, and I agree with what they've found. We don't yet understand exactly how bariatric surgeries cause remission of type 2 diabetes," he pointed out.
Another expert said weight-loss surgery should be happening more often.
"Bariatric surgery is underutilised. If we were talking about any other treatment with such a striking effect on diabetes, it would be offered to patients sooner," said Dr Mitchell Roslin, chief of obesity surgery at Lenox Hill Hospital in New York City.
Of course, like any surgery, weight-loss surgeries don't come without risk. The most common complications reported in the current analysis were iron deficiency anemia and the need for re-operation. The surgery is also expensive. The US National Institute of Diabetes and Digestive and Kidney Diseases estimates that weight-loss surgery averages as much as $25,000.
Roslin and Zonszein both said that people undergoing weight-loss surgery need to be carefully chosen. Current recommendations recommend the surgery for anyone with a body mass index (BMI) above 40, or a BMI of 35 or higher if they have other conditions related to obesity, such as type 2 diabetes or high blood pressure. BMI is a measurement based on height and weight.
Other metabolic abnormalities
But, both experts felt that more people should be included in those recommendations. Zonszein said people with BMIs as low as 30, if they had evidence of other metabolic abnormalities, should be counseled on the surgery. Roslin also said that if people with type 2 diabetes can't maintain control on oral medications that they should be offered a surgical option.
Roslin said that people with type 2 diabetes should try to lose weight and exercise more first. "Give yourself a chance to make lifestyle changes. But, it's very hard to lose 5% of your body weight. If you don't think you'll be able to do it, then you owe it to yourself to learn about surgical options," he suggested.
"There are real risks with surgery that shouldn't be underestimated, but there are real risks from diabetes, too," Roslin noted. "Let's say we were talking about colon cancer instead of diabetes, and I said, 'There's a treatment that could reduce your risk by 22 times, but it's invasive, would you consider it?'"
Learn more about the different types of bariatric surgery from the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.