Weight-loss surgery more effective than diet and exercise for obese patients

Bariatric surgery is more effective than non-surgical options at reducing body weight and increasing remission rate of type 2 diabetes, suggests an analysis of the available randomised controlled trials, published on bmj.com.

However, the evidence beyond two years remains unclear and calls for further research on the topic, say the authors.

Obesity is one of the greatest public health problems in industrialised countries. Currently, 67% of the US population is either overweight or obese, and in most European countries, levels are between 40 and 50%.

Bariatric surgery may be performed on people who are obese for whom all non-surgical weight loss treatments have failed. Current guidelines recommend evaluation of surgery for individuals with a body mass index (BMI) of at least 40 or at least 35 if accompanied by other serious diseases related to obesity.

Procedures can include reducing the size of the stomach with a surgical band (gastric banding), re-routing the small intestines to a small stomach pouch (gastric bypass), or removing a portion of the stomach (sleeve gastrectomy). But the effects of surgery compared with non-surgical treatments remain unclear.

So a team of international researchers analysed the results of 11 randomised controlled trials involving 796 obese individuals (average BMI ranged from 30 to 52).

Individuals allocated to bariatric surgery lost more body weight (on average 26 kg) compared with non-surgical treatment, and had higher remission rates of type 2 diabetes and metabolic syndrome (a cluster of conditions that increase the risk of developing heart diseases and diabetes).

After surgery, patients also reported greater improvements in quality of life measures – and had greater reductions in medication use than non-surgical patients.

Blood lipid profile improved more after bariatric surgery. Blood pressure was not significantly different between the two groups.

There were no cardiovascular events or deaths reported after bariatric surgery. The most common adverse events after surgery were iron deficiency anaemia and re-operations.

“This meta-analysis provides comprehensive evidence that, compared with non-surgical treatment of obesity, bariatric surgery leads to greater body weight loss and higher remission rates of type 2 diabetes and metabolic syndrome,” say the authors.

However, they stress that results are limited to two years’ follow-up and based on a small number of studies and individuals.

“The evidence beyond two years of follow-up, in particular on adverse events, cardiovascular diseases, and mortality remains unclear and calls for further research on the topic,” they conclude.