Bariatric surgery (or weight loss surgery) includes a variety of procedures performed on people who are obese. Long term weight loss through standard of care procedures (Roux en-Y bypass, sleeve gastrectomy, and biliopancreatic diversion with duodenal switch) is largely achieved by altering gut hormone levels that are responsible for hunger and satiety, leading to a new hormonal weight set point.[1] Bariatric surgery is a hormonal surgery in these procedures, for which the alteration in gut hormones develops as a result of the procedure’s restriction and malabsorption.[1]
Long-term studies show the procedures cause significant long-term loss of weight, recovery from diabetes, improvement in cardiovascular risk factors, and a mortality reduction from 40% to 23%.[2] The U.S. National Institutes of Health recommends bariatric surgery for obese people with a body mass index (BMI) of at least 40, and for people with BMI of at least 35 and serious coexisting medical conditions such as diabetes.[2] However, research is emerging that suggests bariatric surgery could be appropriate for those with a BMI of 35 to 40 with no comorbidities or a BMI of 30 to 35 with significant comorbidities. The most recent American Society for Metabolic & Bariatric Surgery guidelines suggest the position statement on consensus for BMI as an indication for bariatric surgery. The recent guidelines suggest that any patient with a BMI of more than 30 with comorbidities is a candidate for bariatric surgery.[3]
A National Institute of Health symposium held in 2013 that summarized available evidence found a 29% mortality reduction, a 10-year remission rate of type 2 diabetes of 36%, fewer cardiovascular events, and a lower rate of diabetes-related complications in a long-term, non-randomized, matched intervention 15–20 year follow-up study, the Swedish Obese Subjects Study.[4] The symposium also found similar results from a Utah study using more modern gastric bypass techniques, though the follow-up periods of the Utah studies are only up to seven years. While randomized controlled trials of bariatric surgery exist, they are limited by short follow-up periods.
