Behavior, Biology and Bariatric Surgery Outcomes

Behavior, Biology and Bariatric Surgery Outcomes

I read with great interest the recent article, “Postoperative Behavioral Variables and Weight Change After Bariatric Surgery” by Mitchell et al published in JAMA Surgery.  The article is a longitudinal assessment of bariatric surgery in a multi center observational cohort. 10 hospitals participate in this cohort. A total of 2022 patients were recruited over a 3-year period and followed for at least 3 years after surgery. 1513 patients underwent Roux-en-Y gastric bypass surgery and showed 16% weight loss variability over the 3-year observation period following surgery. According to this study, this variability was explained by 3 behavior related variables including weekly self weighing, stopping to eat when feeling full and not eating continuously throughout the day. The authors found that those patients who started to self weigh after surgery, stopped eating when feeling full, and stopped eating continuously during the day after surgery lost 14% more body weight compared to those who did not.

The authors are to be congratulated on well written article and on their efforts to shed light on a much needed subject in bariatric surgery. What determines weight loss after weight loss surgery? Why do some patients loose more weight than others and how to best maintain weight loss several years after bariatric surgery? Obesity is a complex multifactorial problem. The “obesogenic” environment in which we live coupled with our genetic makeup is a perfect recipe for weight gain. It is quite amazing how bariatric surgery is able to reverse the damaging effects of our lifestyle leading to dramatic weight loss in a relatively short amount of time. By cutting or bypassing the stomach and more specifically the gastric fundus the interaction between ingested food and gastrointestinal tract changes. As a result, the secretion of a number of gastrointestinal hormones is altered in such a way to favor weight loss. Appetite and hunger decrease and the amount of ingested calories go down. The set point is reset and weight stabilizes at a new level. Each patient has a unique set point. Some patients loose 50% of their excess weight and others loose 90% in the first year after surgery. Several studies have attempted to determine weight predictors but failed to find one. Long-term weight loss after gastric bypass and sleeve surgery is however affected by the same factors that have caused obesity in the first place. A sedentary lifestyle and poor diet can reverse all the physiological changes brought by a gastric sleeve or bypass leading to obesity recurrence. The causes that lead to obesity in the first place, i.e. the “obesogenic” environment, are still present. Bariatric patients who succeed in maintaining the weight loss after gastric sleeve or bypass surgery are those who learn how to adopt and maintain a healthy lifestyle.  In other words, they use bariatric surgery as a tool to reset their metabolism but then maintain their weight by avoiding junk food, choosing lean proteins, eating vegetables and fruits, limiting their portions, weighing themselves and watching their weight, avoid skipping meals and grazing on food throughout the day… People tend to forget that metabolic surgery has no effect on our genetic make up or the environment in which we live. We cannot change our genes but we can definitely control our habits and lifestyles. Weight loss surgery is a bridge to a healthier you but maintaining this new state is up to you and only you. There is no doubt that bariatric surgery is not an easy way out for many of us. In today’s modern environment, we are all vulnerable to weight gain and regain after weight loss surgery. Mitchell and colleagues conclude in their study that structured behavioral programs must be created to help support bariatric patients after weight loss surgery. Even though patients have decided to become healthier by undergoing bariatric surgery, sustained change of behavior remains difficult.