Study evaluates success of weight loss surgery

In an attempt to understand what makes some patients with obesity respond better to surgery than others, Professor and Chair of Epidemiology Alison Field and her team analyzed over 10,000 patients who received weight-loss surgery. They found that patients that binge ate were able to lose weight more easily than those whose obesity was likely more rooted in genetics. According to Field, “We let the data tell us the story. We put in body weight, history of body weight, eating behaviors, hormone levels, factors related to cardiometabolic health, and asked how do these naturally cluster together?”

Field’s final model outlined four distinct subgroups that each responded differently to the surgery. Field’s team studied patients for three years following bariatric surgery, which is commonly known as weight-loss surgery. Previous studies have shown that losing weight improves eating habits, creating a positive feedback loop. This factor could possibly explain the sustained weight loss among binge eaters, Field said, since they may have changed their eating behavior.

According to Leonidas Bleris, associate professor of bioengineering at the University of Texas at Dallas who was unaffiliated with the study, obesity “is a complex problem. It has to do with a lot more than just genetics.” Bleris explained that other factors as wide-ranging as the diet of your parents to medical history affect how you process food.

Field’s group accounted for a much larger variety of factors than most other obesity classification studies, according to Jim Mitchell, a research scientist at the Neuropsychiatric Research Institute and a co-author of the paper. The dataset covered a wide range of factors, including psychological behavior, medical records and eating habits, he added.

What really makes this study unique is the size of the dataset that Field was using, Mitchell said. “It’s very unusual to have a sample of patients this large with this much follow-up data.” 

While the findings preliminarily suggest that treatments be personalized for different subgroups, further studies need to replicate the results before any doctors start treating patients differently, Mitchell said. The study identified subgroups that lost weight differently, but researchers have yet to determine the role that genetics play in controlling these differences, he added.

Field hopes that other researchers are inspired by her work and attempt to recreate her findings, eventually leading to clinical applications.

She also aims to examine obesity in teenagers using a similar data set collected by Mitchell that focuses on younger patients. “There are fewer ways you can develop extreme obesity when you’re younger. … There’s probably a stronger genetic component, so we want to see (if)we see the same subgroups when they’re younger,” she said. She hopes to use this information to develop targeted treatments for young adults. 

While the group found varied results among different types of patients, “overall bariatric surgery is by far the best treatment we have for severe obesity. It’s the only treatment we have that’s likely to result in sustained weight loss and marked improvement. It works for just about everybody. It just worked a little bit better for some people,” Mitchell said. 

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