Genetics Could Influence Success of Gastric Bypass Surgery

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For those trying to lose a significant amount of weight, gastric bypass surgery—a weight loss procedure that works by limiting the amount of food a patient can eat or absorb—can seem like a perfect, universal cure-all. But research from Massachusetts General Hospital (MGH) has found a way to use genetics to predict whether the surgery will actually result in the desired weight loss.

The MGH researchers studied the genomes of more than 1,000 patients who had gastric bypass surgery at the hospital over a 10 year period. The researchers found that participants with two copies of a gene found on chromosome 15 lost about 40 percent of their body weight while those with one copy lost around 33 percent and an individual with no copies of the gene lost less than 30 percent, suggesting that genetics influence how successful bypass surgery is. They also found that another gene close to the site could also predict percentage of presurgical weight lost, further strengthening their hypothesis. An MGH report quotes lead author Lee Kaplan:

“We know now that bypass surgery works not by physically restricting food intake but primarily through physiological effects – altering the regulation of appetite to decrease hunger and enhance satiety and increasing daily energy expenditure,” says Lee Kaplan, MD, PhD, director of the Obesity, Metabolism and Nutrition Institute at MGH and senior author of the report.  “Genetic factors appear to determine a patient’s response to gastric bypass, and the identification of markers that predict postoperative weight loss could provide important insight into those physiological mechanisms.”

This discovery is significant, first, because it suggests that genetic testing could help future potential gastric bypass surgery patients decide of the procedure is right for them. But the implications go beyond that, too. If bypass surgery is so closely associated with genes, the researchers believe it could be possible to develop drugs that target those genes in the first place, thereby cutting out the need for costly and invasive surgeries. In the report, Kaplan says:

“The fact that genetics appears to play such an important role in how well bypass surgery works in an individual patient gives us even more evidence that obesity results from dysfunction of the biological mechanisms that regulate fat mass and body weight and not solely from aberrant behavior or limited willpower,” he adds. “Identifying the involved genes opens up the potential for new classes of antiobesity therapies that mimic or exploit the molecular mechanisms so effectively used by gastric bypass.”