Obesity Surgery Does More than Meets the Eye

Obesity surgery works through more than simple mechanical manipulation of the GI tract. Obesity researchers have suspected this for some time and new research results are making it increasingly clear. Recent publications suggest that obesity surgery interacts with genes that affect obesity and with the microbiome — microbes in our gut that have so much to do with how we process and absorb food.

A new study published in Cell Reports found that weight loss after obesity surgery alters the expression of metabolic genes in muscle. “”The levels of specific genes that control how fat is burned and stored in the body are changed to reflect poor metabolic health,” says Juleen Zierath, senior author of the study. “After surgery, the levels of these genes are restored to a healthy state, which mirrors weight loss and coincides with overall improvement in metabolism.”

Another study, published in the new issue of the American Journal of Human Genetics, found a genetic variation that predicts how much weight a person will lose after gastric bypass surgery. “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, senior author of the study. “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.”

Finally, a growing body of evidence shows that the bacterial population in the intestines of people with obesity is very different from people with a lower BMI.  The intestinal bacteria in people who have lost weight after gastric bypass surgery more closely resembles the profile seen in people without obesity. Most recently, Kaplan and colleagues published a controlled study in mice showing that the altered profile of intestinal bacteria in fact causes the metabolic changes and weight loss associated with gastric bypass. Says Kaplan, “Now we need to learn more about how the microbiota exert their effects.”

Click here to read about the Zierath study in WebMD, click here to read the study itself, click here to read the Kaplan study in the American Journal of Human Genetics, and click here to read the Kaplan study of intestinal bacteria in gastric bypass.

DNA Purification image by Mike Mitchell from the National Institutes of Health / Wikimedia

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