Exercise Can Overpower the ‘Obesity Gene’

Study Shows Physical Activity Can Reduce the Effects of a Genetic Predisposition for Obesity.

By Denise  Mann

Reviewed by Laura J. Martin, MD

Nov. 2, 2011 — Obesity may be in your genes, but that is no excuse not to exercise.In fact, physical activity can reduce the effects of the ‘fat mass and obesity-associated’ (FTO) or obesity gene in adults. Previous research has shown that about 74% of all people in the U.S. with European ancestry have a genetic variation associated with the FTO gene that can lead to weight gain that raises the risk for becoming obese. According to the study,  the obesity-causing effects of the obesity gene are weakened by 30% when adults are physically active. The study is published in PLoS Medicine. “Despite the fact that you have the gene, there are things you can do to prevent it from influencing how heavy you are,” says Louis Aronne, MD, founder and director of the Comprehensive Weight Control Program at New York-Presbyterian Hospital/Weill Cornell Medical Center. He reviewed the study. “There is no question that the FTO gene is associated with an increased body weight,” he says. But “we can prevent these genes from taking their full course by doing something.” Genes — at least this one — are not destiny, Aronne says. “If you have the gene, that doesn’t mean it is over.” Aronne says people with the FTO gene should put on gloves and fight even harder. “There are things you can do and should do to fight it as hard as you can,” he says. Regular exercise tops this list. The study researchers agree: “Our findings … emphasize that physical activity is an effective way of controlling body weight, particularly in individuals with a genetic predisposition toward obesity,” they write. The findings contrast with the determinist view held by many that genetic influences are unmodifiable.” Researchers led by Ruth J. F. Loos of the Medical Research Council Epidemiology Unit in Cambridge, U.K. looked at data from more than 218,000 adults to confirm that this gene does increase risk for becoming obese. It does, but adults who exercised regularly had 33% lower odds of being obese compared to non-active adults.

Obesity Gene Testing

“It is a really exciting study that shows you can overcome your genes,” says researcher Paul Thompson, PhD. He is a professor of neurology at the David Geffen School of Medicine at the University of California at Los Angeles. Thompsonwas not involved in this study, but hehas conducted research on this gene in the past. “If you have this very severe obesity gene, you can reverse your risk with exercise. This gene makes you crave 200 more calories a day. That can be offset by walking two miles a day,” he says. This research may also help pave the way for new drugs that block the effect of the FTO gene, Thompson says. He thinks that testing for the gene could be beneficial. “This may motivate some people to exercise more.” Not everyone is on board with obesity gene testing. In an editorial published with the study, J. Lennert Veerman, PhD, writes that “testing for genetic traits that are associated with obesity makes no difference in the advice to overweight persons: increased physical activity and a healthy diet are indicated regardless of the genes.” Veerman is a senior fellow from the School of Population Health at the University of Queensland in Australia.