Although we cannot change our genome sequence, we can influence some of the effects of our genes. Researchers found that in adults, physical activity may reduce the risk for obesity associated with certain variants of the FTO gene. Knowing that people can have different forms of the FTO gene, which vary slightly in their gene sequences, the researchers compared people who have a form of the FTO gene that increases risk for obesity with individuals who have another form of the gene. Because previous reports had conflicting results as to whether physical activity can attenuate this risk, the team of researchers decided to analyze more people. To do this, they compiled information on FTO gene sequences and physical activity for over 218,000 adults who had participated in a variety of other studies. For the new analysis, the researchers defined adults as “inactive” if they had sedentary jobs and less than an hour per week of moderate to vigorous activity during leisure time or commuting, or if their activity levels were otherwise particularly low compared to other participants of their respective study. Those with higher activity levels were considered “physically active.” Overall, they found that people with the adverse FTO gene variant were more likely to be obese than those with the other form of the FTO gene. Encouragingly, physical activity reduced this risk by 27 percent. In a similar analysis of over 19,000 children, the researchers found that physical activity, which was defined slightly differently for this age group, did not seem to attenuate FTO-specific risks for obesity, and it did not correlate with the children’s body mass index (a measure of weight relative to height). However, physical activity did appear to be helpful for children in general, as those who were physically active had less body fat and a smaller waist circumference than inactive children. Other studies of the FTO gene have found that adverse FTO variants seem to drive people to eat more, particularly high-fat foods. It is not clear how, in adults, physical activity may reduce obesity risk conferred by the FTO gene, or whether the reduced risk may be due to a combination of lifestyle factors. For example, adults who are physically active might also tend to have healthier eating habits than those who are sedentary. These results offer hope of reducing obesity risk for the many people with this FTO gene variant, and emphasize the value of both individual behaviors and environments that promote healthy lifestyles, regardless of one’s genetic predisposition.
Kilpeläinen TO, Qi L, Brage S, et al. Physical activity attenuates the influence of FTO variants on obesity risk: a meta-analysis of 218,166 adults and 19,268 children. PLoS Med 8: e1001116, 2011.