Watching too much TV can worsen your genetic tendency towards obesity, but you can cut the effect in half by walking briskly for an hour a day, researchers report at the American Heart Association’s Epidemiology and Prevention/Nutrition, Physical Activity and Metabolism meeting this week. “In our study, a brisk one-hour daily walk reduced the genetic influence towards obesity, measured by differences in BMI by half. On the other hand, a sedentary lifestyle marked by watching television four hours a day increased the genetic influence by 50 percent,” said Qibin Qi, the study’s author. The researchers calculated a genetic predisposition score based on 32 established BMI-predisposing genetic variants.