Walking briskly for an hour a day can help those with a genetic tendency toward obesity, U.S. researchers said. Study author Qibin Qi, a postdoctoral research fellow at Harvard School of Public Health in Boston, and colleagues said the study examined 7,740 women and 4,564 men from the Nurses\' Health Study and Health Professionals Follow-up Study -- involving men working in the healthcare industry. Researchers collected data on physical activity and TV watching two years prior to assessing body mass index, and calculated a genetic predisposition score based on 32 established BMI-predisposing genetic variants. \"While previous studies have looked at how physical activity affects genetic predispositions, this is the first study that directly looked at the effect of the sedentary behavior of television watching on the BMI of individuals with a genetic predisposition to obesity,\" Qi said in a statement. \"In our study, a brisk 1-hour daily walk reduced the genetic influence toward obesity, measured by differences in BMI by half. On the other hand, a sedentary lifestyle marked by watching television 4 hours a day increased the genetic influence by 50 percent.\" The findings were presented at the American Heart Association\'s Epidemiology and Prevention/Nutrition, Physical Activity and Metabolism scientific sessions in San Diego.