TUESDAY, Aug. 31, 2010 (HealthDay News) -- Exercise can reduce a person's genetic predisposition to obesity by 40 percent, finds a new English study.
Researchers looked at 20,430 people in Norwich and focused on genetic variants known to increase the risk of obesity. Most people had inherited 10 to 13 of these variants from their parents, but some had more than 17 while others had fewer than six.
The participants also provided information about their levels of physical activity.
Overall, each additional obesity-related genetic variant was associated with an increase in body mass index (BMI) equivalent to 445 grams (0.98 pounds) for a person 1.70 meters (5 feet, 6 inches) tall. BMI is a measurement that takes into account a person's height and weight.
However, this effect was greater in sedentary people than in active people, the researchers found. For those with a physically active lifestyle the increase was 379 grams (0.84 pounds) per genetic variant. That's 36 percent less than the increase of 592 grams (1.3 pounds) per genetic variant for inactive people.
The researchers also found that each additional obesity susceptibility variant increased the odds of obesity by 1.1-fold. But this risk was 40 percent lower for active people compared to inactive people, the findings revealed.
The study shows that adopting a healthy lifestyle can benefit people at increased genetic risk of obesity, the authors explained.
"Our findings further emphasize the importance of physical activity in the prevention of obesity," Dr. Ruth Loos, of the Medical Research Council's epidemiology unit in Cambridge and colleagues wrote in the article published online this week in PLoS Medicine.
The U.S. National Heart, Lung, and Blood Institute offers a guide to physical activity.