CAMBRIDGE, England—Shoppers who feel their genes are the reason they have weight problems may want to reconsider exercise routines. A new study found genetic predisposition to obesity can be reduced by approximately 40 percent by having a physically active lifestyle (PLoS Med 7(8): e1000332. doi:10.1371/journal.pmed.1000332).
The findings of this study suggest, while everyone benefits from increased physical activity, individuals who are genetically predisposed to obesity would benefit more than genetically protected individuals. Furthermore, these findings challenge those who feel it’s their genetic predisposition to obesity that causes their weight issues.
The researchers used a population-based cohort study of 20,430 people living in Norwich, England (The EPIC-Norfolk study), and identified individuals who were 39 to 79 years old between 1993 and 1997. The researchers used genotyping methods and calculated a genetic predisposition score for each individual, and their occupational and leisure-time physical activities were assessed by using a validated self-administered questionnaire. Specifically, they were looking for 12 alleles (a DNA variant that is located at a specific position on a specific chromosome) known to increase the risk of obesity, the amount of activity, and their effects on body mass index (BMI) and obesity risk.
The researchers found each additional BMI-increasing allele was associated with an increase in BMI equivalent to 445 g (1 pound) in body weight for a person 1.70 m (5 feet, 5 inches) tall, and that the size of this effect was greater in inactive people than in active people. In individuals who have a physically active lifestyle, this increase was only 379 g (0.8 pounds)/allele, or 36-percent lower than in physically inactive individuals in whom the increase was 592 g (1.3 pounds)/allele. Furthermore, in the total sample, each additional obesity-susceptibility allele increased the odds of obesity by 1.1-fold. However, the increased odds per allele for obesity risk were 40-percent lower in physically active individuals compared to physically inactive individuals.