Individuals who are genetically predisposed to obesity can prevent weight gain by being physically active, according to findings from a Finnish study of young adult twins.
The investigation involved more than 4,000 monozygotic and dizygotic twins, aged 22–27 years (average age 25), who were enrolled in a population-based longitudinal twin study.
Dr. Linda Mustelin of the University of Helsinki and her associates evaluated the impact of physical activity on the degree to which genetics influences body mass index and waist circumference, using quantitative genetic analyses of data from the twins and their families.
A high level of physical activity significantly modified the heritability of BMI and waist circumference, which they said was a new finding. Specifically, the analysis showed an inverse relationship between physical activity and waist circumference in males (r = −0.12) and females (r = −0.18), and between physical activity and BMI in females (r = −0.12).
The findings are consistent with previous studies suggesting that physical activity helps prevent obesity, but “most importantly, this study demonstrates that a physically active lifestyle is able to counteract genetic predisposition to obesity,” they concluded (Int. J. Obes. 2009;33:29–36).
Only a few studies have looked specifically at individuals with a genetic predisposition to obesity and the impact of physical activity on their weight.
They cited changes in expression patterns of genes regulating weight and adiposity as a possible mechanism.