Physical activity attenuates the influence of genetic predisposition to obesity, especially among older women, a recent study found. Researchers conducted a gene-environment study that included 8,206 women of European ancestry from the Women’s Health Initiative (WHI). They examined the main effects of the 95 single-nucleotide polymorphisms (SNP) body mass index (BMI) genetic risk score (GRS) and physical activity on BMI, and evaluated whether genetic associations are modified by physical activity (2-way interaction) and age (3-way interaction). They found:

• There was evidence for modification of the BMI GRS-BMI association according to both physical activity and age.
• A significant 2-way interaction of BMI GRS x physical activity in the crude model was observed, where there was a smaller effect of the BMI GRS on BMI with increasing physical activity.
• The beta coefficient was 0.05 for the high-activity group vs beta = 0.13 for the sedentary group.
• The 3-way interaction was statistically significant.
• The BMI GRS-BMI association was attenuated and no longer significant in the high activity group among those in group aged >70 years.