Dose-response relationship between walking and the attenuation of inherited weight

Objective. Genetic factors account for 40%-70% of the variation in body mass index (BMI). We sought to test whether moderate intensity physical activity affected parent-offspring relationships for body mass index and regional adiposity in 26,587 female and 6428 male walkers surveyed in the United States in 2000. Methods. Survey questionnaires provided self-reported usual walking distance, height, weight, and waist circumference, and mother's and father's adiposity (1 = lean, 2 = normal, 3 = overweight, and 4 = very overweight). Regression analyses were used to test whether the contribution of parental adiposities to the walkers' body mass indexes and waist circumferences diminished with walking. Results. In the most sedentary group (walking < 1.5 km/d), average parental adiposity was a significant determinant of the walkers' body mass indexes and waist circumferences (female: P < 10(-15); male: P < 10(-13)). Greater walking distance significantly diminished the effect of average parents' adiposity on the walkers' body mass indexes (female: P < 10(-10); male P = 0.003) and waist circumferences (female: P < 10(-5); male P = 0.01). Compared to the most sedentary female walkers, the effect of parental adiposity was reduced 36% for body mass indexes and 41% for waist circumferences (corresponding reductions in men were 36% and 46%, respectively). Conclusion. These results suggest that moderate intensity physical activity attenuates inheritance of both total and regional adiposity in a dose-dependent manner. (C) 2011 Published by Elsevier Inc.