Association between natural amenities, physical activity, and body mass index in rural and urban North Carolina counties

Background: The USDA Natural Amenities Scale is an objective measure of the physical environment with applicability to research on the obesogenic environment. The purpose of this abstract is to examine associations between county-level natural amenities, physical activity, and body mass index (BMI). Methods: This was a cross-sectional study among 100 NC Counties. The Natural Amenities Scale includes the following: Warm winter, winter sun, temperate summer, low summer humidity, topographical variation, and water area. We gathered county-level covariates thought to have an independent association with BMI (percent rural, percent black, median age, median household income) from Census 2000. We obtained percentage of county residents meeting recommendations for physical activity, and self-reported height and weight from the NC Behavioral Risk Factor Surveillance System, years 2003, 2005, and 2007. We conducted weighted bivariate and linear regression analyses to examine relationships between natural amenities, physical activity, and BMI. Results: BMI and Natural Amenities were negatively associated (parameter estimate = -0.16 (0.06), p = 0.0056). When percent residents meeting physical activity recommendations was added into the adjusted model, the parameter estimate for amenities attenuated 18% (from -0.16 to -0.13). Conclusion: There was a significant inverse relationship between natural amenities and BMI, which was partially mediated by the percent of residents meeting physical activity recommendations. Natural amenities may moderate relationships between the built environment and both physical activity and BMI, and should thus be accounted for in analyses. Future research should determine if disadvantaged residents are more likely to live in areas with fewer amenities.