July 10, 2013
Obesity and lack of physical activity are associated with several chronic conditions, such as heart disease and diabetes, increased health care costs, and premature death. Since different local governments have pursued different approaches to address both risks, levels of obesity and physical activity are likely to vary substantially across counties. To understand local trends in physical activity and obesity that would help identify successful and less successful strategies, researchers examined county-level changes in physical activity and obesity between 2001 and 2011.
The researchers used data from the Behavioral Risk Factor Surveillance System (BRFSS), a state-based random-digit telephone survey that covers the majority of United States counties, and the National Health and Nutrition Examination Survey (NHANES), a nationally representative sample of the US civilian noninstitutionalized population. They calculated body mass index (BMI) from self-reported weight and height in BRFSS, adjusting for self-reporting bias using NHANES, and calculated self-reported physical activity—both any physical activity and physical activity meeting recommended levels—from self-reported data in BRFSS. To generate estimates of obesity and physical activity prevalence for each county annually for 2001 to 2011, they used validated small area estimation methods.
Results showed that physical activity in US counties is increasing. Levels were generally higher in men than in women, but increases were greater in women than men, and counties in California, Florida, Georgia, and Kentucky reported the largest gains. However, this increase in level of activity was matched by an increase in obesity in almost all counties during the same time period. Increases in physical activity in counties were not shown to be strongly related to decreases in obesity – from 2001 to 2009, for every 1 percentage point increase in physical activity prevalence, obesity prevalence was 0.11 percentage points lower, controlling for changes in poverty, unemployment, number of doctors per 100,000 population, percent rural, and baseline levels of obesity.
While the increases in physical activity seen at the county level will have a positive impact on the health of Americans, these increases have a small impact on the prevalence of obesity. This means that other strategies are likely needed. Coordinated actions involving the health care and public health systems, non-governmental organizations, and food labeling, taxation, and incentive programs should be considered to curb the obesity epidemic and its burden.
Dwyer-Lindgren L, Freedman GD, Engell RE, Fleming TR, Lim SS, Murray CJL, Mokdad AH. Prevalence of physical activity and obesity in US counties, 2001-2011: a road map for action. Population Health Metrics. 2013; 11:7.