To our knowledge, this is the first study to examine the relationship between physical activity and obesity by state. Our findings show a highly significant positive association between insufficiently physically active and the prevalence of obesity at the national level that remained after adjusting for age, race, gender, and median household income. Insufficiently physically active accounted for ~20% of the state-level variance in the prevalence of obesity after controlling for state-level demographic factors that are associated with physical activity and obesity. This finding is an important first look into disparities in the prevalence of physical activity and the impact on state-level prevalence of obesity across the United States. Many of the state-level demographic variables are not malleable, such as age, race, and gender, but this report demonstrates that participation in physical activity, at the state-level, might be a robust factor that affects the prevalence of state-level obesity. The wide variation in physical activity and obesity across the Unites States, which transcends common state-level demographic characteristics, lends credence to the conjecture that environmental constructs might be important future research and intervention targets.15
Similarly, Sharpe and colleagues16
reported an inverse association between BMI and physical activity in individuals in South Carolina using 2001 BRFSS data. Notably, in the aforementioned report, SES has been implicated as an important factor that influences physical activity participation rates, but it should be noted that obesity and physical inactivity continue to increase across all SES groups, and participation rates in physical activity among lower SES groups is commonly reported as having community and environmental origins.13,15,17,18
Health promotion campaigns have been primarily focused on education and evoking action at the individual level, and these efforts have had little impact on the prevalence of physical activity at the national level.15
Conceivably, environmental factors are mitigating these efforts, and greater emphasis needs to be placed on implementing environmental and community adaptations that allow for greater participation in physical activity (ie, walkable communities, access to recreational facilities, bike paths, etc). A logical first step as highlighted from the current study is to elucidate underlying mechanisms in environmental and cultural disparities between states such as Colorado that have higher rates of participation in physical activity and lower prevalence of obesity and states such as Mississippi that have lower rates of participation in physical activity and higher prevalence of obesity.
Environmental and sociopolitical factors have been postulated to explain some of these differences and may exert a more potent influence on the increasing prevalence of obesity than previously thought.19
In the past decade, research exploring environmental factors (ie, built environment) has increased, and environmental changes such as the increased use of technology and urban sprawl have been implicated in the reduction of both occupational and leisure-time physical activity.19
Coupled with greater food availability, these changes to the built environment have contributed to an “obesogenic” or “toxic” ecosystem that contributes to sedentariness and obesity. In the current report, caloric data were not available, which would have strengthened the current analysis, but currently no data exist, nationally. Because nutrition and physical activity are intricately linked with the prevalence of obesity, caloric disparities as well as nutrient intake across the Unites States would provide additional insight into the clustering of behaviors that convey a propensity for the obesogenic milieu. To date, much remains unknown about sociopolitical and macroenvironmental differences across states that contribute to this deleterious ecosystem that might remove or place barriers to participation in physical activity and concurrently result in higher state-level obesity rates.
Each state in the Unites States has been given the charge to meet the Healthy People 2010
targets for reduction in the prevalence of obesity.12
To support these efforts, several campaigns have been developed by the CDC to target individual-level behaviors such as the CDC’s Nutrition and Physical Activity Program to Prevent Obesity and the Steps to a Healthier US.20,21
Collaboration with local governments, city planners, media outlets, schools, and employers to not only influence individual behaviors, but to reduce community barriers that limit opportunities to be more physically active, is essential. However, much still remains unknown about the effectiveness of community-based initiatives that promote community and individual support for adopting a more physically active lifestyle, which makes these projects difficult to fund. The current data provide evidence that there are wide variations in physical activity participation across the United States, and these variations have a substantial impact on the prevalence of obesity. At this juncture, with the majority of the US population overweight or obese and insufficiently active to promote health or completely sedentary, it appears critical to examine and develop a better understanding of environmental influences across the spectrum that influence clustering of behaviors such as physical activity (ie, Colorado versus Mississippi). These endeavors might provide insightful information into unique factors that can be addressed to enhance the likelihood of sustainable environmental interventions that increase physical activity participation and reduce obesity and sedentariness. In the short term, even if the prevalence of physical activity was increased, the effect on obesity prevalence might be modest. Nonetheless, increasing physical activity participation has been reported to prevent further unhealthy weight gain,9
and, even in the absence of weight loss, physical activity has a salutary effect on many obesity-related sequelae.22
In conclusion, the prevalence of insufficiently physically active is associated with the prevalence of obesity nationally and accounts for a considerable amount of the state-level variation in obesity that transcends demographic characteristics. Further examinations into cultural, environmental, and sociopolitical disparities between states is needed to identify and clarify potentially modifiable factors that prevent a physically active lifestyle at the population level, and perhaps the next step is to closely examine these variables in states that currently have high rates of participation in physical activity and low prevalence of obesity and vice versa.