Childhood obesity prevention and obesogenic school environments

Background: Modern school environments, labeled as "obesogenic" or "toxic", have been explicitly identified as contributors to the growing childhood obesity epidemic that arguably began in the 1980s and as ideal settings for prevention and interventions. And given that the underlying mechanisms of the epidemic are acknowledged as high caloric-dense intake and insufficient physical activity (PA), states have been responding to the epidemic by adopting new school policies via legislation, state board of education, or state agency action. Such actions occur within an ecological model where policies are a part of and affect the school context that shifts the policy focus from health behavior change to addressing influences that channel and create patterns of health behavior.;Purpose: The study purpose herein assessed variation in the dose-response relationship between exposure to obesogenic school PA policy doses, the dose-delivered and students' moderate to vigorous PA (MVPA) behavioral response patterns in physical education (PE) class coupled with change in students' BMI outcomes in an ethnically diverse public middle school adolescent girl population.;Specific Aims: Using secondary data, the specific aims of the study herein was to: 1) examine the effects of variation across obesogenic schools' PA policy dose, coupled with the policy dose-delivered and MVPA response patterns in school PE class from 2003 to 2005 on change in students' BMI in an ethnically diverse public middle school adolescent girl population and, 2) test the hypothesis that variation in the decrease of leptogenic or nontoxic school PA policy doses across schools and PE classes are positively correlated with students' increasing BMI outcomes in public middle school adolescent girls.;Methods: The study herein used a nonexperimental contextual correlation design (limited longitudinal) with Hierarchical Linear Modeling (HLM) analytic methods to answer both the posed research question and test the previously stated hypothesis.;Findings: Primary results for the evaluative two-level school effects model showed three of the 12 sixth grade predictors were significant: BMI6, t=67.10, SE=.02, p<.001; Student SES (Y), t=-2.42, SE=.13, p<.05; and Percent Minority Enrollment, t=-2.69, SE=.01, p<.01. The interaction two-level school effects model showed significant results for BMI6, t=14.22, SE=0.06, p<0.001; Student SES (Y), t =2.45, SE=0.13, p<0.01; Percent Minority Enrollment, t=-2.63, SE=0.01, p<0.01; Policy Dose, t=-2.33, SE=0.01, p<0.05; and Policy dose*BMI6, t=1.98, SE=0.00, p<0.05. This interaction suggests that as policy increases the inheritance factor of BMI increases and as BMI increases the effect of policy decreases.;Conclusion: School PA Policy dose matters as critical structure of obesogenic school contexts. It can be argued that policy dose is somewhat endogenous given the 'inheritance factor of BMI'. Hence, school PA policies for PE are working best for students that are already maintaining a healthy body weight between the 5th and 85th BMI age-for-girl specific percentile. The findings herein suggest that policy-based prevention and interventions within obesogenic school environments need to be targeted toward overweight minority adolescent girls in public middle schools who are 'at risk' for the onset of childhood obesity. Further because policies are a part of and affect the school context, future research is needed in addressing influences that channel and create patterns of health behavior within macro-micro obesogenic school 'living' environments.