Purpose: The purpose of the study was to explore the utility of school- and county-level variables in explaining variability in children and adolescent body mass index (BMI).
Methods: BMI data from nearly 2.5 million of children and adolescents were aggregated at the school level from more than 5000 schools in Texas. School-level predictors included enrollment and the percentage of students qualifying for free and reduced lunch. Seven county-level variables were obtained from the County Health Rankings website, including adult obesity, food environment index, adult physical inactivity, access to exercise, college completion, childhood poverty, and income inequality. Multilevel modeling was used to examine school- and county-level predictors that may explain the variability in group level youth BMI.
Results: School-level socioeconomic status, school enrollment, and age-group were identified as significant predictors in youth BMI for both boy and girls. In girls, county-level adult obesity, food environment index, college completion, and income inequality were also significantly associated with youth BMI. In boys, the significant county-level predictors were food environment index and income inequality. Approximately 11%-16% of the variations in BMI Healthy Fitness Zone achievement were attributable to the differences between counties. The predictors included in the present study collectively explained approximately 50%-60% of between-county variation and 24%-47% of within-county variation.
Conclusions: The results of the current study advance research on the correlates that are associated with youth obesity at both school and county levels. These factors should be taken into account by policy makers and researchers interested in childhood obesity research.