Is longer better? The effects of duration of exposure to school wellness policies on adolescent obesity

School-based wellness policies have been implemented with the intent of reducing childhood obesity. This analysis evaluated how duration of exposure to such policies effects the risk of adolescent overweight and obesity. Data was extracted from the 1990-1992 birth cohort of the Utah Population Database (n=51,475), a data registry that genealogically links state administrative records such as birth certificates for all residents of Utah. Obesity/overweight risk was assessed based on self-reported height and weight at the time of a child's first driver's license. Familial characteristics such as mother's body mass index, educational attainment, and marital status were taken from the child's birth certificate. District-level socio-demographics and wellness policies were appended via geocoded residential addresses. A school district's commitment to wellness was assessed through each district's implementation of nutritional, physical education, and general wellness polices in response to the 2004 Child Nutrition and WIC Reauthorization Act. All models were estimated using logistic regression, with controls for spatial clustering. The longitudinal effects of competitive food, physical activity, and overall wellness policies on adolescent overweight/obesity were estimated. Results demonstrated longer duration of exposure to wellness policies, particularly competitive food and physical education, to be associated with significantly increased reductions in adolescent overweight and obesity. Beyond simple exposure, these results support the conclusion that consistent application of wellness policies may be required to effectively combat childhood obesity within the school environment.