Competitive Food and Beverage Policies and Obesity among Middle School Students: Variability by Urbanicity in California.

This study examined the association between California school nutrition policies and population-level trends in childhood overweight/obesity by levels of urbanicity. We used interrupted time series with Fitnessgram data on overweight/obesity from the period 2002 to 2010 pertaining to African American, Latino, Asian, and White students in seventh grades who attended California public schools. We used multilevel logistic regression models to examine the impact of the introduction of successive California school nutrition policies on overweight/obesity prevalence, stratified by gender and adjusted for school district-, school-, and student-level characteristics. At the start of the study period, rural areas and second cities ( population centers with lower population densities than urban areas) had relatively low prevalence, but experienced sharp increases in 2002-2004, leading to higher prevalence of overweight/obesity than suburban areas. There was evidence of beneficial policy influences on overweight/obesity in most areas, except for girls in urban areas and boys in second cities. The evidence of beneficial changes was strongest among children attending schools located in rural areas, and boys in suburban and urban areas. These results persisted even after we accounted for differences in racial/ethnic compositions, socioeconomic characteristics of the schools and school neighborhoods, and school sizes, as well as child-level race/ethnicity, age, and student fitness levels. Despite evidence of beneficial policy impact, childhood obesity prevalence remains high, especially in urban areas in California. Additional policies and environmental interventions are recommended to address obesogenic risk factors unique to each area.