UCLA

The prevalence of obesity among US children and adolescents has rapidly increased in the past several decades, and the epidemic of childhood obesity is currently a serious public health concern in the United States. This dissertation consists of three studies examining individual- and neighborhood-level determinants of childhood obesity. The study area was Los Angeles County in California. Our first study examined the effects of maternal employment, individual socioeconomic status (SES), and neighborhood SES on childhood obesity. The second study not only investigated the independent effect of neighborhood food environment on childhood obesity, but also examined the mediation and moderation effects of household grocery shopping distance on the relationship between neighborhood food environment and childhood obesity. The third study assessed the comparability of two commercial (i.e., InfoUSA and Dun & Bradstreet) and one government (i.e., Los Angeles County Department of Public Health) food environment databases which can be used to measure neighborhood food environment.

Our main findings indicated that maternal part-time employment was associated with increased child's BMI, and children's TV-watching time mediated this relationship. In addition, both individual- and neighborhood-level SES measures were inversely associated with childhood obesity. We also found that children living in neighborhoods with lower density of supermarkets and grocery stores or living in neighborhoods with higher density of convenience stores were more likely to have higher BMI. Findings from our comparison study reported that for the InfoUSA vs. Dun & Bradstreet comparison, similarity of counts was high for supermarkets & grocery stores and convenience stores. For Los Angeles County Department of Public Health vs. Dun & Bradstreet comparison, similarity of counts was high for chain supermarkets, independent grocery stores, meat and fish markets, sweets stores, and bakeries; similarity was low for fast-food stores and liquor stores. Census tract characteristics (i.e., median income, percent minority) were associated with levels of similarity across databases.

This dissertation identified that maternal part-time employment, individual and neighborhood SES, and neighborhood food environment may be important determinants of childhood obesity. For the measure of neighborhood food environment, the accuracy of secondary data sources remains a considerable issue and additional validation studies are recommended.