Do local employment centers modify the association between neighborhood urban form and individual obesity?

Extensive literature examines the relation between land use patterns and obesity, but less work explores whether local employment centers may reduce obesity. Local employment centers may affect obesity via providing agglomeration benefits such as increased job/transportation opportunities and closer proximity to local facilities/destinations. We utilized a large serial cross-sectional health survey from Los Angeles, California, conducted over three periods, to examine whether the presence of local employment centers modifies the association between land use patterns and individual body mass index. We retrieved individual health and sociodemographic data from the Los Angeles County Health Survey (2002, 2005, and 2007). To this Health Survey, we linked land use attributes at the census tract level collected from the Southern California Association of Governments. Our log-transformed regression models present interactions between local employment centers, neighborhood urban form features, and body mass index. Although most findings are consistent with previous studies, some of land use factors hypothesized to reduce the risk of obesity could have counterintuitive associations unless local employment centers were controlled. The unexpected results of our land use coefficients indicate that the tenet of New Urbanism may not necessarily promote health benefits. Our findings suggest that modifying the built environment may be effective in reducing obesity only in areas with high degree of local employment centers. Future studies would benefit from longitudinal and experimental, rather than cross-sectional, study designs that rigorously test the potential causal role of New Urbanism on obesity.