The obesity epidemic and the metropolitan-scale built environment: Examining the health effects of polycentric development

Existing research on how the built environment affects physical activity and obesity has mainly focused on neighbourhood-scale features, such as land use mix, street connectivity and density. This research hypothesises that metropolitan-scale built-environment characteristics, such as polycentricity, should also play an important role. The impacts of the metropolitan built environment on individual travel behaviour will further affect how individuals allocate their time for sedentary activities, moderate physical activities and vigorous exercise, which in turn should affect individual weight status. This research uses the American Time Use Survey from 2003 to 2007 and spatial statistical polycentricity metrics for hypothesis testing. A multi-level path analysis reveals that living in a relatively polycentric region is significantly associated with a lower obesity probability with multiple paths: individuals living in relatively polycentric regions tend to spend less time on sedentary activities and more time on moderate-to-vigorous physical activities, which increases their daily energy expenditure; beyond the linkage to energy expenditure, living in a relatively polycentric region is directly associated with a lower obesity probability, which suggests other ways that the polycentric structure influences individual weight status. This research furthers the literature by examining how the formats of metropolitan spatial development are relevant to broader issues of individual lifestyles and public health. The results suggest that regionwide efforts to cultivate suburban centres of increased density could lead to significant public health benefits.