The Built Environment, Obesity and Walking
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This dissertation focuses on the influence of the built environment on the geographic distribution of walking behavior and the obese epidemic. Fundamentally, obesity results from energy imbalance. The study aims to help planners understand how to change neighborhood environment in order to reconstruct energy balance: decreasing energy intake by supplying healthy food environment and increasing energy output by introducing physical activity supporting environment. Neighborhood-level factors are hypothesized to influence obesity and walking behavior via exposure and access mechanisms (Feng et al., 2010; Moudon et al., 2007; Saelens and Handy, 2008). The hypothesis raises the following questions for this dissertation to answer: Does obesity cluster in space? Where and why does obesity cluster? How much walking occurs around home? What home neighborhood built environment characteristics are indeed associated with walking? How may individuals change their walking behavior after introduction of light rail? By answering the questions above, the dissertation presents new evidence for future prevention studies: The geographic distribution of obesity is not random and related to neighborhood property value and residential density. Taking Seattle King County as an example, this area presents a north to south obesity gradient, with the northern part being less obese, richer and more densely populated and the southern part being more obese, lower income, and less densely populated. In terms of walking, the evidence that over half of walking occurs within the home neighborhood emphasizes the importance of the role of the home neighborhood in promoting physical activity. Higher residential and job density, which correlate with high street intersection, sidewalk and fitness density, would effectively support walking behavior in home neighborhoods. Also, after the introduction of light rail, people tend to walk more in station areas, which implies that rail transit may help increase the number of potential customers for retail and service near station areas. This dissertation has limitations that point to areas of future research. The circular shapes used to detect obesity clusters may not really represent the boundary of a neighborhood. In reality, neighborhood boundaries have complex shapes (Kulldorff et al., 2006; Patil and Taillie, 2004; K Takahashi et al., 2008). More research needs to be done on incorporating detection methods with neighborhood boundaries usually separated by natural obstacles such as lakes or rivers. Finally, more natural experiments with longer assessment period need to be carried out to compare walking behavior in free-living daily activities before and after interventions.
- Urban planning