The built environment and obesity: A systematic review of the epidemiologic evidence
Introduction
Obesity prevalence has risen steadily over the past three decades. It is recognized as a major threat to public health, accounting for substantial disability and costs (Olshansky et al., 2005; Swinburn et al., 2004; Flegal et al., 2005, Flegal et al., 2004; Townsend, 2006; Brisbon et al., 2005; Serdula et al., 1993). At the individual level, obesity is the biological response to sustained positive energy balance. The observed population-scale shift toward larger body mass indexes (BMI), however, is the result of “mass influences” (Rose, 2001) that alter population rates rather than individual risk. Traditional explanations have centered on so called “lifestyle choices,” chiefly diet and physical activity (Weinsier et al., 1998). Biology and behaviors may govern individual risk, but, alone or in combination, do not explain the dramatic increase in prevalence over the past decades (Huang and Glass, 2008).
The importance of environment in population patterns of obesity was described a decade ago (Hill and Peters, 1998). Despite growing consensus on the environmental contribution (Swinburn et al., 2004; Peters, 2003; Hill et al., 2000) to obesity, overall progress in developing and testing hypotheses has been slow (Huang and Glass, 2008). Researchers from a large number of disciplines have been engaged in this investigation, including urban planning, transportation planning, landscape architecture, geography, economics, epidemiology, behavioral sciences, sociology, kinesiology, spatial statistics, leisure sciences, nutrition sciences, and others. A highly complex scientific literature has been the result and what is now needed is a critical appraisal of the extant evidence.
As currently conceptualized in the health literature, the built environment affects energy balance by presenting opportunities or barriers for physical activity (McCormack et al., 2004; Humpel et al., 2002; Handy et al., 2002; Saelens et al., 2003; Owen et al., 2004, Jackson, 2003; Jackson and Kochtitzky, 2001; Frumkin, 2002) and adherence to dietary recommendations (Zenk et al., 2005a, Jekanowski, 2001, Alter and Eny, 2005; Morland et al., 2002; Laraia et al., 2004; Wrigley et al., 2003; Rose and Richards, 2004; Haire-Joshu and Nanney, 2002). Prior reviews of the literature concluded that there is evidence of association between a variety of measures of the built environment and the risk of obesity but that uncertainty remains due to conceptual and methodological challenges (Booth et al., 2005; Papas et al., 2007; Black and Macinko, 2008). Given the pace of research in this field and the continuing impact of the obesity epidemic, we present a systematic and quantitative assessment of an updated body of literature focusing on conceptual, methodological, and inferential issues, with a particular emphasis on evaluating associations across studies, and provide recommendations for future research.
Section snippets
Methods
The purpose of this review was to evaluate the extant literature for evidence of association between the built environment and obesity. Our search in PubMed (National Library of Medicine, Bethesda, Maryland) included the medical subject headings (MeSH) “obesity” or “overweight” and “environment,” “built environment,” “transport,” “physical activity,” “green spaces,” “greenery,” “parks,” “neighborhood,” “food environment,” “nutrition environment,” and “food retail and access.” The search was
Evaluation of approaches across studies
Papers evaluated three domains of the built environment: the physical activity (31 papers), land use and transportation (34 papers), and food (22 papers) environments (Table 1). Associations were examined in both urban (60 papers) and rural settings (7 papers), and among adults (45 studies) and children (subjects less than 18 years of age, 21 studies; Table 2). Fifty-two papers were from the US, five from Australia, two from Canada, one each from Denmark, Sweden, and the UK, and one from a
Overview of evidence across studies
While it has become increasingly common (Swinburn et al., 2004; Peters, 2003; Hill et al., 2000) and theoretically sound to attribute the obesity epidemic, at least in part, to changes in the built environment over the past three decades, existing evidence does not identify a clear and strong role for built environmental risk factors with the possible exception of the county sprawl index and land use mix. We believe that despite the large number of studies, the great heterogeneity across
Conclusions and recommendations
The Surgeon General's Call to Action to Prevent and Decrease Overweight and Obesity 2010 (Burdette and Whitaker, 2004) states “individual behavioral change can occur only in a supportive environment with accessible and affordable healthy food choices and opportunities for regular physical activity.” Providing such a “supportive” environment is contingent on understanding the role of the built environment. While there is strong intuitive appeal to the notion that the built environment must be
Acknowledgements
We are grateful to Dr. Ana Navas-Acien for her advice on statistical issues and data interpretation.
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