摘要：Despite growing support among public health researchers and practitioners for environmental approaches to obesity prevention, there is a lack of empirical evidence from intervention studies showing a favorable impact of either increased healthy food availability on healthy eating or changes in the built environment on physical activity. It is therefore critical that we carefully evaluate initiatives targeting the community environment to expand the evidence base for environmental interventions. We describe the approaches used to measure the extent and impact of environmental change in 3 community-level obesity-prevention initiatives in California. We focus on measuring changes in the community environment and assessing the impact of those changes on residents most directly exposed to the interventions. THE GROWING SUPPORT among public health researchers and practitioners for environmental approaches to obesity prevention 1 – 5 was confirmed in major consensus reviews by the Centers for Disease Control and Prevention (CDC) 6 and the Institute of Medicine (IOM). 7 , 8 Of the 11 recommended nutrition-related strategies proposed in the CDC review, 5 target the community food environment, in particular, the availability and accessibility of healthier food choices. Those strategies include increasing the availability and affordability of healthier food and beverage choices in public service venues, increasing the geographic availability of supermarkets in underserved areas, providing incentives to food retailers to offer healthier food and beverage choices and to locate in underserved areas, and restricting the availability of less healthy foods and beverages in public service venues. The consensus reviews also recommended a number of environmental approaches to promoting physical activity, in particular, changes to the built environment. Six of the 9 CDC-recommended strategies include improving access to outdoor recreational facilities, enhancing the infrastructure to support bicycling and walking, locating schools within easy walking distance of residential areas, improving access to public transportation, and zoning for mixed-land use development. The 2005 IOM Committee on Preventing Childhood Obesity created a national action plan that identified several immediate steps to address the obesity epidemic, including improving school food environments, promoting more active physical activity during the school day, expanding access to healthier foods in the marketplace, and expanding and promoting opportunities for physical activity across the community. 7 The support for environmental approaches reflected in the consensus reviews has been influential in shaping government and foundation initiatives aimed at preventing obesity, including the W. K. Kellogg Foundation's Food and Fitness Initiative, 9 the Robert Wood Johnson Foundation's Healthy Kids/Healthy Communities initiative, 10 the Department of Health and Human Services Communities Putting Prevention to Work Initiative funded under the American Relief and Reinvestment Act of 2009, 11 First Lady Michelle Obama's Let's Move Campaign, 12 and the White House Task Force on Obesity. 13 Despite the strong support for environmental approaches in the CDC and IOM reports, and in the research literature in general, there is a lack of empirical evidence showing that increasing the availability of healthy food promotes healthier eating or that changing the built environment increases physical activity. The CDC recommendations were based solely on expert panel ratings of strategies that have been mentioned prominently in the literature. The IOM panel on local government action assembled a wide range of literature and reports in support of their recommendations but did not attempt a systematic meta-analysis of the available intervention studies. The CDC Community Guide, 14 which makes recommendations based on available evidence, has no recommended strategies involving environmental change for either nutrition or obesity. The Community Guide does recommend built environment interventions to promote physical activity, including community-scale and street-scale urban design and land-use policies, and the creation of enhanced access to places for physical activity combined with informational outreach. 15 However, the urban design policy recommendation is based entirely on cross-sectional, observational studies, 16 leaving access to places for physical activity combined with outreach as the only environmental intervention with systematic evidence supporting its effectiveness. Other reviews from the epidemiological 17 and dietetic 18 literature have also found largely cross-sectional studies examining the relationship between the built environment and obesity. One reason for the lack of evidence is that the field is relatively new, and results from intervention studies are just now beginning to appear with regularity; in the area of access to healthy food in schools, see Hollar et al. 19 as an example, and in the area of access to healthy foods and physical activity for early elementary school students, see Shape up Somerville. 20 However, to our knowledge most environmental intervention studies have been cross-sectional studies that have documented the impact of increasing healthy food availability in neighborhoods (e.g., through healthier corner stores 21 , 22 ), and the few longitudinal studies we could find showed little or no impact (e.g., newly opened supermarkets in low-income neighborhoods 23 , 24 ). The lack of existing evidence about the effectiveness of environmental interventions makes it critical to carefully evaluate the growing number of community initiatives targeting environmental change. We describe the approaches used to measure the extent and impact of changes in the food and physical activity environments in 3 large, multisite, community-level obesity prevention initiatives: The California Endowment's Healthy Eating, Active Communities (HEAC) program, the California Endowment's Central California Regional Obesity Prevention Program (CCROPP), and the Kaiser Permanente Community Health Initiative (CHI). We describe the evaluation methods and discuss the challenges involved in measuring the extent and impact of environmental change.
