Howard et al. BMC Public Health 2011, 11:68 http://www.biomedcentral.com/1471-2458/11/68 R E S E A R C H A R T I C L E Open Access Proximity of food retailers to schools and rates of overweight ninth grade students: an ecological study in California Philip H Howard1*, Margaret Fitzpatrick1, Brian Fulfrost2 Abstract Background: The prevalence of obesity and overweight in youth has increased dramatically since the 1980s, and some researchers hypothesize that increased consumption of low-nutrient, energy-dense foods is a key contributor. The potential importance of food retailers near schools has received increasing attention, but public health research and policy has focused primarily on fast food restaurants. Less is known about the relationship between overweight/obesity and other types of retailers. This study aims to investigate the potential associations between nearby 1) fast food restaurants, 2) convenience stores, and 3) supermarkets, and rates of overweight students in California schools. Methods: We examined the rate of overweight ninth grade students in public schools in 2007 using linear regression. The percentage of overweight students per school was determined by a state required physical fitness test, with three different options for measuring individual body composition. Our key independent variables were the presence of three different types of retailers within 800 m network buffers of the schools. Additional independent variables included school ethnic, gender and socioeconomic composition, as well as urban/non-urban location. We obtained the data from the California Department of Education and ESRI, Inc. Results: The presence of a convenience store within a 10-minute walking distance of a school was associated with a higher rate of overweight students than schools without nearby convenience stores, after controlling for all school-level variables in the regression (1.2%, 95% confidence interval 0.03, 2.36). Nearby fast food restaurants and supermarkets, however, were not associated with school rates of overweight students. Conclusions: Public health researchers and policy-makers interested in the food environments outside schools should expand their recent focus on nearby fast food restaurants to include convenience stores, which may also be important sources of low-nutrient, energy-dense foods for students. Background The rate of child and adolescent obesity in the United States has increased threefold since 1980, and although currently steady, remains at 17% [1]. Excess weight in children and young adults is associated with greater risks for diabetes, cardiovascular disease and certain cancers [2], as well as associated economic costs [3]. A number of studies have implicated increased con- sumption of low-nutrient, energy-dense foods such as * Correspondence: howardp@msu.edu 1Department of Community, Agriculture, Recreation and Resource Studies, Michigan State University, 316 Natural Resources, East Lansing, MI, 48824, USA Full list of author information is available at the end of the article sugary drinks and fast foods as a factor in elevated rates of overweight and obesity [4-7]. Recently, both researchers and policy-makers have increased their attention on the role of retailers in pro- viding access to these foods as a potential risk factor for increased body fat [8]. Although our understanding of these potential relationships remains limited, several stu- dies focusing on children and young adults in the US have reported associations between food environments and weight status. Residing near fast food restaurants [9] and convenience stores, for example [10,11], is asso- ciated with excess weight, while residing near supermar- kets is associated with lower weight [11,12]. While not all studies have observed these types of associations © 2011 Howard et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.