Studying the Child Obesity Epidemic With Natural Experiments

Abstract

We utilize clinical records of successive visits by children to pediatric clinics in Indianapolis to estimate the effects on their body mass of environmental changes near their homes. We compare results for fixed-residence children with those for cross-sectional data. Our environmental factors are fast food restaurants, supermarkets, parks, trails, and violent crimes, and 13 types of recreational amenities derived from the interpretation of annual aerial photographs. We looked for responses to these factors changing within buffers of 0.1, 0.25, 0.5, and 1 mile. We found that cross-sectional estimates are quite different from the Fixed Effects estimates of the impacts of amenities locating near a child. In cross section nearby fast food restaurants were associated with higher BMI and supermarkets with lower BMI. These results were reversed in the FE estimates. The recreational amenities that appear to lower children's BMI were fitness areas, kickball diamonds, and volleyball courts. We estimated that locating these amenities near their homes could reduce the weight of an overweight eight-year old boy by 3 to 6 pounds.

Childhood Obesity and the Food Environment: A Population‐Based Sample of Public School Children in New York City

“…A recent review investigating neighborhood food environments and obesity found that most studies used cross‐sectional designs and that the relationships between food environments and weight status were mostly null . Furthermore, very few studies contended with endogeneity, and those that did focused on restaurants, mostly fast‐food restaurants . Our study adds to existing literature by examining multiple food outlet types around each child’s home.…”

“…The few studies that did find statistically significant results support the current understanding of the relationship between the food environment and obesity, in that obesity is positively correlated with proximity to fast‐food restaurants and inversely correlated with supermarkets. These studies have examined particular aspects of the food environment, that is, authors have looked at the effect of supermarkets or fast‐food restaurants on weight outcome . Another key limitation of these studies is that only a few have examined the food environment around children’s homes , including very small distances (of less than 0.1 mile) in urban areas .…”

“…These studies have examined particular aspects of the food environment, that is, authors have looked at the effect of supermarkets or fast‐food restaurants on weight outcome . Another key limitation of these studies is that only a few have examined the food environment around children’s homes , including very small distances (of less than 0.1 mile) in urban areas . Our prior work has found that, in New York City, public school children have enormous access to food outlets (both in terms of proximity to food outlets and the number of outlets available within walking distance), and that disparities exist .…”

“…Equally important, only a small number of studies have examined whether the relationship between access and child BMI is biased because of unmeasured neighborhood‐level confounders or selection into particular neighborhoods . For example, some studies have used fixed‐effects models at different levels to examine how variation in the food environment around homes affects weight outcomes . Others have used an instrumental variable strategy (proximity and/or access to a highway) to address endogeneity when examining the effects of fast‐food restaurant access on BMI .…”

Equity in Health and Health Care11This chapter was written when Marc Fleurbaey was research associate at CORE. We thank Chiara Canta, Tom McGuire, Tom van Ourti and Fred Schrogen for their useful comments.

“…Careful empirical research has shown, however, that cues in the environment may have a great impact on these decisions. The construction of recreational amenities (fitness areas) in Indianapolis led to a significant decrease in the BMI of children visiting pediatric clinics (Sandy et al, 2009). Posting the calorie content of foods and beverages in New York City Starbucks led to a lower consumption of food calories-even extending to the behavior of commuters who later visited other Starbucks establishments in cities where there was no calorie posting (Bollinger et al, 2011).…”