Fast-Food Consumption and the Fast-Food Environment

Abstract

Background: Nearly one-third of Americans are obese, and two thirds are overweight. While sedentary lifestyles are part of the cause, a diet of processed foods, such as fast-food, also shares much of the blame. Fast-food restaurant exposure has been positively correlated with higher BMI and lower socioeconomic status. However, there is a lack of causal evidence linking residing in a fast-food dense area with increased frequency of fast-food consumption. Also, emerging evidence suggests that fast-food restaurant variety may play a larger role than density in understanding consumption. Little research exists on how socio-economic factors, such as neighborhood level deprivation, may affect this relationship. Methods: The population included 748 same-sex twin pairs living in the Puget Sound. Data on fast-food density, fast-food variety, and fast-food consumption frequency came from the University of Washington Twin Registry and public and commercial geospatial data bases. Fast-food density was calculated as the number of fast-food restaurants available within a 3km radius of each subject's home address, and fast-food variety was the number of different chains available within that same radius. Fast-food density and variety were regressed against fast-food consumption frequency, using a generalized estimating equation and ordinary least squares through the origin to account for both between and within twin pair correlations in upbringing and genetics. All models controlled for individual measures of sex, income, and education. Mean neighborhood property values were added to the last model. Results: No statistically significant associations were found between fast-food density/variety and consumption, regardless of model, adjustments, or neighborhood size. Both the GEE and logistic regression analyses indicated that an increase in the presence of fast-food restaurant was associated with decreased consumption, although the results lacked statistical significance and were of negligible magnitude. Discussion: The lack of association between fast-food restaurant density/variety and consumption may be due to several factors, including the impact of exposures at other locations (e.g., work and school), the low fast-food consumption in the sample, and the convenience of automobiles diminishing the impact of neighborhood-level exposures. How the fast-food environment may influence consumption needs to be better understood to guide future efforts against obesity.