How Food Environment Impacts Dietary Consumption and Body Weight: A Country-wide Observational Study of 2.3 Billion Food Logs

Abstract IMPORTANCE An unhealthy diet is a key risk factor for chronic diseases including obesity, diabetes, and heart disease. Limited access to healthy food options may contribute to unhealthy diets. However, previous studies of food environment have led to mixed results, potentially due to methodological limitations of small sample size, single location, and non-uniform design across studies. OBJECTIVE To quantify the independent impact of fast food and grocery access, income and education on food consumption and weight status. DESIGN, SETTING AND PARTICIPANTS Retrospective cohort study of 1,164,926 participants across 9,822 U.S. zip codes logging 2.3 billion consumed foods. Participants were users of the My-FitnessPal smartphone application and used the app to monitor their caloric intake for an average of 197 days each (min 10, max 1,825 days, STD=242). MAIN OUTCOMES AND MEASURES The primary outcomes were relative change in consumption of fresh fruits and vegetables, fast food, and soda, as well as relative change in likelihood of overweight/obese body mass index (BMI), based on food consumption logs. Food access measures for each zip code were computed from USDA Food Access Research Atlas and Yelp.com, and demographic, income and education measures were based on Census data. Genetic Matching-based approaches were used to create matched pairs of zip codes. RESULTS Access to grocery stores, non-fast food restaurants, income, and education were independently associated with healthier food consumption and lower prevalence of overweight/obese BMI levels. Substantial differences were observed between predominantly Black, Hispanic, and White zip codes. For instance, within predominantly Black zip codes we found that high income was associated with a decrease in healthful food consumption patterns across fresh fruits and vegetables and fast food. Further, high grocery access had a significantly larger association with increased fruit and vegetable consumption in predominantly Hispanic (7.4% increase) and Black (10.2% increase) zip codes in contrast to predominantly White zip codes (1.7% increase). CONCLUSIONS AND RELEVANCE Policy targeted at improving access to grocery stores, access to non-fast food restaurants, income and education may significantly increase healthy eating, but interventions may need to be adapted to specific subpopulations for optimal effectiveness. Note We will release all data aggregated at a zipcode level in order to enable validation, follow-up research, and use by policy makers. Key Points Question How does food consumption and weight status vary with food access, income and education in the United States? Findings In this country-wide observational study of 1,164,926 participants and 2.3 billion food entries, higher access to grocery stores, lower access to fast food, higher income and education were independently associated with higher consumption of fresh fruits and vegetables, lower consumption of fast food and soda, and lower likelihood of being overweight/obese, but these associations varied significantly across Black, Hispanic, and White subpopulations. Meaning Policy targeted at improving food access, income and education may increase healthy eating, but interventions may need to be targeted to specific subpopulations for optimal effectiveness.