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

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 MyFitnessPal 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 …