Modest ratios of fast food outlets to supermarkets and green grocers are associated with higher body mass index: Longitudinal analysis of a sample of 15,229 Australians aged 45 years and older in the Australian National Liveability Study

Food purchasing decisions are made within the context of the range of options available, yet most epidemiological studies focus upon single outlet types. Ratios of fast food outlets to supermarkets and green grocers were linked to addresses of 15,229 adults in the 45 and Up Study at baseline (2006-2008) and followup (2009-2010). Compared to having no fast food outlet but having healthy food outlets within 3.2 km from home, multilevel growth curves revealed that relative exposure > 25% fast food outlets were associated with 0.36-1.19 kg/m(2) higher BMI (p < 0.05). These associations were consistent as people aged. No associations were observed for food outlets < 0.8 km.