Food Retail Environments in Greater Melbourne 2008-2016: Longitudinal Analysis of Intra-City Variation in Density and Healthiness of Food Outlets.

Obesity prevalence is inequitably distributed across geographic areas. Food environments may contribute to health disparities, yet little is known about how food environments are evolving over time and how this may influence dietary intake and weight. This study aimed to analyse intra-city variation in density and healthiness of food outlets between 2008 and 2016 in Melbourne, Australia. Food outlet data were classified by location, type and healthiness. Local government areas (LGAs) were classified into four groups representing distance from the central business district. Residential population estimates for each LGA were used to calculate the density of food outlets per 10,000 residents. Linear mixed models were fitted to estimate the mean density and ratio of 'healthy' to 'unhealthy' food outlets and food outlet 'types' by LGA group over time. The number of food outlets increased at a faster rate than the residential population, driven by an increasing density of both 'unhealthy' and 'healthy' outlets. Across all years, ratios of 'unhealthy' to 'healthy' outlets were highest in LGAs located in designated Growth Areas. Melbourne's metropolitan food environment is saturated by 'unhealthy' and 'less healthy' food outlets, relative to 'healthy' ones. Melbourne's urban growth areas had the least healthy food environments.