Understanding changes to food environments and diet through trade liberalisation: a study at three scales

Although obesity has been commonly considered an individual problem (including unhealthy behaviours and genetic component), the steep rise of overweight and obesity prevalence in the last three decades holds a strong association with changes in food consumption. The causes of these rapid shifts are related to different processes of globalisation that have shaped food consumption. Several studies have identified trade liberalisation as a significant driver of the rise of obesity. This thesis offers new insights into the associations between trade and investment barriers, food supply chains and health by analysing three geographical scales. The first scale includes a longitudinal assessment of the link between food supply chains and BMI for 145 countries from 1991 to 2013. This scale involved two approaches: the construction of the Food Liberalisation Index (FLix); merging three proxy variables that exemplified food processing, food trade and FDI in the food industry. The relationship between FLix and BMI changes (from 1991 o 2013) was tested through panel regression. The results showed that changes in BMI are positively and significantly associated with FLIx, evidencing the strong association between the opening of trade barriers and BMI increase. Moreover, on a global scale, the group trajectory analysis (from 1991 to 2013) of the three aforementioned processes was carried out. The results from this exploration showed that LMICs have undergone the most acute changes in their food supply chains since the opening of trade barriers. The impact of trade liberalisation was assessed at a local scale by testing the relationship between food-outlet density and deprivation in Mexico City. First, a longitudinal approach explored changes in supermarket density and deprivation from 1990 to 2015, suggesting that the simplest type of supermarket (i.e. bodega) has increased the most in more deprived areas. second, a cross-sectional approach included an exploration of densities of street markets, marketplaces and convenience stores in 2015. The link between food outlet density and household food expenditure was explored. Findings showed that households located in areas with higher densities of supermarkets and convenience stores had higher expenditures on ultra-processed foods. In contrast, households located in areas with high densities of street markets had higher expenses for fresh food. Finally, the thesis included a qualitative exploration individual motivations for selecting a food outlet through a series of go-along interviews. The interviews were comprised of residents of four areas with different levels of deprivation and took place while participants did their food shopping. The analysis of the participants' accounts suggested that motivations for selecting a food outlet depended mostly on cost, quality and convenience. Overall this thesis has contributed to the study of commercial determinants of health by demonstrating the impact of TNCs on the food supply chain at three different scales, and its influence in health and diet. Furthermore, this research provides relevant evidence of the effects of local-food environments in the diet of Mexico City.