From Vox EU (and in today's links), can economic factors explain the rise in obesity?:
Changing economic factors and the rise in obesity: The dramatic increase in obesity has raised the question of whether economic incentives can explain this trend. ...
Of the 27 economic factors, two stand out as having the largest effects. First is the increase in restaurants per capita, which explains 12%, 14%, and 23% of the increases in BMI, obesity, and severe obesity, respectively. Increased availability of restaurant food would likely encourage substitution away from home-cooked meals to relatively unhealthy restaurant meals. Furthermore, fast food is not the lone culprit. When we split the restaurant variable into fast-food and full-service restaurants, we find similar effects for each type.
The second major contributor is the increase in superstores and warehouse clubs per capita, which accounts for 17%, 16%, and 24% of the growth in body mass index, obesity, and severe obesity. The superstore variable combines Walmart Supercenters with the warehouse club chains Costco, Sam’s Club, and BJ’s Wholesale Club. A possible explanation for the impact of these stores on obesity is that they sell food at discounts of around 20% relative to traditional grocers. Alternatively, buying food in bulk at warehouse clubs could contribute to overeating. However, when decomposing the superstore variable, Walmart Supercenters are found to have roughly the same effect as warehouse clubs. Since Walmart Supercenters sell food in traditional package sizes, this reduces the likelihood that bulk buying is a primary explanation.
This analysis suggests that variables related to the costs of eating – particularly Supercenter/warehouse club expansion and increasing numbers of restaurants – are leading drivers of the rise in obesity occurring since the early 1980s. However, the source of these effects remains somewhat uncertain. One possibility, previously discussed, is that they lower food prices, particularly for energy-dense food products and restaurant meals, so that the utility-maximising level of weight has increased. An alternative is that the expansion of Supercenters/warehouse clubs and restaurants has reduced time costs because of the greater availability of such foods. When combined with time-inconsistent preferences (i.e. the inability to follow through on previously made plans) this could lead to weight gains beyond utility-maximising levels. Consistent with this, we find that Supercenter/warehouse club densities are correlated with increases in weight loss attempts, which may reflect eating mistakes.
While restaurants, Supercenters, and warehouse clubs appear to have contributed substantially to the rise in obesity, this does not necessarily mean that they are bad for society. The increased availability and affordability of food brought about by these businesses undoubtedly have substantial benefits for consumers. However, such progress comes at a cost. Future research should investigate the reasons why restaurants and superstores contribute to obesity with the aim of helping policymakers develop appropriately targeted solutions.