Could Obesity Be Contagious?

This paper contributes to explaining the obesity epidemic and finding a potential remedy. We build a theoretical model of food consumption decisions that accounts for social influence. In our model, individuals' rationality is affected by an endogenous social weight norm, which influences their calorie consciousness and perceived survival chances. Individuals are positional, and the degree of positionality describes the extent to which individuals' discounted utility is influenced by the social weight norm. With an endogenous social weight norm reflecting a heavier and heavier average body weight, we show that a high degree of positionality could explain the obesity epidemic. In this environment, a government intervention decreasing energy density is ineffective at reducing steady state body weight. This result could explain why this type of government dietary intervention seem to have had no effect on obesity and suggests that the same type of intervention through the Food Stamps Program would be ineffective on its own. We also find that in the steady state, individuals can be overweight or underweight depending on their degree of positionality relative to the education they receive about the healthy weight. While education programs focusing on either diet or exercise have had moderate success, we show that focusing on healthy weight education could combat social influence and reduce obesity