Food Insecurity, Food Storage, and Obesity
- Presenter:
Chair: Vilma Carande-Kulis; Discussant: TBA Wed June 7, 2006 8:00-9:30 Room 226
Although individuals with poor food security might be expected to have reduced food intake, and therefore a lower likelihood of being overweight, some empirical evidence has indicated that overweight status is actually more prevalent among the food insecure (Townsend et al., 2001; Adams et al., 2003; Sarlio-Lähteenkorva and Lahelma, 2001; Alaimo et al., 2001). As obesity is associated with excessive energy intake, and hunger reflects an inadequate food supply, such observations would appear to be paradoxical (Dietz, 1995). We develop an economic model that shows that this apparently paradoxical result is consistent with rational behavior regarding food availability risk and the effectiveness of food storage options.
We construct a two-period model of utility maximization, in which periods may differ by the availability of food for harvest. The availability of food in the current period is deterministic, whereas the availability of food in the second period is stochastic. Utility in each period is determined by the contemporaneous consumption of food, health status, and time allocated to leisure. Health status is determined, in part, by the stock of internally stored energy. Individuals can either consume food, store food physically (externally) for a future period, or store energy internally (i.e., as body fat). Both forms of storage are subject to depreciation. Individuals seek to maximize utility by allocating time and first period consumption decisions, subject to both time and food availability constraints.
The model suggests that if physical storage is ineffective and the health effect in the second period dominates the consumption effect, then there will be extra consumption in the first period for storage of energy as body fat. The amount of internal storage increases as the variance of food productivity in the second period increases, which is consistent with the empirical observation of a positive relationship between food insecurity and the incidence of overweight. The model further indicates that higher climatic energy needs (e.g., colder climates) and lower efficiency of external food storage will also contribute to increased accumulation of body fat.
The theoretical model is then adapted for use in two simulations. The first simulation indicates that the model also predicts a higher probability of survival of individuals adapting an internal energy storage strategy in the face of increased food insecurity. This suggests that the model applies not just under an assumption of reasoned utility maximization, but also to explanations involving evolutionary behavior. In the second exercise, we adapt the model for use in an empirical simulation involving data from the U.S. Continuing Study of Food Intake in Individuals, showing that the model is consistent with previously noted results regarding the incidence of food insecurity and overweight in those data.
