Do Food Stamps Contribute to Obesity in Low-Income Women? Evidence from the National Longitudinal Survey of Youth 1979

Does the Food Stamp Program (FSP), which provides in-kind transfers to low- income Americans, cause female participants to become obese? This question is particularly important because participants are substantially more likely to be obese than are nonparticipants. This paper estimates the effects of food stamp benefits on obesity, overweight and body mass index (BMI) of low-income women. Contrary to previous results, we find little evidence that the FSP causes obesity, overweight or higher BMI. Our analysis differs from previous research in three aspects. First, we exploit a rich longitudinal data set, the National Longitudinal Survey of Youth 1979, to distinguish between full-time and part- time participation. Second, instead of making parametric assumptions on outcomes, we employ a variety of difference-in-difference matching estimators to control for selection bias. Third, we estimate both short-term (one-year participation) and long-term (three-year participation) treatment effects. Empirical results show that after controlling for selection bias and defining the treatment and comparison groups carefully, there is little evidence that food stamps are responsible for higher BMI or obesity in female participants. Our estimates are robust to different definitions of the treatment and comparison groups, and to various matching algorithms.