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

High prevalence of obesity in female Food Stamp Program (FSP) participants has led to the question of whether or not the FSP, which provides in-kind transfers to low-income Americans, causes this serious health problem. 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 partial-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 full year of participation) and long-term (three years of 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. We further examine prior studies and apply their methods to our samples. We find that prior studies significantly overstate the causal relationship between FSP and obesity