This dissertation examines the effects of the Supplemental Nutrition Assistance Program or SNAP, formally known as the Food Stamp Program, on adult weight outcomes. The focus of this work is to uncover the causal effects of the program by applying rigorous identification methods as well as techniques that address data limitations. By understanding the true impact of SNAP on adult obesity, policymakers can pursue appropriate reform measures to avoid unintended consequences of the program while promoting healthy weight outcomes for low-income Americans.
The first essay expands on previous work examining the effects of SNAP participation on adult obesity. Previous research provides some evidence that SNAP participation may have a small positive effect on weight gain for women and no significant effect on men. However, additional research has found that misreporting of SNAP participation in surveys is prevalent and that analysis of program effects when participation is misclassified (misreported) can produce estimates that are biased and misleading. Until now, nearly all studies examining the effects of SNAP on adult obesity have ignored the issue of respondent misreporting. This chapter uses state-level policy variables regarding SNAP administration to instrument for SNAP participation for NLSY79 respondents. To address respondent misreporting I adopt an approach based on parametric methods for misclassified binary dependent variables that produces consistent estimates when using instrumental variables. This study is the first to document the considerable rates of SNAP participation under-reporting in the NLSY79 dataset. In addition, this study finds that, although SNAP participation increases adult BMI and the likelihood of being obese, without correcting for misreporting bias the estimates are overstated by nearly 100 percent.
The second essay uses the same data but applies a different identification strategy to investigate the intensive margin effects of SNAP on adult obesity. To mitigate the severity of endogenous participation and misreporting biases, I employ a strategy that examines only individuals who report participating in SNAP. I utilize a quasi-experimental variation in SNAP amount per adult due to the timing of school eligibility for children. The identification examines the proportion of school-age children in SNAP households who automatically qualify for in-school nutrition assistance programs. A greater proportion of school-age children eligible for free in-school meals proxies for an exogenous increase in the amount of SNAP benefits available per adult. This study finds that increases in SNAP benefits, as proxied by increases in the proportion of school-age children, reduce BMI and the probability of being severely obese for SNAP adults.
Taken together, the results of this dissertation present an intriguing depiction of the effects of SNAP on adult obesity that serves to inform both policymakers and future researchers. On the one hand, the findings indicate that participating in SNAP (extensive margin) leads to weight gain and higher rates of obesity. Yet, on the other hand, increases in the amount of benefits for those who report participating in SNAP (intensive margin) actually leads to reductions in weight and the likelihood of being severely obese
