Public health concerns over the recent rise in obesity, particularly among U.S. low-income populations, have many policymakers and researchers taking special interest in exploring the effects of participation in the Supplemental Nutrition Assistance Program (SNAP) on obesity and long-term health outcomes. Research studies have reached competing conclusions—in many cases depending on differing study methodologies—with some implicating SNAP participation in the increase of body mass index (BMI) among low-income individuals, and others suggesting that program participation may offer a protective effect on obesity risk. This study examines the effects that childhood SNAP participation has on BMI and time spent obese during both childhood and adulthood, within the context of the neighborhoods in which individuals grow up. The study finds that the neighborhood in which SNAP participants reside has an effect on time spent with obese weight for people in particular age groups.
Self-selection may confound estimates of the effects of both government income-assistance programs and neighborhood conditions. For example, people who live in less-advantaged neighborhoods may be more prone to obesity than those who reside in more-advantaged neighborhoods for reasons that are unobserved or are not captured by the current set of control variables. Likewise, those who use public-assistance income may have family characteristics that make them more prone to particular weight categories, perhaps because of particular family norms. To control for these types of unobservable shared attributes, which do not vary among siblings, the study used sibling fixed effects (FE) models.
FE models are only able to control for unobservable factors that do not vary between the siblings. The study examines whether the sibling sample and the all-child sample look different by observing mean values for key variables and by running ordinary least squares (OLS) regression analysis on both samples and looking for differences in effects. If the effects are similar for these two OLS models, the study can have greater confidence that FE models are not being driven by the sibling restriction.
As hypothesized, and as supported by the literature, children living in more-advantaged neighborhoods were found to spend less time obese as children, although this relationship was most significant for young children ages 2 to 8 and older children ages 14 to 18, with increased effects illustrated in the FE models relative to the OLS models. Similar results were found for urban children for each of the age categories in the FE models. For rural children ages 2 to 8, the study found large coefficient estimates. But large standard errors in the FE models made these coefficients statistically insignificant. Further, for the combined urban-rural samples, the study found that time receiving SNAP benefits during ages 2 to 8 significantly reduced the effects of neighborhood disadvantage on obesity duration during these childhood years. Given that most who receive SNAP benefits for extended periods in childhood live in less-advantaged neighborhoods, this indicates that those enrolled in SNAP for longer durations may be protected from time spent obese during childhood compared to those who do not participate in SNAP while living in less-advantaged neighborhoods. The study also found these interactive effects of neighborhood and time on SNAP for urban children ages 2 to 8 as well, but it did not find these effects for rural children.
While research on rural food access has included differing perspectives on what facets of availability (proximity versus quantity) carry more weight in determining healthy food consumption, the FE models showed no relationship between food store availability and time spent obese, either in childhood or adulthood. Descriptively, the study found that there was less availability of large grocery stores for low-income rural households, including those spending greater than 25 percent of their childhood receiving SNAP benefits, compared to rural households at two times the Federal poverty level. These rural households, in turn, reported less availability than all urban household-income categories. These circumstances had no statistical bearing on weight outcomes for either children or adults.
Results in the adult models mirrored these childhood model findings in that early interventions were found to be the most significant when it came to SNAP participation while living in disadvantaged neighborhoods. For the adult FE models, the study found positive and significant effects for the interaction of time receiving SNAP benefits and neighborhood advantage for children ages 9 to 13 and 14 to 18. Similar significant interaction effects were found in the FE model for children ages 14 to 18 growing up in rural areas. These results indicate that those adolescents who receive SNAP benefits in more-disadvantaged neighborhoods (where the great majority of those enrolled in SNAP for extended periods live) are helped in adulthood to spend less time obese, compared to those who do not receive SNAP benefits while living in less-advantaged neighborhoods or those who receive SNAP benefits while living in more-advantaged neighborhoods.
For the adult model, the study did find some effects of rural residency on obesity. In the FE regressions for 9 to 13 year olds, there was a statistically significant positive relationship between growing up in a rural area and time spent obese as an adult: those who spent all of their childhood in a rural setting spent 15 percent more of their adulthood obese relative to those who spent all of their childhood in urban areas. This finding is consistent with other research focusing on obesity rates of both children and adults from rural areas. Somewhat surprising was that the study found this effect only for this one age group.
The study’s findings suggest that SNAP participation during early childhood and leading up to early adulthood, particularly for those growing up in disadvantaged neighborhoods, has a negative effect on the proportion of childhood and adulthood spent obese. Regardless of the nuanced mechanisms that may potentially explain these results, this study lends support to the larger argument that SNAP is an effective program that helps to reduce food insecurity for 4.7 million U.S. residents, with substantive protective health effects spanning from childhood through adulthood.