Project:
Growing Up Poor and Weight Problems

Year: 2006

Investigator: Liu, Haiyong

Institution: East Carolina University

Project Contact:
Haiyong Liu
East Carolina University
Department of Economics
Brewster A439, 10th Street
Greenville, NC 27858
Phone: 252-328-1083
E-mail: liuh@ecu.edu

With recent welfare reform, the Food Stamp Program (FSP) and other food and nutrition assistance programs have become the major components of the social safety net for low-income households. The FSP alone serves over 17 million participants, with an average per capita benefit of $75 per month. Nearly 90 percent of FSP recipients live below national poverty lines. The goal of these food and nutrition assistance programs is to mitigate food insecurity and related health problems among vulnerable populations, especially impoverished children.

One measure of health outcomes directly linked to food consumption is obesity. Child obesity has become a very serious public health issue. The percentage of overweight children in elementary school more than tripled from 4 percent in the 1960s to 13 percent in 1999. Overweight children are also at risk for cardiovascular diseases, diabetes, and other serious health problems in childhood as well as negative outcomes on education and earnings.

Beyond genetics, socioeconomic factors contribute to weight conditions.

Given the dramatic trends in the overweight status of the American population in the past few decades, certain socioeconomic factors other than genetics must play a significant role as well. In particular, the looming epidemic of childhood obesity fails to cover the weight/health disparities among children from different socioeconomic groups. The risks of underweight and overweight continue to be the highest among the most impoverished people. Food insecurity, defined as limited access to nutritionally acceptable or safe food, has been attributed as the main cause of the persistent underweight and overweight epidemic among children living in poverty. This study investigates the impact of living in poverty on the risks of childhood overweight and underweight.

The matched mother/child data from the National Longitudinal Survey of Youth (NLSY) are used in this study. This study examines the effects of growing up poor on risks of childhood overweight and underweight, accounting for unobserved heterogeneity that governs both children’s weight and family income. FSP benefits are treated as cash income. The impacts of family income are also estimated on a child’s weight measured by body mass index (BMI) at different points in the conditional distribution of children's weight using a two-stage residual inclusion least absolute deviation approach.

Growing up poor has negative and persistent impacts on children’s weight conditions

Results show that FSP benefits and other welfare programs are likely to mitigate weight problems for children at risk. Without controls for unobserved heterogeneity, the study finds that growing up poor is likely to be associated with reduced risk of being overweight by 4.7 percentage points and increased risk of being underweight by 3.1 percentage points. Both results are statistically significant. Once correcting for unobserved heterogeneity, the results indicate that the estimated effects of poverty exposure on overweight change signs, and the estimates on underweight increase by a factor of two. However, none of these estimates remain statistically significant.

Further, this study finds that the mean effects of family income produced by ordinary least squares fail to characterize the change of BMI distribution induced by family income. Quantile regressions with appropriate controls for unobserved heterogeneity suggest that there are variations in the impacts of poverty exposure along the conditional distribution of child weights. Specifically, this study concludes that children who are at risk of underweight—that is, located at the lower tail of the conditional distribution of BMI because of genetics or other underlying factors—are likely to become underweight as a result of extensive exposure to poverty in early childhood. Similarly, those who are located at the upper tail of the conditional distribution of BMI are subject to increased risk of being overweight when growing up poor. For these children who are at risk of weight problems, as predicted by their family characteristics and other personal traits, receiving FSP benefits will reduce the risks by increasing the disposable family income. Furthermore, the models that use binary indicators of underweight and overweight with controls for unobserved heterogeneity indicate that the mean effects of poverty status on each competing health risk are not statistically different from zero. This finding might help explain the mixed evidence about the impact of FSP participation on the mean risks of weight problems from previous studies.