Short communication What money can buy: Family income and childhood obesity Young Jo * Department of Economics, University of Illinois at Urbana-Champaign, 214 David Kinley Hall, 1407 W. Gregory, Urbana, IL 61801, United States 1. Introduction This paper investigates the relationship between family income and childhood obesity. The obesity rate in the United States has tripled over the past three decades: Currently, about one third of adults and one fifth of adolescents are obese. A closer look reveals a dispropor- tionately high obesity rate among racial minorities and low-income individuals. 1 Accordingly, public efforts to curb the rising obesity rate are often targeted at low- income families. For instance, an initiative by the U.S. Department of Agriculture, called ‘‘Loving Your Family Feeding Their Future,’’ aims to help low-income women and their children gain greater access to healthy food through nutrition education (USDA, 2012). Examining the relationship between family income and childhood obesity could provide some useful insights into such programs that specifically target low-income families. Focusing on childhood obesity has several benefits over investigating adult obesity. It alleviates the issue of reverse causality inherent in studying the relationship between income and obesity. Although obesity can affect one’s own income among adults (Kelly, 2014), this is not the case for children in most developed countries, where children rarely work. Nevertheless, due to the potential endogene- ity of income, one must take precautions when inferring causality from the relationship between family income and childhood obesity observed here. On the other hand, findings pertaining to childhood obesity can illuminate our Economics and Human Biology 15 (2014) 1–12 A R T I C L E I N F O Article history: Received 6 August 2013 Received in revised form 23 April 2014 Accepted 7 May 2014 Available online 15 May 2014 Keywords: BMI Obesity Children Income A B S T R A C T This paper investigates the relationship between family income and childhood obesity. Using the Early Childhood Longitudinal Study, Kindergarten Class of 1998-99 (ECLS-K), I report three new findings. First, family income and childhood obesity are generally negatively correlated, but for children in very low-income families, they are positively correlated. Second, the negative association between family income and Body Mass Index (BMI) is especially strong and significant among high-BMI children. Third, the difference in obesity rates between children from low- and high-income families increases as children age. This study further investigates potential factors that might contribute to a rapid increase in the obesity rate among low-income children. I find that their faster weight gain, rather than slower height growth, is a greater contributor to the rapid increase in their BMI over time. On the other hand, I also find that the faster weight gain by low-income children cannot be attributed to any single factor, such as participation in school meal programs, parental characteristics, or individual characteristics. These findings add to the current obesity debate by demonstrating that the key to curbing childhood obesity may lie in factors generating different obesity rates across income levels. ß 2014 Elsevier B.V. All rights reserved. * Tel.: þ1 217 333 0120. E-mail address: youngajo@illinois.edu 1 26.8% of Mexican-American adolescent boys are obese, compared to 16.7% of non-Hispanic white boys. 29.2% of non-Hispanic black girls are obese, compared to 14.5% of non-Hispanic white girls (Ogden and Carroll, 2010). Contents lists available at ScienceDirect Economics and Human Biology jo u rn al ho m epag e: h ttp ://ww w.els evier.c o m/lo cat e/ehb http://dx.doi.org/10.1016/j.ehb.2014.05.002 1570-677X/ß 2014 Elsevier B.V. All rights reserved.