Improvements to the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) food package guidelines in 2009 appear responsible for reversing the upward trend in obesity prevalence among WIC toddler participants, Madeleine I.G. Daepp, of the Massachusetts Institute of Technology, Cambridge, and her associates reported in.
Using data.gov files from 2008, 2010, 2012, and 2014, Ms. Daepp and her colleagues conducted a quasi-experimental interrupted time series analysis to compare state-level population trends in obesity prevalence among children aged 2-4 years before and after 2009. The goal of the study was to determine whether the WIC package changes had any influence on obesity trends among program participants. Altogether, data from 2,253,471 children in 2000 and 3,152,137 children in 2012 was included in the analysis.
Among the guidelines updated to encourage healthier eating habits were the addition of cash allowances for the purchase of more fruits and vegetables, reduction by half in the allowable portions of juice, reduction in cheese, transition of toddlers aged 2-4 years to low-fat or skim milk, and replacement of refined-grain products with healthier whole grain products.
Across all states included in the study, the authors reported average obesity prevalence of 13% in 2000 and 15% in 2008. Although no change was observed in 2010, by 2014 the obesity prevalence decreased to 14%. Hawaii was excluded because of concerns about data quality.
Ms. Daepp and her associates “estimated a pre-2009 annual trend of a 0.23% increase in childhood obesity prevalence.” After the 2009 package revision, they estimated “a decline in childhood obesity of 0.34% per year [P less than .001].”
This change could not be explained by racial-ethnic makeup or child poverty, changes in maternal prepregnancy body mass indices, or prevalence of macrosomia. Speculating that “unmeasured heterogeneity in WIC populations across states” might explain the difference, the authors also suggested that variance in how effectively the package changes were implemented from state to state could be a factor.
Ms. Daepp and her associates recommended that future studies should focus on evaluating differences in how closely vendors follow the package changes, as well as considering whether any other implementation factors could have an influence on state-by-state trends in childhood obesity.
Study limitations noted included an absence of individual body mass index data and information on changes in energy intake and expenditure.
This study was funded by the National Institutes of Health. Ms. Daepp was supported by a National Science Foundation Graduate Research Fellowship grant. Three coauthors were supported by the JPB Foundation; a fourth was supported by an NIH grant.
SOURCE: Daepp MIG et al. Pediatrics. 2019 Apr 1. .