The effect of the 2009 WIC food package change on childhood obesity varies by gender and initial weight status in Los Angeles County.

Abstract

To assess whether the effect of the 2009 women, infants, and children (WIC) food package change on obesity outcomes varies by initial weight status and gender. Using 2003 to 2016 data from Los Angeles County, we compared growth trajectories and obesity at age 4years among children exposed to WIC after the food package change (n=53075) vs children exposed before (n=53075). Analyses were stratified by gender and initial weight status: low weight-for-height z-score (WHZ≤25th percentile), average WHZ (25th<WHZ<75th percentile), and high WHZ (WHZ≥75th percentile). Within strata, children exposed to the new vs old packages were matched on sociodemographic characteristics and compared using growth models and Poisson regression. Mean WHZ trajectories for children exposed to the new food package, compared with the old, tended to be lower during ages 1 to 5years. For boys, the new food package was associated with 10% to 14% lower obesity risk at age 4years in all initial weight status strata. For girls, the new package was associated with 16% lower obesity risk at age 4years only for those with average WHZ at baseline. The change in WIC food packages appears to be associated with obesity prevention benefits for boys regardless of initial weight status, with more limited benefits for girls.