UCLA

Childhood obesity has been declared the most important public health issue of the 21st century by the World Health Organization. In the United States, the prevalence of obesity among children aged 2-19 years increased three-fold in the past forty years. In recent years, this prevalence has begun to plateau and even decrease among preschool-aged children. For example, in Los Angeles County, obesity prevalence among low-income 4-year old children reached a peak of 22.4% in 2009 and then decreased to 20.3% in 2011. However, a recent report showed that this trend was not experienced uniformly across the county and that obesity rates have not abated in some of the poorest neighborhoods. The goal of this dissertation was to evaluate the contribution of socioeconomic factors, at both household and neighborhood levels, to these varying neighborhood trends in obesity rates among low-income children, ages 2-5 years, in Los Angeles County.

Three separate but related studies were conducted. The first study examined trends in early childhood obesity by household and neighborhood socioeconomic characteristics over 12 years (2003-2014). The study used administrative data from children, ages 2-5 years, participating in the Special Supplemental Nutrition Program for Women, Infants and Children (WIC, the second largest federal nutrition assistance program in the country) in Los Angeles County. While childhood obesity rates increased until approximately 2008, a decreasing trend was observed beginning in 2010/2011, a time that coincides with the end of the 2008/09 economic recession. However, the trends varied by socioeconomic indicator, child’s age, and child’s race/ethnicity with obesity rates among children in some higher SES groups back to 2003 levels, while obesity rates among children in some lower SES groups higher than 2003 levels.

Using the same administrative data, the second study built on the first study by determining whether disparities in early childhood obesity rates by socioeconomic factors have widened in the years following the economic recession when compared to the years prior to the recession. Logistic regression analyses examined whether the time period modified the effect of the socioeconomic factor on early childhood obesity. We found that disparities in early childhood obesity by household-level socioeconomic factors widened for children, although the results varied by child’s age. Disparities in early childhood obesity by household education widened for 2- and 3-year-old children and remained the same for 4-year-old children. Disparities in early childhood obesity by household income widened for 3- and 4-year-old children. The disparities in early childhood obesity by neighborhood-level socioeconomic factors (median household income and share of residents living in unaffordable housing, a major source of family financial strain) did not change between the two time periods.

The third study investigated the contribution of this source of family financial strain – unaffordable housing – to early childhood obesity risk and investigated the potential mechanisms involved. The study used survey data gathered from a random sample of WIC families living in Los Angeles County in 2011 and 2014. Analytic procedures included multivariate linear regression and mediation analyses. Unaffordable housing increased the risk of early childhood obesity and household size was found to modify the effect of unaffordable housing on early childhood obesity. Unaffordable housing, however, was not found to increase adiposity in growing children and mother’s mental health, and child’s diet and sedentary behavior were not found to be mechanisms of this relationship.

Findings of these three studies contribute to the knowledge and understanding of the mechanisms by which socioeconomic factors and financial strain influence growth and obesity risk in young children from lower income communities.