Income Disparities in Obesity Trends Among U.S. Adults: An Analysis of the 2011-2014 California Health Interview Survey

The aim of this study was to examine income disparities in obesity trends among California adults. Data were obtained from the 2011−2014 California Health Interview Survey (n = 83,175 adults). Obesity for adults was defined as a body mass index of 30 kg/m2 or above. Family income was categorized as below 100%, 100% to 299%, or 300% and above of the federal poverty level (FPL). Weighted multiple logistic regression analyses were used to examine the association between family income and obesity across survey years after controlling for age, sex, race/ethnicity, smoking status, marital status, education, physical activity, and healthy diet. Obesity prevalence among California adults increased slightly from 25.1% in 2011 to 27.0% in 2014. Compared to 300% FPL or above, <100% FPL and 100−299% FPL were associated with increased odds of obesity, respectively (OR = 1.35, 95% CI = 1.22−1.50, for 100−299% FPL; OR = 1.18, 95% CI = 1.10−1.27, for 300% FPL or above). Each year, lower FPL was associated with higher odds of obesity, except for the year 2014. An inverse association between obesity and family income in each survey year was observed, with the magnitude of the income disparity decreasing from 2011 to 2014. The findings of this study show that family income was negatively associated with obesity among adults in California from 2011−2014, and the magnitude of the income disparity in obesity prevalence decreased over this period. Future studies need to examine potential risk factors associated with the decreasing trend.