Associations between family income and children's physical fitness and obesity in California, 2010-2012

Introduction: Socioeconomic status may influence childhood obesity prevalence and children's fitness level. The purpose of this study was to assess the association between family income and children's physical fitness level and obesity prevalence for 8 racial/ethnic groups. Methods: Data for 1,617,400 fifth-, seventh-, and ninth-grade children who took a physical fitness test from 2010 through 2012 in California were used in this cross-sectional study. Multiple linear and log-binomial regressions were used to test whether low family income (as indicated by eligibility for National School Lunch Program) was associated with physical fitness level or obesity prevalence. Differences were tested by race/ethnicity while adjusting for age and sex. Fitness score was measured on a scale from 0 (least healthy) to 6 (most healthy). Results: Average fitness score was 4.45 (standard deviation, 1.47). Prevalence of obesity was 20.3%, and 56% of children were classified as having lower family income. Lower family income (vs higher) was associated with lower fitness score (coefficient = -0.57; 95% confidence interval [CI], -0.62 to -0.53). Lower-income children had higher prevalence of obesity (relative risk = 1.81; 95% CI, 1.72-1.89) compared with higher-income children. These inverse associations were seen among American Indian, Asian, Pacific Islander, Filipino, Hispanic/Latino, African American, and white children and among children who were identified as being of 2 or more races/ethnicities. Conclusion: Children with lower family incomes tend to have less healthy physical fitness status and have higher risk of obesity than children with higher family incomes. This information can be used to help set policies and provide programs aimed at improving fitness and decreasing obesity risk among low-income children.