OBJECTIVES: The objective of this study was to investigate trends in prevalence of high BMI from 2001 to 2008 and examine racial/ethnic disparities. METHODS: Records for a total of 8,283,718 fifth-, seventh-, and ninth-grade students who underwent California's school-based BMI screening between 2001 and 2008 were included. Logistic regression identified trends in prevalence of high BMI (≥ 85th, ≥ 95th,≥ 97th, and ≥ 99th percentiles). RESULTS: For 3 of 4 BMI cut points, prevalence continued to increase for black and American Indian girls through 2008, Hispanic girls plateaued after 2005, non-Hispanic white girls declined to 2001 prevalence levels after peaking in 2005, and Asian girls showed no increases. Non-Hispanic white boys peaked in 2005, then declined to 2001 prevalence levels for all BMI cut points; Hispanic and Asian boys declined after 2005 (for 3 lowest BMI cut points only) but remained above 2001 levels; and American Indian boys peaked later (2007) and declined only for BMI ≥ 95th. No girls and few boys showed a decline after peaking in prevalence of BMI ≥ 99th percentile. In 2008, disparities in prevalence were greatest for BMI ≥ 99th percentile, with prevalence of 4.9% for American Indian girls and 4.6% for black girls versus 1.3% for non-Hispanic white girls. CONCLUSIONS: On the basis of statewide California data, prevalence of high BMI is declining for some groups but has not declined for American Indian and black girls. These trends portend greater disparities over time, particularly in severe obesity. Interventions and policies that are tailored to the highest risk groups should be pursued.
