Racial/ethnic differences in accuracy of body mass index reporting in a diverse cohort of young adults

Surveillance data describing the weight status of the U.S. population often rely on self-reported height and weight, despite likely differences in reporting accuracy by demographics. Our objective was to determine if there were racial/ethnic differences in accuracy of self-reported body mass index (BMI) in a diverse nationally representative sample of young people. Using data from Wave III (data collected in 2001-2002) of the National Longitudinal Study of Adolescent Health when respondents were aged 18-26, we used gender-stratified multivariable linear regression models to examine the association of race/ethnicity and self-reported BMI controlling for measured BMI while also adjusting for factors known to be associated with weight self-perception. Black males and females (b(Female)=0.45, confidence interval (CI): 0.19, 0.71; b(Male)=0.34, CI: 0.17, 0.51) and Hispanic females (b(Female)=0.30, CI: 0.08, 0.52) and Native American males (b(Native) American=0.87, CI: 0.15, 1.58) reported higher BMIs than their similarly weighted White peers, leading to more accurate BMI reporting in these groups at higher BMIs. Caution should be taken in interpreting results from studies relying on self-reported BMI, as they may exaggerate racial/ethnic differences in weight status.