Body fat indicators perform better than body mass index in identifying abnormal lipid profiles in boys but not in girls.

BACKGROUND: BMI as a body weight indicator, may inadequately represent the biological effect of body fat on lipid profiles. This study aims to assess whether body fat indicators were superior to BMI for recognizing children with dyslipidemia.

METHODS: A nationwide cross-sectional study involving 8944 pediatric participants aged 6-18 years. Measures of fat mass index (FMI), fat mass percentage (FMP), BMI, and four lipid profiles were obtained.

RESULTS: Among boys, the standard multi-linear regression coefficients of FMI for TC, LDL-C, and TG were higher than those of BMI (P < 0.01), but not for HDL-C. Also, the prevalence ratios and area under curves (AUCs) of excess fat classified by FMI for specific abnormal lipid profiles (except for HDL-C) were greater than overweight classified by BMI. The AUCs for detecting children with abnormal TC, LDL-C, and TG of FMI-based excess fat were 3.9%, 5.6%, and 2.8% higher than those of BMI-based overweight, respectively, all P < 0.01. Among girls, the associations of BMI with lipid profiles were substantially similar to FMI. All these results were almost identical when FMP was used instead of FMI.

CONCLUSIONS: DXA measured body fat performs better than BMI in identifying abnormal lipid profiles in boys but not in girls.