Correlations of Anthropometric Measurements With Body Fat Percentage, Fat Mass, and Fat Mass Index in School-Age Children

Background: Childhood obesity is a growing public health issue globally, including in India. Anthropometric measures such as body mass index (BMI), waist circumference, and skinfold thickness are commonly used to estimate body fat percentage (BF%), but their correlations with fat mass (FM) and fat mass index (FMI) are less emphasized. This study aimed to explore the relationships between anthropometric measurements and body fat indicators (BF%, FM, and FMI) in school-age children and obtain prediction equations for FM and FMI.

Methods: This observational cross-sectional study included 250 children (125 boys, 125 girls) aged six to 15 years. Anthropometric measures (BMI, waist circumference, skinfold thickness, etc.) and body composition (via bioelectrical impedance analysis) were collected. Pearson's correlation and multiple regression analyses were used to assess the relationships between anthropometric measurements and body fat indicators and to develop prediction models.

Results: BMI, waist circumference, and triceps skinfold thickness showed strong correlations with FM (r = 0.74, r = 0.73, r = 0.61, respectively) and FMI (Pearson's correlation coefficient (r) = 0.76, r = 0.64, r = 0.57, respectively), while the waist-to-height ratio (r = 0.08) and the arm-to-height ratio (r = 0.12) were poorly correlated with BF%. Our prediction equations for FM and FMI provided better predictive values (R² = 0.75 and 0.69, respectively) than BF% (coefficient of determination (R²) = 0.35).

Conclusion: FM and FMI showed stronger correlations with anthropometric measurements than BF%. The waist-to-height ratio and the arm-to-height ratio had small correlations with all three body fat indicators. The prediction equation for FM and FMI outperformed the one for BF%, underscoring their potential utility in assessing adiposity in school-age children.