PD596 - COMPARATIVE VALIDITY OF FAT MASS AND FAT-FREE MASS INDICES AGAINST BODY FAT PERCENTAGE IN ADULT INDIAN WOMEN BEYOND BODY MASS INDEX

PD596

COMPARATIVE VALIDITY OF FAT MASS AND FAT-FREE MASS INDICES AGAINST BODY FAT PERCENTAGE IN ADULT INDIAN WOMEN BEYOND BODY MASS INDEX

S. A. Varma^1,*, D. C. Patel², M. V. Patil³

¹Nutrition, BelleVue MultiSpeciality Hospital, ²Nutrition and Dietetics, D Y Patil School of Medicine, DY Patil University, Mumbai, ³Nutrition, Ashakiran JHC hospital, Pune, India

Rationale: BMI, though widely used, does not distinguish fat from lean mass, risking misclassification. This study evaluated validity of Fat Mass Index (FMI) and Fat-Free Mass Index (FFMI) against body fat percentage (BF%) in adult Indian women.

Methods: Multicentric cross-sectional study, 680 women (25-45 years) from outpatient departments of multi-speciality hospitals in Mumbai, Navi Mumbai, and Pune were assessed (April-November 2024). Anthropometry and body composition (BF%, FMI, FFMI) were measured via bioelectrical impedance analysis. Associations with BF% were examined using Pearson’s correlation, variance explained via linear regression, and ROC analysis to derive BMI cut-offs for BF% ≥30% and ≥35%.

Results: FMI showed the strongest correlation with BF% (r=0.965), followed by BMI (r=0.951) and FFMI (r=0.848) (all p<0.0001). BF% explained 93.1% of variance in FMI, 90.4% in BMI, and 71.9% in FFMI. ROC analysis identified BMI cut-offs of 20.3 kg/m² (AUC=0.979) and 23.7 kg/m² (AUC=0.982) for BF% ≥30% and ≥35%, respectively, suggesting underestimation of adiposity using conventional thresholds.

Index    r with BF%    Variance (%)         Inference

FMI        0.965               93.1                  Highest validity
BMI        0.951               90.4                 Good, but indirect
FFMI      0.848               71.9                  Lower discriminatory value
                                                                 

Conclusion: Fat Mass Index exhibited superior validity for adiposity assessment. While BMI remains a practical screening tool, reliance on it alone may underestimate obesity burden; encompassing body composition indices may enhance clinical and public health evaluation. 

Disclosure of Interest: None declared