Hispanic Adults Demonstrate Higher Fat-Free Mass Density Compared to Cadaver Reference Values: A 4-Compartment Model...

Hispanic individuals represent the fastest-growing U.S. population, yet their body composition profiles remain poorly understood, particularly regarding fat-free mass (FFM) characteristics such as density (D_FFM), hydration (TBW:FFM), bone mineral content (Mo:FFM), and residual mass (R:FFM).

The aim of this research was to measure FFM characteristics in Hispanic adults and compare them against cadaver reference values using a 4-compartment (4C) model.

One-hundred thirty Hispanic adults (60 male, 70 female; aged 28 ± 12, 30 ± 11 years; body mass index 28.28 ± 5.20, 27.90 ± 6.32 kg/m²) participated in data collection. Deuterium oxide, dual energy x-ray absorptiometry, and air displacement plethysmography were used to calculate D_FFM, TBW:FFM, Mo:FFM, and R:FFM. Differences between the Hispanic cohort and cadaver reference values were compared using 1-sample t tests, and between-group differences were analyzed using independent-samples t tests.

Hispanic males (1.103 g/cm³) and females (1.103 g/cm³) showed small effect sizes (ES) in D_FFM compared to cadaver reference values (1.100 g/cm³; both ES = 0.41). Female FFM characteristics (TBW:FFM, Mo:FFM, and R:FFM) demonstrated small to moderate differences from reference values (ES = 0.30-0.59). Compared to cadaver values, males showed moderate differences in TBW:FFM (ES = 0.70) and large differences in Mo:FFM (ES = 1.08) and R:FFM (ES = 0.98). Sex-based comparisons revealed moderate differences in Mo:FFM (ES = 0.78), while all other FFM characteristics exhibited only trivial to small differences (ES = 0.001-0.43).

The small ES for D_FFM and TBW:FFM indicate that densitometry- and bioimpedance-based methods, which rely upon outlined assumptions, may accurately assess body composition in Hispanic adults. Nonetheless, future research should continue evaluating the accuracy of existing body density and total body water-based methods in Hispanic populations to confirm their validity and determine whether refinement or development of population- or sex-specific equations is necessary.