This study aimed to establish a hand-to-hand (HH) model for bioelectrical impedance analysis (BIA) fat free mass (FFM) estimation by comparing with a standing position hand-to-foot (HF) BIA model and dual energy X-ray absorptiometry (DXA); we also verified the reliability of the newly developed model. A total of 704 healthy Chinese individuals (403 men and 301 women) participated. FFM (FFM
DXA) reference variables were measured using DXA and segmental BIA. Further, regression analysis, Bland–Altman plots, and cross-validation (2/3 participants as the modeling group, 1/3 as the validation group; three turns were repeated for validation grouping) were conducted to compare tests of agreement with FFM
DXA reference variables. In male participants, the hand-to-hand BIA model estimation equation was calculated as follows: FFM
mHH = 0.537 h
2/Z
HH − 0.126 year + 0.217 weight + 18.235 (
r2 = 0.919, standard estimate of error (SEE) = 2.164 kg,
n = 269). The mean validated correlation coefficients and limits of agreement (LOAs) of the Bland–Altman analysis of the calculated values for FFM
mHH and FFM
DXA were 0.958 and −4.369–4.343 kg, respectively, for hand-to-foot BIA model measurements for men; the FFM (FFM
mHF) and FFM
DXA were 0.958 and −4.356–4.375 kg, respectively. The hand-to-hand BIA model estimating equation for female participants was FFM
FHH = 0.615 h
2/Z
HH − 0.144 year + 0.132 weight + 16.507 (
r2 = 0.870, SEE = 1.884 kg,
n = 201); the three mean validated correlation coefficient and LOA for the hand-to-foot BIA model measurements for female participants (FFM
FHH and FFM
DXA) were 0.929 and −3.880–3.886 kg, respectively. The FFM
HF and FFM
DXA were 0.942 and −3.511–3.489 kg, respectively. The results of both hand-to-hand and hand-to-foot BIA models demonstrated similar reliability, and the hand-to-hand BIA models are practical for assessing FFM.
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