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. Author manuscript; available in PMC: 2023 Jan 1.
Published in final edited form as: Eur J Clin Nutr. 2021 Mar 26;76(1):111–118. doi: 10.1038/s41430-021-00899-1

Table 2.

Components and calculations for all multi-compartment body composition models.

BV (L) TBW BMC FM (kg) FFM (kg) %Fat
%Fat4C-UWW UWW BIS Mo = total body BMC (kg) × 1.0436 FM = 2.748 (BV) − 0.699 (TBW) + 1.129 (Mo) − 2.051 (BM) FFM = BM–FM %Fat = (FM ÷ BM) × 100
%Fat4C-DXA-Smith-Ryan BVDXA-Smith-Ryan = (FM ÷ 0.84) + (LM ÷ 1.03) + (BMC ÷ 11.63) − 3.12  BIS
%Fat3C-IMAGE BVIMAGE = undisclosed proprietary algorithm  BIS N/A FM (kg) = 2.118 (BV) − 0.780 (TBW) − 1.354 (BM)

BIS bioimpedance spectroscopy, BM body mass, BMC bone mineral content, BV body volume, DXA dual-energy x-ray absorptiometry, FFM fat-free mass, FM fat mass, kg kilograms, L liters, LM lean mass, Mo total body bone mineral, N/A not applicable, TBW total body water, UWW underwater weighing, %Fat relative adiposity, 3C three-compartment, 4C four-compartment.