Anthropometric Profiling, Somatotype Differentiation, and Methodological Discrepancies in Body Fat Estimation Across Combat Sports: A Comparative Multi-Equation Analysis

Objectives: To evaluate kinanthropometric profiles, somatotypes, Phantom z-scores, and methodological discrepancies among nine body fat percentage (%BF) equations relative to the Katch & McArdle comparator equation across combat sports. Methods: Sixty-seven elite male athletes (Brazilian Jiu-Jitsu: n = 17, Muay Thai: n = 16, Wrestling: n = 16, Taekwondo: n = 18) underwent complete ISAK profiling. Differences across disciplines were assessed via ANOVA, while inter-equation agreement was evaluated using repeated-measures ANOVA, Bland–Altman metrics, Lin’s concordance correlation coefficient (ρc), and principal component analysis (PCA). Results: Striking and grappling disciplines exhibited distinct morphological profiles, with Taekwondo displaying an ecto-mesomorphic habitus versus the endo-mesomorphic profile of grappling combat sports. Substantial systematic differences and proportional biases were observed across %BF equations (p < 0.001). Withers demonstrated the highest agreement with the comparator equation, whereas Durnin & Womersley showed a marked positive bias. PCA ordination (accounting for 71.78% of variance) successfully separated morphological robusticity from linearity. Conclusions: Anthropometric %BF equations produce substantial systematic discrepancies and should not be considered interchangeable when monitoring combat athletes. External validation against an independent criterion method is required before establishing absolute body fat values.