Bimodality of body height and weight in Albanian adolescents at biological maturity

This study reassessed whether the distributions of body height and body weight in Albanian adolescents at biological maturity are best described by unimodal or bimodal models. A total of 2,622 high-school graduates (1,272 males; 1,350 females; age 17.518.5 years) were measured according to IBP standards. Gaussian Mixture Models (GMMs) with one versus two components were fitted to height and weight for the combined sample and separately for males and females. Model selection was based on the Bayesian Information Criterion (BIC). Results showed that height in the combined sample favoured a two-component model, but both sexes individually displayed clearly unimodal distributions, indicating that apparent bimodality in height is driven by sex composition. In contrast, body weight was consistently better described by a two-component model across the total sample as well as within each sex, revealing a predominant normal-weight cluster alongside a smaller higher-weight subgroup. These findings indicate that while body height variation is explained primarily by sexual dimorphism, body weight exhibits genuine within-sex heterogeneity likely linked to lifestyle, environmental, or metabolic influences. The use of GMM combined with BIC offers a rigorous framework for detecting latent subgroup structures, with implications for reference standards and public-health strategies in adolescent populations.