Body Composition by Bioimpedance in Transgender Women, Cali, Colombia

Nutritional classification based on body composition in transgender populations poses methodological challenges for health professionals, particularly when sex-based reference criteria are applied. Providing care with a gender-sensitive approach while acknowledging underlying physiological differences remains a complex issue in clinical practice. Therefore, the study aimed to describe differences in body composition classification in transgender women according to the sex selected as reference for analysis.

A descriptive, cross-sectional, exploratory study was conducted using purposive sampling. Twenty-five transgender women aged 23-66 years (mean age: 45.8 years), residents of Cali, Colombia, participated in 2022. Anthropometric measurements included weight, height, waist circumference, and body mass index (BMI). Body composition variables assessed by bioelectrical impedance analysis included lean mass, fat mass, skeletal muscle mass, total body water, visceral fat, bioelectrical impedance vector analysis (BIVA), and somatotype. Each participant was evaluated twice using sex-specific reference criteria (sex assigned at birth and female sex). Statistical analyses included the Wilcoxon signed-rank test, chi-square test, and Fisher's exact test, with a significance level of 5%.

When the same individuals were classified using male and female reference criteria, statistically significant differences were observed in the classification of skeletal muscle mass (p = 0.005), somatotype (p = 0.002), BIVA (p = 0.009), and waist circumference (p = 0.018). No significant differences were observed for BMI or other body composition components.

The findings of this exploratory study highlight biomedical and methodological challenges in the interpretation of body composition in transgender women when sex-based reference criteria are applied. The results underscore the need for cautious interpretation of anthropometric and bioimpedance outcomes and support the importance of further interdisciplinary research to inform the development of appropriate reference frameworks for the nutritional and clinical assessment of transgender populations.