Body fat percentage is associated with pubertal onset in boys and girls

Veronica Groendahl; Holmboe Stine Agergaard; Casper Hagen; Kaspar Sorensen; Jorgen Petersen; Lise Aksglaede; Anders Juul

doi:10.1530/endoabs.110.P681

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Endocrine Abstracts (2025) 110 P681 | DOI: 10.1530/endoabs.110.P681

ECEESPE2025 Poster Presentations MTEabolism, Nutrition and Obesity (125 abstracts)

Body fat percentage is associated with pubertal onset in boys and girls

Veronica Groendahl^{1, 2}, Stine Agergaard Holmboe^{1, 2}, Casper Hagen^{1 2 3}, Kaspar Sørensen^{1, 2}, Jørgen Petersen⁴, Lise Aksglaede^{1, 2} & Anders Juul^{1 2 3}

Author affiliations

¹Copenhagen University Hospital - Rigshospitalet, Department of Growth and Reproduction, Copenhagen, Denmark; ²Copenhagen University Hospital - Rigshospitalet, International Center for Research and Research Training in Endocrine Disruption of Male Reproduction and Child Health (EDMaRC), Copenhagen, Denmark; ³University of Copenhagen, Department of Clinical Medicine, Copenhagen, Denmark; ⁴University of Copenhagen, Department of Biostatistics, Copenhagen, Denmark

JOINT2951

Background: Pubertal timing is influenced by a variety of factors, including body composition. While body mass index (BMI) is commonly used as a marker of adiposity, fat percentage (BF%) may be more strongly associated with pubertal onset in children. Notably, BF% increases with pubertal development, a trend most pronounced in girls. This study aims to evaluate the association between BF% and timing of pubertal onset.

Methods: In total, 1, 007 children and adolescents (59% girls) aged 12. 8 years (5. 9-23. 4) from The COPENHAGEN Puberty Study were included. Besides a clinical examination including pubertal staging, key anthropometric variables, such as BMI, skinfold measurements, and hip/waist ratio, were recorded. BF% was estimated using Slaughter’s equation for skinfold thickness, and pubertal onset was defined by the age of thelarche in girls (>B2) and testis volume >3 ml (>G2) in boys. Sex and age-related SD scores for BF% were calculated using the GAMLSS methods to analyze the relationship between age- and sex adjusted BF% in relation to pubertal timing. Probit regression models were employed to estimate the age of pubertal onset according to differences in BF% quartiles.

Results: BF% and BMI correlated positively with age in girls (spearman rho ρ =0. 46, P < 0. 01 and ρ =0. 67, P < 0. 01, respectively). Similarly in boys, BMI correlated positively with age (ρ =0. 66, P < 0. 01), whereas no correlation was seen for BF% and age in boys. Furthermore, girls generally had higher BF% and hip/waist ratio compared to boys; 19. 8% vs. 16. 9%, P < 0. 01) and 1. 3 vs. 1. 1 in hip/waist ratio (P < 0. 01). Significant lower age of pubertal onset was observed with the highest BF% in boys (mean age Q1: 12. 2 years vs. Q4: 11. 4 years, P < 0. 01) and in girls (mean age Q1: 10. 0 years vs. Q4: 9. 8 years, P < 0. 01) although less pronounced.

Conclusion: In healthy Danish children, a higher BF% was associated with an earlier age of pubertal onset. However, due to the cross-sectional design, causality cannot be determined. It is possible that increased BF% accelerates pubertal onset, or that earlier puberty leads to higher BF%. These findings highlight the important role of body composition in pubertal development and its timing.