A Systematic Review and Meta-analysis of Sex Differences in Subcutaneous and Visceral Abdominal Fat in Children

Context
Sex-based differences in abdominal fat distribution are well documented in adults, with men typically accumulating more visceral adipose tissue (VAT), located around intra-abdominal organs, and women exhibiting higher levels of subcutaneous abdominal adipose tissue (SAAT), distributed in the abdominal subcutaneous layer. However, the developmental onset of these differences remains unclear.

Objective
This systematic review and meta-analysis examined sex-specific VAT and SAAT distribution differences among normal-weight prepubertal children aged 0–10 years.

Data Sources
A systematic search of PubMed, Embase, LILACS, and Web of Science was conducted to identify studies published from the inception of each database through June 2024.

Data Analysis
Standardized mean differences (SMDs) for sex-based differences in VAT and SAAT were calculated using a random-effects model, stratified by age group. The analysis included data from 20 studies. In the overall analysis, prepubertal girls had significantly higher SAAT compared with boys (pooled SMD = 0.23; 95% CI: 0.15–0.32; I2 = 89%). This sex difference became apparent starting in the 3- to 6-year age group (SMD = 0.59; 95% CI: 0.38–0.79; I2 = 80%). In contrast, no significant sex differences in VAT were detected in either the age-stratified analyses or the overall estimate (pooled SMD = 0.09; 95% CI: –0.01 to 0.19; I2 = 91%). However, this finding should be interpreted with caution due to the high degree of heterogeneity observed across studies.

Conclusion
Sex differences in abdominal adiposity appear to emerge early in childhood, with prepubertal girls exhibiting higher SAAT than boys from the age of 3 years. In contrast, the absence of sex-based differences in VAT should be interpreted with caution.