A sweeping review of 12 international cohort studies shows that heavier boys, especially those carrying excess weight after age six, reach key puberty milestones sooner, reshaping how parents and clinicians understand the biological impact of childhood adiposity.
Study: The relationship between childhood obesity and male puberty development: a systematic review and meta-analysis. Image credit: New Africa/Shutterstock.com
In a recent study published in Frontiers in Endocrinology, a group of researchers quantified the influence of childhood adiposity, defined as overweight and obesity, on the timing and characteristics of male pubertal development across global cohort studies.
Rising global obesity reshapes boys’ development patterns
One in five school-age boys now lives with excess body fat. This has led to questions about the influence of higher weight on the progression of puberty. Puberty in boys is driven by the hypothalamic-pituitary-gonadal (HPG) axis and brings testicular enlargement, pubic hair, rapid height gain, voice change, and first ejaculation.
Early or late timing can affect self-esteem, school relationships, and long-term cardiometabolic health. Around the world, childhood obesity continues to surge, pushed by energy-rich diets, sedentary lifestyles, and social inequality. Evidence links higher weight to earlier puberty in girls, but these findings are conflicting in boys, so further research is needed.
Meta-analysis reviews global cohorts of boys’ growth
The investigators conducted a systematic review and meta-analysis, registered on the International Prospective Register of Systematic Reviews (PROSPERO). They reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines.
Studies were identified in PubMed, Embase, and Web of Science from inception to July 2025. Eligible designs included cohort studies comparing overweight or obese boys with normal-weight boys. Overweight and obesity were defined using World Health Organization (WHO) age- and sex-specific body mass index (BMI) percentiles or related adiposity measures.
Pubertal development was assessed using Tanner staging, testicular volume, pubic hair development, peak height velocity (PHV), first ejaculation, and voice change, where available. Reviewers independently screened records, extracted data, and rated study quality with the Newcastle-Ottawa Scale (NOS).
Effect estimates reported as risk ratio (RR), hazard ratio (HR), or odds ratio (OR) were harmonized as RRs with 95 % confidence intervals (CI). Fixed effect or random effects models were selected based on heterogeneity systematically assessed by chi-square testing and the I2 statistic. Sensitivity, subgroup, and publication bias analyses were performed, and overall certainty of evidence for each outcome was graded with the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.
Overweight boys consistently show earlier testicular growth
Across 12 prospective cohorts from Asia, Europe, North America, and South America, the synthesis included large population-based samples, with individual cohorts ranging from hundreds to tens of thousands of boys followed from early childhood into adolescence.
Compared with their normal-weight peers, overweight boys had a significantly higher risk of early testicular enlargement, with a pooled RR of 1.38 and 95 % CI 1.15 to 1.65. Obese boys showed a similar pattern, with an RR of 1.43 and 95 % CI 1.18 to 1.73. When overweight and obesity were combined as a single higher adiposity category, the risk of early testicular enlargement remained elevated, though more modestly.
Timing measures told a similar story. On average, overweight boys reached Tanner Stage 2 testicular volume about a quarter of a year earlier than normal-weight boys. For obese boys, the point estimate suggested an earlier onset as well, but the CIs included no difference, reflecting fewer data and greater variability. Abdominal obesity, captured by waist circumference or body fat percentage, was also significant; boys with central fat accumulation had an approximately 1.7-fold higher risk of early testicular enlargement than boys without this pattern.
Pubic hair, another visible milestone, also appeared earlier in heavier boys. Overweight boys had a 24 % higher risk of early pubic hair development, and obese boys had a 42 % higher risk compared with normal-weight peers. In contrast, age at PHV, the fastest phase of the adolescent growth spurt, did not differ significantly between obese and normal-weight boys, suggesting that obesity shifts some but not all aspects of the pubertal timetable.
Subgroup analyses helped explain differences across studies. Associations between overweight and early testicular enlargement were stronger in the Asia Pacific region than in the United States, and stronger when weight was measured after the age of six, suggesting that school-age weight trajectories may be more significant than measurements in toddlerhood.
Individual cohorts also linked higher prepubertal BMI to slightly earlier first ejaculation and earlier voice change, reinforcing the pattern of advanced sexual maturation among heavier boys. Sensitivity analyses revealed that no single cohort drove the findings, and funnel plots, along with Egger testing, suggested minimal publication bias.
Overall, the GRADE assessment rated the evidence for early testicular enlargement as high quality and the evidence for other outcomes as moderate, supporting a credible link between higher adiposity and earlier male puberty milestones globally for boys.
Excess weight emerges as a biological puberty trigger
This study indicates that childhood overweight and obesity are not just cosmetic issues but meaningful biological stressors that shift several markers of male puberty earlier. Overweight and obese boys, especially those with greater central fat, are more likely to show early testicular enlargement and pubic hair development, even though the pace of the growth spurt may be unchanged.
For families, clinicians, and schools, this means weight management in middle childhood could influence both metabolic health and the timing of puberty. Larger, diverse cohorts and mechanistic studies are needed to refine risk estimates and guide tailored prevention strategies for boys worldwide.
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