Associations between obesity across the lifespan and adult penis dimensions: a retrospective observational study of Vietnamese men using 3D-modeled prepubertal BMI

Abstract Background Penile size has been a subject of medical and cultural interest. Recent studies mainly focus on correlations between limited adulthood factors and penile parameters. While discussing obesity as a critical factor affecting the penis, only the body mass index (BMI) is considered, ignoring other indices. Furthermore, the impact of childhood obesity on penile dimensions has not been well established, leading to a gap in knowledge. Aim To investigate associations of childhood and adulthood obesity, alongside related anthropometric measures, with penile lengths and girths. Methods This retrospective observational study using convenience sampling included 290 men who presented for reproductive health checks and met the inclusion criteria from June 2023 to July 2024. We reconstructed 3D models based on participants’ childhood photographs to estimate their prepubertal BMI. Other anthropometrics and penile parameters were measured following standardized protocols. Multivariate linear regressions were fitted to evaluate the associations of prepubertal BMI and adulthood body indices with penile parameters, including stretched, pubic-to-tip flaccid, and skin-to-tip flaccid lengths, as well as glans and mid-shaft diameters. Outcomes Penile length measurements, including stretched length, pubic-to-tip length, and skin-to-tip flaccid length, were analyzed in relation to childhood obesity, adulthood obesity, and other anthropometric indices. Results Considering the interaction between childhood and adulthood body compositions, prepubertal obesity was associated with shorter stretched (β = -1.201, P = .05), pubic-to-tip (β = -1.899, P < .01), and skin-to-tip flaccid lengths (β = -1.868, P < .01) in adulthood. Regarding adulthood factors, no significances were detected regarding the present BMI in multivariate linear regressions. There were correlations between waist circumference vs. skin-to-tip flaccid length (β = -0.047, P = .02) and hip circumference vs. pubic-to-tip stretched length (β = 0.047, P = .04). Moreover, prepubertal circumcisions negatively affected the stretched length (β = 0.683, P = .05). Clinical Implications Childhood obesity may have a relationship with penile growth, whereas adulthood obesity primarily affects penile appearance rather than actual size. Strengths and Limitations This study presents a novel approach to assessing the association between childhood obesity and adulthood penile dimensions without long-term follow-ups. Using 3D reconstructions from childhood photos enhances feasibility but may introduce recall bias and potential systematic errors. Conclusion Childhood obesity is associated with penile growth, while adulthood obesity relates to the appearance of the penis rather than the actual size. Thus, there is a need for early interventions to mitigate the potentially long-term effects of childhood obesity on penile development.