Relative fat mass (RFM) is linked to testosterone deficiency in adult males.

Purpose: Relative fat mass (RFM) is a novel obesity assessment metric, and we aim to explore the relationship between RFM and testosterone deficiency in US adult males.

Methods: This study included data from adult males aged 20-59 years from the NHANES 2013-2014 and 2015-2016 cycles. RFM was calculated using a linear equation based on height and waist circumference (WC). Testosterone deficiency was defined as a total serum testosterone level of less than 300 ng/dL. Logistic regression, subgroup analysis, and smooth curve fitting were employed to explore the relationship between RFM and the risk of testosterone deficiency.

Results: This study included 3243 participants, with 771 diagnosed with testosterone deficiency. Testosterone-deficient individuals exhibited significantly higher RFM levels compared to those with normal testosterone levels (31.23 ± 0.23 vs. 27.16 ± 0.19, P < 0.001). After adjusting for confounding variables, a positive correlation emerged between RFM and testosterone deficiency (OR = 1.16, 95 %CI = 1.11-1.22, P < 0.001). Smooth curve fitting further supported this relationship. Subgroup analysis did not identify any special populations. Receiver operating curve (ROC) analysis results indicated that RFM showed greater effectiveness compared to body mass index (BMI) and WC.

Conclusions: Elevated RFM levels were found to be linked to the risk of testosterone deficiency. Further studies on RFM hold promise to evaluate and address testosterone deficiency.