Research

Hormonal

Severe testosterone deficiency in young men causes marked decreases in whole-body protein synthesis and fat-free mass, alongside increased adiposity and decreased muscle strength, independent of changes in systemic GH or IGF-I production.

For young men, maintaining normal testosterone levels is critical for preserving muscle mass and preventing fat gain. If testosterone drops significantly (e.g., due to medical treatment or pathology), you will lose muscle and gain fat even if your growth hormone levels remain normal. This is not just about 'energy balance'; the hormone directly alters how your body processes protein and fat.

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In conclusion, testosterone deficiency in young men is associated with a marked decrease in measures of whole body protein anabolism, decreased strength, decreased fat oxidation, and increased adiposity. These effects of testosterone deficiency are independent of changes in peripheral GH production and IGF-I concentrations...
Nelly Mauras et al. · The Journal of Clinical Endocrinology & Metabolism · 1998

Why this rating

Randomized, controlled, crossover design with rigorous metabolic measurements (isotope tracers, DEXA, dynamometry) on healthy young men.

Source

Testosterone Deficiency in Young Men: Marked Alterations in Whole Body Protein Kinetics, Strength, and Adiposity<sup>1</sup>

Nelly Mauras et al. · The Journal of Clinical Endocrinology & Metabolism · 1998

DOI 10.1210/jcem.83.6.4892

crossover · n=6Cited 370×
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DOI resolved against Crossref · corpus check 2026-06-10

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