In Detail
Testosterone is one of the primary drivers of muscle protein synthesis. Restoring deficient levels supports both the building of new muscle in response to training and the preservation of existing muscle in men who are losing it with age, illness, or weight loss.
The effect is dose-dependent and training-dependent. Testosterone alone, without resistance training, produces modest changes in body composition. Combined with consistent resistance training and adequate protein (roughly 0.8 to 1 gram per pound of target body weight per day), the combination yields meaningfully better outcomes than either alone.
For men over 40, preserving muscle is not vanity — it is one of the strongest predictors of metabolic health, fall risk, and longevity. Treating low testosterone is part of that strategy.