TRT Adds Lean Mass. Training Adds Strength.

Testosterone replacement therapy, or TRT, is prescribed to men whose own testosterone production is too low. Plenty of men assume that bringing testosterone back up will put muscle and strength back on with it. The question is how much replacement alone actually changes, and what it leaves untouched.

A 2024 meta-analysis pooled the placebo-controlled trials of TRT in men with diagnosed low testosterone and looked specifically at muscle, strength and bone. Its answer is useful, as long as you keep straight what was measured and who was studied.

1. What the study looked at

The authors searched three databases for trials published from May 2010 to May 2024. To be included, a study had to:

• Be a randomized trial comparing testosterone with a placebo.
• Enroll men with hypogonadism, meaning low testosterone confirmed by blood tests along with symptoms.
• Treat for at least 24 weeks.

Twelve trials made it in. Treatment ran from 24 weeks to three years, using gels, injections or tablets. The men were mostly middle-aged to elderly, with average ages from about 53 to 77, and the average man in every trial was overweight or obese. Five of the trials studied men with type 2 diabetes, and two focused on frail older men.