TIL a study showed that using 600mg/week of testosterone enanthate, an anabolic steroid, can improve lean muscle mass even in men that don't exercise at all. The men who received testosterone but didn't exercise gained more lean muscle muscle mass than the men who exercised and received a placebo.

https://en.wikipedia.org/wiki/Anabolic_steroid#Body_composition_and_strength_improvements

https://www.reddit.com/r/todayilearned/comments/154e38w/til_a_study_showed_that_using_600mgweek_of/