[hare2eternity]

That position does not appear to be supported by clinical evidence. [This study](https://onlinelibrary.wiley.com/doi/10.1111/dar.12433) references several studies that show that taking low (in the context of gym users) doses of steriods and not exercising is more effective at building muscle mass than strength training and not taking steroids.

[cthalupa]

Steroids significantly increase glycogen/water retention in-muscle while on them and for a period of time while coming off of them. This would increase muscle size by the measures noted in Bhasin's study (the big one people reference here), but not increase the amount of actual contractile tissue. There's also a cap there - going up in dosage, going for longer, etc., is not going to continually increase overall muscle size at that rate because you've saturated the stores in the muscle for the glycogen and water.

You will gain some additional contractile tissue doing nothing on gear. The average person, if faced with the two options, will gain more actual contractile tissue opting to lift weights without gear.

You can find huge quantities of people in gyms that are on gear and look like they barely lift.