system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How come male body builders penises/testicles shrink but female body builders clits grow like penises?

I'm not sure if they're all using the same hormones or steroids or whatever, maybe someone can enlighten me :)
gpt
Because when men use anabolic steroids they are consuming an external testosterone supplement. Because a man is getting testosterone without use of his own testes they shut down production to minimal levels. *Use it or lose it*. So when they cycle off there is a chance your natural test producers won't power up properly and begin adequate production to fend of the female sex hormones floating in your system. (Estrogen is the primary and most well known)

* Penile atrophy, dick shrinkage, isn't common; testicular atrophy, ball shrinkage, is common. 

* bitch tits, gynecomastia, also occurs because of this hormone imbalance.

In women it is somewhat the opposite. They have testosterone flowing in their system, just as men have some estrogen. However they consume a large quantity and it ends leading to male sexual traits to manifest. Such as clitoral enlargement (the clitoris and penis, to generalize greatly, the same thing. A man's penis starts as a clitoris in utero).

Also there is conflicting evidence as to how often these *serious* side-effects occur. Many men who cycle properly do not see any negative effects.