Why do many bodybuilders use anabolic steroids instead of actual testosterone?

From what I understand there are many different kinds of anabolic steroids, and I am told that they have different effects in terms of bulking vs cutting and different side effects like pimples, aggression etc.

But ultimately they all work by mimicking testosterone in some way. So why not just take plain old testosterone? There are a few ways I can think of to resolve this question:

  1. my understanding of how anabolic steroids work is overly simplistic and they do not merely mimic testosterone.
  2. they do mimic testosterone but are better at being testosterone than testosterone is
  3. they are just easier to manufacture or traffic or something that makes it easier to obtain illicitly.

Which is it?

Testosterone is one of the anabolic steroids that is frequently prescribed. Other prescribed anabolic steroids are essentially testosterone-like but may have fewer problematic side effects, be stronger or milder in effect, or have longer/shorter half-lives or be better absorbed by injection or topically or orally than testosterone. The prescribing physician will decide which anabolic steroid best serves the patient’s medical need.

Anabolic steroids are prescription drugs and also regulated by the DEA as Schedule IV (4) meds.

Is testosterone the only anabolic steroid produced naturally by the body?

No. A portion of the testosterone is converted into dihydrotestosterone in the body, which is a more potent steroid than plain testosterone (it’s also what causes male pattern balding). I don’t know if there are others.

No, it’s not. The testicles produce mainly testosterone, while the adrenal glands of both sexes (and the ovaries in females) produce a weaker anabolic steroid similar to testosterone called dehydroepiandrosterone, along with some other testosterone variants.

Here’s a nice paper on the pharmacology of anabolic steroids.