Anabolic steroids

So I've recently started going to the gym, and looking around, there's a fairly standard range of body shapes. Clearly, there's some selection bias, given that people who go to the gym are generally fitter than the average person on the street, but you get the idea.
Then you see people who look like this, who are so far outside the normal range that they can't possibly be achieving those results naturally.
I'm sure that some of them really are doing it through nothing but hard work and a good diet, but steroid abuse exists in a big way, particularly in professional bodybuilding.