hyperplasia

[Unnamed]

HGH and IGF cause new cell growth right? does that mean you'll have these new cells forever?

Even if you stop working out?

Or will you lose them eventually?

[Lawrence]

If growth of new cells happens then all these new cells will stay with you. When people stop exercising they don't lose cells.
When you work out these cells grow because of glycogen/fluid retention and amino-acid uptake etc. AAS do the same but on a much greater level.

That's why when you stop steroids/working out or both and then start again some time later, you can return to where you used to be before much more quickly.