I kept approx. 20lbs of muscle off of my first 12 week cycle,..but, a few other things were vital. I was turning 35, I am a mesomorph body type, I trained hard, ate very well and have naturally big genetics.
I took a short cycle a few weeks after my post cycle therapy (pct) ended, thinking that I would still see gains, even though the guys here all told me it would be a waste of time,..and at the end I had maybe gained a pound or two.
Now nearing the end of another 12 week cycle, training smarter and harder, eating better, I'm up another 15lbs and down in bf%. If I end up keeping 8-10 of those 15lbs I'll be very happy.