Agree with the above. But I don't think it's 100% accurate.  My test levels are about the same off gear as it was 10 years ago.  Maybe cause I don't go over 1000 mg a week or keep cycles to 12 weeks and take plenty of time off.   I think if you are reasonable then you'd be ok, that is just gainin 10-20 pounds...  If you want to be a huge BB, then the above is spot on