The basis of most steroid cycles is sust / testosterone (same thing) which is basically loading your body with extra hormone. Testosterone is mainly responsible for the extra muscle of men over women and users can have up to 10x (though don't quote me, not my strong area) the natural level. I suspect it might well be more. There are various other steroids out there which perform other functions like raising your metabolism and burning fat e.g. tren or clenbuterol but mainly its based around raised test levels. Clever people will go through post cycle therapy to protect their body and try and hold onto the gains they made while hormonally enhanced.