The body can only hold on to so many pounds gained at once. (I believe 10 to be the maximum). So you can gain 80 pounds if you like, but you'll still only wind up with 10 -- if you're lucky. Since the body likes to maintain homeostatis, you might hang on to more, but it'll be fat.
Ok, so my cycle where I went from 160 to 200, went down to 190 were mostly "fake" gains, even though messurments at my biopath showed a massgain of more than 2/3?