Bruce Randall , old time BB'er, was a bit over 400lbs. Dropped to the 180's. Gained back to 220, or so, and won the Mr Universes title back in early to mid 1950's I believe. No loose skin, small waist and had one of the greatest vacuum poses in BB'ing, past or present.. Don't know how he trained or dieted but was supposed to be super strong in squats and back lifts. Use to go around to high schools and give talks on health, training, etc. Probably in his early 80's by now.
Natural gainers (outstanding genetics for controlling gains or losing muscle mass) seem to have the ability to pretty much weight what they want. Their metabolism is geared to do that. Good Luck to everyone else.