Is it possible for heavyweight to go down to middleweight?

[-PBP-]

Off the top of my head Roy Jones went from heavyweight to light heavyweight in one fight and that was one of the reasons for his downfall, IMO.

James Toney has had instances where he would weight over 200 pounds for one fight and go down to 175 for the next. Rumors say he walked around at over 200 pounds even when he fought at 168.