I've brought this up with a fat dad and its response was "I'm really fast for a big guy. Plus, I'm super strong."  Same guy who laughed about sitting on his adopted children because he wanted to teach them a lesson in humility when dealing with big people.  Edit:  this was in a restaurant and we were coworkers. There was audio and video surveillance, so I reported him to the police.  Him and his ham wife were in the middle of adopting their 4th child when they were investigated.  Last I heard, the adoption didn't go through.