Don't be fooled by Fury's dad bod, Tyson Fury is blessed with great lower body genetics. He never gains weight on his legs no matter how heavy he gets. His legs always stay nice and lean which is ideal for a boxer. As you probably know, once you gain weight on your legs/thighs it's almost impossible to loose that weight but upper body weight is much easier to lose compared to lower body weight. Most other boxers with his style would have been ruined after so much time off spent putting junk into their body.
Tyson Fury despite appearances never skimps on his roadwork. Even during the long layoff he still put in time on the treadmill.
Yeah compare Fury to that Icelandic strongman Thor. Thor is about 450 pounds and a lot of that weight is in his legs which will be very difficult to lose, but when Fury was 400 pounds most of his weight was in his upper body which meant he could always get back to his normal fleet footed self.
That's because he's on a ton of juice and does 900lbs squats for reps. Thor's actually a naturally lean guy. Used to play basketball before he moved into strongman.
I had always thought a heavyweight was better off with the big tree-trunk legs. A lower center of gravity means you are harder to knock over. Also, a lot of power can be generated in the legs. But since Fury is the greatest and has skinny legs I am probably wrong.
I don't know about him having the best genes at heavyweight he has yet to prove he's the best of his own era so that's quite a statement. But he is indeed a rare specimen. He is very fortunate that his legs don't become bloated and flabby with all that weight he's gained or moving the way he does would be nearly impossible. It's frankly surprising that he has the coordination to fight on the outside and style on guys with his height and weight to begin with. Back in the day a coach would have told him to become a plodding guy with a high guard using a long jab to keep shorter fighters at bay.