Kingpin also has Sumo and Judo training, IIRC.
He's supposedly ranked with Shang-chi, The Cat, Iron Fist and The Foreigner in martial arts.
I guess he could have a myostatin receptor deficiency, like those babies with big muscles you see.
Some fat isn't a bad thing for a fighter. The Roman Legion and the Gladiators were apparently otter mode, to help with long marches for the legion, and to take a cut for the gladiators.
You know, UFC fighter and sumo wrestler Emmanuel Yarbourough was 6-800 lbs and 6 ft 8.
And apparently Andre could really move fast, but the owners of WWF were obsessed with MASTODONS so they made him fight in slow motion.https://www.youtube.com/watch?v=4O2zl2GcDi4