What he describes isn't any different than what the actors that portray superheroes describe when they get into shooting shape, except they take in thousands of extra calories to build muscle and he's not adding muscle weight, just stripping off anything he can to get more jump height and endurance.
I remember that skaters used to talk about the weight they would have during most of the year vs the weight that they would have to compete at Nationals thru worlds. This was before competing was 6 months of the year and when there wasn't performing opportunities the other 6 months. Sport has changed a lot since those days.
This reminds me of the last Angelina Nikodinov competitive iteration - when she changed her body completely through diet and exercises. We can only hope that the person managing his diet/exercise is sane; after all, he is an adult and can make his own choices regarding those things.