I don't watch those contests, can't... because overeating even a little, (and which I do often), makes me feel worse than most common ailments... like the flu. Just seeing a clip on the news of one of those contests make me cringe.
And like you I don't understand it... how it's possible that is. The physics of it make no sense to me.
and besides the 'cringe' effect it has on me.... it's a dumb thing to do, IMHO.
I have no interest in it whatsoever.