How do you practice for hot dog eating contests?

PTSD.

I would imagine that any ill health effects are more likely to result from the food content, and not the (insane) mechanics of consumption. Plus, if we assume that he engages in these events on a rare basis (annually? semi-annually?), the damage may not be that significant.

- Maria over at intueri.org

Apart from obesity, hyperlipidemia and GIT disorders like the ones you have mentioned, I would like to think out that most of the persons even participating in these kinds of competitions must be out of their minds. I could try putting him through a therapist to see what kind of problems he has got.