From what I can gather, Kobayashi "trains" by eating raw shredded cabbage and drinking water. The water swells up the cabbage and therefore his stomach.
According to a documentary on competitive eating I saw on the Learning Channel 45+ hot dogs and buns is about fourteen pounds of food. The volume is that of an NBA basketball.
I think I’ll just wait for the July 4th showdown at Nathan’s which should be interesting. Chestnut’s record should light a fire under Kobayashi. He’s got one month to get ready.