Roy Hobbs is always hungry. Like insatiably hungry. The guy's a regular Joey Chestnut. Malamud takes every opportunity to show us that his appetite for food is just a stand in for other hungers.
[Roy's] sensational hitting, pulverizing every kind of pitching, more than made up for his slump. Yet no matter how many bangs he collected, he was ravenously hungry for more and all he could eat besides. The Knights had boarded the train at dinner time but he had stopped off at the station to devour half a dozen franks smothered in sauerkraut […] before his meal on the train, which consisted of two oversize sirloins, at least a dozen rolls, four orders of mashed, and three (some said five) slabs of apple pie. (8.1)
So here's constant physical hunger as a stand in for ambition that can't be satisfied. But wait, there's more. He's also consumed with desire for Memo:
True, there was something about [Memo], like all the food he had lately been eating, that left him, after the having of it, unsatisfied, sometimes with a greater hunger than before. (8.4)
He was gobbling [the food] down and it gave him a feeling of both having something and wanting it the same minute he was having it. And every mouthful seemed to have the effect of increasing his desire for her. (8.133)
Roy's obviously got insatiable appetites for baseball greatness, for Memo, and for steaks. And where does all this hunger get him? After gorging himself at the buffet spread that Memo arranged for the team, he's still hungry. He goes to a restaurant for six hamburgers. After going back to Memo's room he keels over jut as he's about to jump into bed with her. He lands in the hospital having his stomach pumped and delirious with pain. We leave the moral of this story to you, but we think it has something to do with moderation. And staying away from bad news women.