I love Zombieland. I happened to watch it last week on FX a couple of times in a row, and I was thinking after the movie that it never really showed us about their eating habits and how they survive during the zombie apocalypse. We know Harrelson's character was obsessed with Twinkies, but he didn't find one until the end, and there was this truck with snowballs in the movie. There was no reference further in the movie if they were surviving on that.

What do all the main characters eat during the course of the movie? 

Judging from the timeline in the movie I wonder if all the grocery stores in towns stopped carrying fresh food after the mutation struck? Anyone have any interesting answers to my question?