"Dude... Do you have any idea of the amount of crap that goes into those things? There's probably more meat on week old road kill than goes into a burger." At this rate Dean wouldn't last the year because he would have a damn heart attack.
Sam has spent the entire time Dean was out getting them food trying to find some way to break the contract. It's like trying to find a needle in the universe's largest bale of hay. He also ate both complimentary mints off the motel pillows. Sorry, Dean.