User blog comment:Dominic1743/“The Heroes' Journey” Discussion/@comment-108.36.76.116-20200124030226/@comment-98.115.189.149-20200207182912

Dean's appetite may have started off of an ad lib in a scene, but the writers have made use of it for more than just humor. After John made the deal to save Dean, that seems to be when the thing about Dean being empty inside began, and Famine remarked on it, that Dean was so empty and already dead inside. It's why Dean was unaffected by famine. He already lived with an emptiness nothing can fill. When Rowena made her sacrifice to put the souls back in Hell, she did it by means of her own death, because death can contain everything and not be filled up. It also may be part of Dean's connection with the Darkness. In later seasons, they seem to be playing up this aspect of Dean, adding a dream Sam had with Mary talking about Dean always having been hungry, even as a little boy. Remember in Tall Tales, when Dean ate the big ham? His snacking seems to have picked up in this last season.