User blog comment:Rafe Adler/"Let the Good Times Roll" Discussion/@comment-1031724-20180518164817/@comment-1031724-20180520180513

Castiel made clear he never needed to eat until he lost his grace. The exception was during the Famine episode where Famine affected Jimmy, which affected Castiel, and later 99 Problems where Castiel got drunk when God refused to fight Lucifer (and he was weak from being cut off from Heaven at the time), also Indra is drinking as well due to Heaven about to collapse. Indicating they CAN eat but they don't have to.