User blog comment:Xilinoc/Realistic One Piece/@comment-24769684-20150525202904/@comment-2125188-20150528102321

He was supposed to be there for a month, but only 9 days had passed at the time. It says on the wiki and chapter itself.

For some people it is possible for someone to die from hunger in about a week, but given Zoro's physical shape it would've been highly unlikely.