So what is supposed to happen when the party runs out of rations?

So what is supposed to happen when the party runs out of rations?

So what is supposed to happen when the party runs out of rations? I can’t find any mention in the rulebook; I assume it would mean that they can’t use the “make camp” move until they get more. Should I allow them to hunt small animals to replace their rations? Or should I force them to return to town? Should they take damage every day that they don’t eat?