[ameminator]

Spoiler:

If the first person did not want to eat, he would have answered "No, we are not ready". Him not being ready is enough to negate the whole thing. He doesn't know if the both of them are ready to eat though, because he doesn't know that the second man is ready or not (the second man hasn't revealed his state yet).

Therefore, the second man knows that the first is ready to eat, since the first's answer is "I don't know". Since the second man knows that he himself is ready to eat, he can answer: "we are both ready to eat".