When it comes to announcements we could say something like this:Lunch is ready!
Lunch is ready, everyone!
Lunch is ready, come and get it.
As for, casually, stating that you are hungry, it could be "I am starving/I am hungry/I am having/I am feeling pangs of hunger, and you/what about you?"
Okay, now you won´t die of hunger/from hunger anymore! Not for not knowing how to express that in English!