Follower food supply?

I check the factions tab and it says “Your followers”. Well I was checking the stats of my followers and it says the food supply is low. How does that work? How do I set up a base and food supply for my ai?

The whole faction system is a relic from Whales Cataclysm that was never completed. I keep hoping that either I will gain enough skill to implement something better, or one of the coders will at some point. A faction system may appear in 0.D experimental.