I don’t often pay close attention to economy and population density and so on. It’s one of things that I usually hand wave during the planning of a campaign. But The City is a little different. There is no farmland. There are no forests or seas. So what do the inhabitants eat?
For the more evil and monsterously inclined. There’s always the slower less powerful inhabitants.
The City does provide a bit with the Gruel Fountains. Sure it’s pretty much a tasteless porridge but at least it’s food. Of course, the fountains usually come under control of a local gang. That is until they rousted out by the Judges or an angry hungry mob.
Then there’s where most folks get their food. As with most fantasy settings, the solution to any problem is MAGIC! So enter Gastromancers. Magic-Users skilled in the art of summoning food and/or ingredients. Since I haven’t decided what system that I’m going to use I haven’t written up Gastromancers yet. But then I’m also envisioning them as an NPC class. We shall see.