What happens to the population when the world has more population than it can feed? Does it decline slowly? Does Morale suffer as billions starve?
For that matter, how do I get a world with more population than it can feed? These appear to be captured worlds. Do some races have intrinsic fast food bonuses?
Yes, the population slowly declines as millions starve and curse your name
Since approval is morale divided by population, if you're not already at 100% a drop in population can actually increase your approval.
The main way I get a world with more population than it can feed is the build Brindle's Observatory, which gives you a planet with 10 population when the latest caps in Crusade have been 3 or 5. I don't know if that has been fixed in 2.6 or not. There have been bugs in the past where after invading a planet you end up with a huge population, I think those are either known by the devs or maybe fixed by now. Also I haven't played as the Yor in a while, I'm not sure they have a population cap.