The 300% food tiles are FANTASTIC ways to kill your morale without adding much to your empire. Someone crunched the numbers, and you've better off using markets than doubling your population, since tax revenue is NOT directly proportional population (ie, doubling population does not double tax revenue).

The best use for that many people, actually, is sending them off to war or using them as a meat shield when enemy transports come knocking, and the latter is dangerous since information warfare might do some serious damage.

100%/300% food tiles are just there to mess with new players

Hi chanter! Hope that you are enjoying the game so far though overall.

When DA came out there were some changes made in the morale and population calculations that resulted in high population worlds have extremely low morale. Generally, most "veteran" players either have worlds with 13 billion or 20 billion, depending on the world and its bonuses, as once you get above 20 billion your morale drops off almost exponentially. In case you were wondering this also means in most almost 99% of cases worlds never have more than one farm.

Technically, very high PQ worlds can reach up to 100 Billion (the absolute limit) but its impossible to grow this in game due to the low morale caused by high population (there is no growth at morale levels below 41%) and also the number of tiles that would be have to taken up by farms and morale boosters would make the planet useless when you could get more money out of world with 18 billion and a few stock exchanges that would still have room for labs or factories.

As for economic rating, I don't usually pay much attention to it but I think it looks at RPP (raw purchasing power ie your treasury levels) and income vs expenses.

I hope this helps! Also feel free to ask/post questions to the various players you come across in the GC forums, as almost all are very helpful and courteous and will do all they can to help you. Sometimes even the devs will add what they can

Actually the way it is now is the result of updates that addressed it in the other direction. Back in the early Versions of Dread Lords you could get 100B pop and it still be a viable planet worth something. 1.3 and 1.4 updates put a stop to that. This is a post I made right after 1.4 came out and you can see from the pic it is pretty useless to do except to just say that you did.100B pop.. DA has only added to the limitations of the viability of large populations. You can be at 100% approval at 17B and it will drop straight to the 40% percent range by 19 or 20B. Even though you have no more morale dropoff after 25B, getting there is damn near impossible and definatley not worth the effort gameplay wise.