For those of you who have been keeping an eye on the evolving resource mechanics, it's worth noting that the latest stable patch includes some fairly dramatic changes to the way food production works.
Nearly all colonist types now produce 0.5 food, however, only if they're on a planet with an environment that they like. For most species, this means that Island, Garden, and Paradise worlds consume half as much food as they used to.
I've also tweaked the farm production rules. There's now a significantly larger "active" production component to farms, and farms now take 2 colonists to fully staff. The size of the active component increases with tech, and production bonuses from tech are bigger for farms on high fertility worlds than low fertility worlds.
This means that, at the start of the game, a farm on an Arid world and Garden world will produce the same amount of food (4 each), but with tier 3 farms, the arid farm will only produce 8 food, while the garden farm will produce 11.
I'm expecting most players to ignore the details of the numbers -- but, the high-level consequences should be pretty intuitive. If you colonize lots of hostile-environment worlds, food supply is more likely to be a problem. And if you tech up in farming, you can turn some of your garden/island/paradise worlds into real "bread baskets", capable of both feeding their own populations, and exporting a significant surplus.