I tend to keep long term saves, while the food system seems to be designed with a single "playthrough" in mind. For instance, you can't really "earn" more money by simply playing the game, and the only way to get food is to buy it or get very lucky finding a food cache out in the wild, or very small amounts when you ingest semen. The fact that there's still a talent to boost your scavenging chance, when you can no longer scavenge (aside from when you have completely 100% run out of food, and even then you usually only get enough for a few more turns, and risk a bad end if you fail), leads me to believe that the mechanic isn't in it's "final form" yet anyway. If enemies dropped a token amount of gold, so that when you got to town you could stock up (assuming they even have enough food in stock!), that would go a long way to fixing thing.
That and having extra party members shouldn't make you take more food per turn, but it does. I invited them to join me, I didn't offer to provide them food forever! But I'm damned sure going to take them with me, so cheating it is.