Same deal as darkmatt93: Currently at day 150, 5k in weapons, over 1k in food, about 90 companions, and my health hasn't taken a single dent for a long time. Enemy attacks are infrequent now and I've never come up against any problems with food. I suggest that the enemies start doing A LOT more damage in the later stages to compensate.
Premise reminds me quite about Battleground Legends, but there you would eventually die. Here though, it seems possible to subset for a long time. Perhaps ratchet up the attack frequency as the global human population drops?