Every boss has a chest with food in it. I combined the grind for this achievement with the 500 deaths.
I would start a run. if the boss isn't within 3 rooms I would instantly return to town, which counts as a death. If it is within 3 rooms I would go to there, and get hit by monsters on the way. I got the idea that when you have damage more pots and crates drop meat. Kill the boss and get 1/2 meat. After that, I would go to the next biome. If the next boss is within 2 rooms, I would again go there and kill it. I didn't do this for the fourth biome just because that boss has too much health that time-wise it isn't worth it.