If you've ever played with Rim of Magic and a mod that adds "positive" health effects that increase hunger rate coughthe mod that shall not be namedcough you may have found that your zombies keep "forgetting" to eat. This fixes that by making them never need to eat, rather than needing to eat very occasionally.
I only tested that the patch works and not if its bugged, so if you run into any problems (eg. with race mods, etc) let me know and I'll take a look at fixing it.
Obviously, this requires Rim of Magic, and only affects pawns with its Undead trait. No other pawn will be affected.