This theme has been explored via multiple characters in the ever-excellent Hugh Howey’s I, Zombie. Be warned, it’s one of the most horrific zombie books out there.
When it happened to me, I struggled on for ages until I had no choice. Then I went to my doctor, got a heap of blood tests done (practically a whole armful of blood!) and got diagnosed. On meds, all better. No mindless cravings for chocolate. I mean, brains, obviously. Chocolate brains.
What does a vegan zombie say? “Graaaaaiiiiiiiiiinnnnnsss…”