Sometimes, not allways, my character starve to death when i AFKing. I don't move or jump. I just stand still. The hunger bar drops like crazy. No mobs in my range (I pillared up for testing). Thats annoying because i loosed my good enchanted stuff.

EDIT: Here the evidence, Etho starved to death in his newest Lets Play! https://www.youtube.com/watch?v=tHmlEylrO1E

EDIT 2: I made a time lapse video for you: http://youtu.be/13HD-niEYYA
I eat, stand still, starve and die...

EDIT 3: I just find out, that when the starvation beginns and i log out of the game and log in again, the starvation stopps.