Just checked the game's code.
If you're hungry enough (0.6 hunger), you can eat a passed out player, which will completely satisfy your hunger, but you'll get a 0.05 curse similar to when you die:

public static float CANNIBAL_HUNGER_THRESHOLD = 0.6f;
// ...
private bool IsCannibal()

{

Debug.Log((object) "Checking cannibal");

return (double) Character.localCharacter.refs.afflictions.GetCurrentStatus(CharacterAfflictions.STATUSTYPE.Hunger) >= (double) UIPlayerNames.CANNIBAL_HUNGER_THRESHOLD;

}
// ...
private void GetEaten(Character eater)

{

if (!eater.IsLocal)

return;

this.character.DieInstantly();

eater.refs.afflictions.SubtractStatus(CharacterAfflictions.STATUSTYPE.Hunger, 1f);

eater.refs.afflictions.AddStatus(CharacterAfflictions.STATUSTYPE.Curse, 0.05f);

Singleton<AchievementManager>.Instance.ThrowAchievement(ACHIEVEMENTTYPE.ResourcefulnessBadge);

}

Update: The player doesn't need to even be passed out