I'd like to do a thing when a player finishes eating, and this event seems the right one to use. Its only flaw that if the player consumes an item with size 1, the event's stack becomes empty, thus providing no context. Is there a workaround for this? I only came up with checking the duration of "LivingEntityUseItemEvent.Tick", but it's no use if the player stops using item just before tick 1.

Perhaps you could use LivingEntityUseItemEvent.Start to store the type of food being eaten somewhere, and then upon LivingEntityUseItemEvent.Finish reference that stored data to determine what they ate. A HashMap<EntityPlayer, ItemStack> might work, otherwise maybe just write a simple NBT string for the player?

Something like this, this code probably won't work as-is but might get you started...

 

    private Map<EntityPlayer, ItemStack> currentFood = new HashMap<EntityPlayer, ItemStack>();

    @SubscribeEvent
    public void onFoodBeingEaten(LivingEntityUseItemEvent.Start event)
    {
        if (event.getEntity() instanceof EntityPlayer)
        {
            EntityPlayer player = (EntityPlayer)event.getEntity();
            currentFood.put(player, event.getItem());
        }
    }

    @SubscribeEvent
    public void onFoodEaten(LivingEntityUseItemEvent.Finish event)
    {
        if (event.getEntity() instanceof EntityPlayer)
        {
            EntityPlayer player = (EntityPlayer)event.getEntity();
            if (currentFood.containsKey(player))
            {
                ItemStack food = currentFood.remove(player);

                // Do stuff based on food here
            }
        }
    }