Using the furnace and hunger almost go hand in hand when it come to Minecraft. Hunger is only a factor in survival mode, however. When in survival mode, everything in the picture below pops up above your inventory. The part on the left has to do with your armor (top) and health (bottom) and the green bar has to do with XP. The two parts that we focus on when talking about hunger are the part on the right (your hunger bar) and your health (hearts). When in survival mode one needs to eat in order to survive. The hunger bar will gradually deplete over time and the depletion can be sped up by sprinting. When your hunger bar empties, your health begins to chip away and eventually you will die. In order to avoid this one must eat in Minecraft.
Here 4 furnaces are shown, heated up, cooking or making something.
Not only food can be cooked in the furnace, but one can make charcoal, another osurce of fuel, by heating up wood logs.
Other sources of fuel for the furnace include:
Below you can see the different types of foods that can be cooked in a furnace.
Food can be found and made in other ways as well. Below I have listed screenshots of all of the types of foods showing how they are made, where they are found, or how to acquire them. The list also shows the effects on a player when eaten, in respect to the hunger bar.
Not only food can be made in a furnace, but other things as well:
When in survival mode, make sure to keep a steady source of food and use your furnace in order to survive!