The Hunger Processor is a machine added by Calculator. It is used to convert food into Hunger Points which can then be inserted in Hunger Modules and Nutrition Modules.
Placing any food item inside the slot with a + will consume it at a rate of 1 item/tick, for each generating Hunger Points equal to the amount of half shanks restored by the food when eaten (for example Apples are worth 4 Hunger Points). Hunger and Nutrition Modules can then be placed in the slot with a - to charge them with the stored Hunger Points at a rate of 4 per tick. These modules can also be placed in the + slot, extracting their Hunger Points to put them inside the machine.