Eating only when there is hunger: Hunger can be classified into two types: normal and pathological. Nature gave us natural hunger to keep us active enough to hunt for food. Normal hunger demands food, but not a particular type of food. Anything that is clean and nourishing would suffice. It is powerful enough to make a firm demand for food, but if none is available, it will be content for the time being with a glass of water and will create no significant difficulty.