I have always thought that if your body is craving food, and you're eating solid meals and not trying to lose weight, then it is deficient in some way. If the craving is for something specific (dark chocolate, pickles, etc) then it is probably significantly lacking in some vitamin or mineral, and doing its best to tell you so.
If you're constantly hungry, then you are probably missing some nutrients. I would try making a point of eating high-vitamin, high-fat foods. You might add (more) liver to your diet and take a flax seed oil supplement for example, or look at other nutrient-rich foods that you might be missing.
Sometimes when I finish a meal I have a craving for something sweet, which I interpret as the meal being lacking in some nutrient, or too low in fat. Usually 1-2 Tbsp of flax seed oil immediately quells the craving, and is a good way to work the flax seed oil supplement into the day.