THE FOOD-FUEL OF THE BODY-ENGINE WHAT KIND OF FOOD SHOULD WE EAT?
Generally speaking, our Appetites will Guide us.

Our whole body is an ingenious machine for catching food, digesting it, and turning the energy, or fuel value, which it contains, into life, movement, and growth.
Naturally, two things follow: first, that the kind and amount of food which we eat is of great importance; and second, that from the millions of years of experience that the human body has had in trying all sorts of foods, it has adapted itself to certain kinds of food and developed certain likes and dislikes which we call _appetites_.

Those who happened to like unhealthy and unwholesome foods were poisoned, or grew thin and weak and died off, so that we are descended solely from people who had sound and reliable food appetites; and, in the main, what our instincts and appetites tell us about food is to be depended upon.
The main questions which we have to consider are: How much of the different kinds of food it is best for us to eat, and in what proportions we should use them.

Both men and animals, since the world began, have been trying to eat and digest almost everything that they could get into their mouths.

And what we now like and prepare as foods are the things which have stood the test, and proved themselves able to yield strength and nourishment to the body.