=The Essence of Dietetics.= To the layman the average discussion of food principles is, to say the least, confusing.  Dealing largely, as it does, with unfamiliar terms like carbohydrate and hydrocarbon and calories, it is hard to translate into the terms of the potatoes left over from dinner and the vegetables we can afford to buy.  But the practical deductions are not at all difficult to understand.  Boiled down to their simplest terms, the essential principles may be stated in a few sentences.  The body must secure from the food that we eat, tissue for its cells, energy for immediate use or to be stored for emergency, mineral salts, vitamins, water and a certain bulk from fruits and vegetables,—­this latter to aid in the elimination of waste matter.

Food for repairing bodily tissue is called protein and is secured from meat, eggs, milk, and certain vegetables, notably peas.  Fuel for heat and energy is in two forms—­carbohydrate (starch and sugar) and fat.  We get sugar from sugar-cane and beets, and from syrups, fruit, and honey.  Starch is furnished from flour products—­mainly bread—­from rice, potatoes, macaroni, tapioca, and many vegetables.  Fats come from milk and butter, from nuts, from meat-fat—­bacon, lard and suet—­and from vegetable oils.  The mineral salts are obtained mainly from fruit and vegetables, which also provide certain mysterious vitamins necessary for health, but as yet not well understood.

=What the Market Affords.= The moral from all this is plain.  The human body needs all the foods which are ordinarily served on the table.  Whenever, through fad or through fear, we leave out of our diet any standard food, we are running a risk of cutting the body down on some element which it needs.  They say that variety is the spice of life.  In the matter of food it is more than that, it is the essence of life.  Eat everything that the market affords and you will be sure to be well nourished.  If you leave out meat you will make your body work overtime to secure enough tissue material from other foods.  If you leave out white bread, you will lose one of the greatest sources of energy.  If you leave out tomatoes and cucumbers and strawberries, you deprive your body of the salts and vitamins which are essential.

=A Simple Rule.= There is one point that is good to remember.  The average person needs twice as much starch as he needs of protein and fat together.  That is, if he needs four parts of protein and three of fat, he ought to eat about fourteen parts of starch.  This does not mean that we need to bother ourselves with troublesome tables of what to eat, but only to keep in mind in a general way that we need more bread and potatoes than we do meat and eggs.  The body does not have to rebuild itself every day.  It is probable that a good many people eat too much protein food.  If a man is doing hearty work he must have a good supply of meat, but the average person needs only a moderate amount.  Here again, the habits of the more intelligent families are likely to come pretty near the dictates of science.