Diet may be divided into three distinct classes - normal, preventive, and curative. In order to understand the application of diet to these several conditions, it is necessary to observe the following rules:

1 Foods must be selected which contain all the desired nutritive elements

2 They must be so combined as to produce chemical harmony, or should at least produce no undesirable chemical action.

3 They must be proportioned so as to level or balance their nutritive elements; that is, to prevent overfeeding on some elements of nourishment, and underfeeding on others

Many fine specimens of men and women have been produced without knowledge of these laws, but in nearly every case it may have been observed that the person was normal as to habits, and temperate in eating, therefore led aright by instinct.

If one lives an active life, spending from three to five hours a day in the open air, the bodv will cast off and burn with oxygen much excess nutrition, and will also convert or appropriate certain nutritive elements to one purpose, which, according to all known chemical laws. Nature intended for another. Much better results, however, will be obtained by giving Nature the right material with which to work, thus pursuing lines of least resistance.

What foods to select, how they should be combined and proportioned, is determined mainly by laws dependent upon the following conditions:

1 Age

2 Temperature of environment time of year or climate

3 Work or activity

(1) As To Age

If we wish the best results we must select and proportion our food according to age, because the growing child or youth needs much structural material -calcium phosphates - with which to build bone, teeth, and cartilage. This is found in cereals and in all starchy foods. The middle-aged person needs but little of these - just enough for repair, and the aged person needs practically none.

While the growing child needs calcium phosphate, he also needs milk and natural sweets, which named in the order of their preference are honey, maple-sugar, dates, figs, and raisins. This does not mean that a generous quantity of vegetables and fruit cannot be taken, but that the articles first mentioned (cereals and starchy foods) should form a conspicuous part of the child's diet.

The adult needs a much less quantity of the heavier starchy foods, because the structural part of the body has been built up. The diet of the adult should consist of vegetables, nuts, and a normal quantity of sweets, a normal quantity of fruits, milk and eggs, with rather a limited amount of cereal or bread products, while the aged, or those having passed sixty, could subsist wholly upon a non-starch diet (non-cereal starch), such as vegetables, milk, nuts, eggs, salads, and fruits, including bananas, which is not a fruit, but a vegetable, and which contains a splendid form of readily soluble starch.

(2) As To Time Of Year

In selecting and proportioning our food we should observe the laws of temperature or time of the year. We should not eat foods of a high caloric or heating value at a time when the sun is giving us this heat direct, thus building a fire inside, while the sun is giving us the same heat outside. The violation of this simple law is the cause of all sunstroke and heat prostrations. On the contrary, if we are going to be exposed to zero weather, we should build a fire inside by eating foods of a high caloric value.

(3) As To Work Or Activity

We should select and proportion our food according to the work we do, because eating is a process of making energy, while work is a process of expending energy, and we should make these two accounts balance.

The Normal Diet

While in some respects each body is a law unto itself, there are a few fundamental rules and laws that apply to all alike. For instance, overeating of starchy foods, in every case, will produce too much uric acid, and finally rheumatism. Also the overeating of sweets and starches will cause the stomach to secrete an over-supply of hydrochloric acid, the effects of which have been discussed in a previous lesson.

Effects of overfeeding on starchy foods and sweets

In laying out the diet, under all conditions, the practitioner must be governed by the above-named rules. He should exercise his judgment, however, in each case according to the prevailing conditions. In prescribing diet it is well to remember that Nature will not tolerate, without protest, any radical change. It often occurs, therefore, that the most correct and thoroughly balanced menu will cause violent physical disturbances which the inexperienced may consider as unfavorable symptoms, but in a majority of cases this is merely the adjusting process, similar to that which occurs when the body is suddenly deprived of narcotics and stimulants after their habitual use.

Temporary disturbances caused by radical changes in diet.

The practitioner should exercise much care in diagnosis. He should study all symptoms and lay out the diet so as to counteract prevailing conditions, and to produce normality.

The tendency of the body, that has been incorrectly fed for many years, to protest against the right kind and the right combinations of food, is often very deceptive. It is not always correct to say that the food did not agree with the stomach, but more correct to say that the different foods did not agree with themselves. The patient should be thoroughly acquainted with these facts, and mentally prepared for some temporary discomforts or physical protest against the new system.

The stomach should agree with natural food.

Infant Feeding

The tremendous mortality among infants and children is due to incorrect feeding more than to all other causes. In the process of reproducing animal life, nearly all abnormal conditions are eliminated. The best that is in the mother is given to the child. The trend of Nature is upward toward higher intelligence and more perfect physical development. For this reason infants are usually healthier than their parents, though millions of babies are rapidly broken in health by improper feeding.