In working out the dietary according to the new principles, a number of factors besides the character of the food and the idiosyncrasies of the individual should he taken into consideration. "The season of the year, the climate, the degree of activity, the state of health, all present special conditions which demand particular dietetic treatment," says Professor Chittenden. "In hot summer weather, for example, there is plainly less need for food than in the cold winter season, especially for fat with its high calorific value. During the cold part of the year, the lower temperature of the surrounding air, with the tendency toward greater muscular activity, calls for more extensive chemical decomposition in order to meet the demand for heat and the energy of muscular contraction. There is perhaps no special reason for any material change in the amount of proteid food consumed in the two seasons, except in so far as it seems desirable at times to take advantage of the well known stimulating properties of proteid to whip up the general metabolism of the body, in harmony with the principle that all metabolic processes may need spurring to meet the demands of a greatly lowered temperature in the surrounding air.

"Fuel value, however, should be increased somewhat during the winter months in our climate. Fat promises the largest amount of energy, but there is more of a tendency to store excess of fat than of carbohydrate, hence the latter foods have certain advantages as a source of the additional energy needed during cold weather. In warm weather it should be our aim to diminish unnecessary heat production as much as possible, though it must be remembered that the body calls for an adequate amount of food. Lighter foods, however, may be advantageously employed, such as fruits, vegetables, fresh fish, etc. Fats and fat meats especially are to be avoided, not only because there is no specific need for them, but particularly on account of the greater sensitiveness of the gastro-intestinal tract during the hot seasons of the year, that is liable to result in a disturbance whenever undue quantity of rich food or heavy food is taken. Further, in hot summer weather we may advantageously live more largely on foods served cold, and thereby avoid the heat ordinarily introduced into the body by hot fluids and solids. .........

"In old age, there is naturally a slowing down of the metabolic processes, and both nitrogen equilibrium and body equilibrium can be satisfactorily maintained by a relatively small intake of food and with gain to the body; but there is every reason to believe that economy in proteid food can be more advantageously adopted than economy in non-nitrogenous foodstuffs."31

In conclusion it should be emphasized that there is nothing in the new conception of diet that requires a man to do or not to do anything that sets him apart from his fellows and marks him out as a crank. Mankind has probably risen to the commanding position which it occupies to-day because it has always been able to subsist on all classes of food. Therefore, it seems hardly rational for man to cut himself off, absolutely and uncompromisingly, from any one of the great food staples of the race. There is no article of diet - with the possible exception of alcohol - that, taken in moderation, can be a source of danger or disease. The method which accords best with the truths of science as well as with the promptings of common sense, is to eat temperately of the foods that individual experience have proved to be most pleasing to the appetite and acceptable to the system. As Professor Chittenden puts it:

"The master words which promise help in the carrying out of an intelligent plan of living are moderation and simplicity; moderation in the amount of food consumed daily, simplicity in the character of the dietary, in harmony with the old saying that man eats to live and not lives to eat. In so doing there is promise of health, strength, and longevity, with increased efficiency, as the reward of obedience to Nature's laws."32

31 Chittenden: "Nutrition of Man," pp. 996-997.

32Chittenden: "Nutrition of Man," p. 301.