A medium sized man at out of door work, fully oxidizes all waste of the system and he requires a higher protein diet,—125 grams. In such event he does not require so much starch and sugar. If on the other hand he were to take but 106.8 grams of protein, as above, he would require more carbohydrates. One working, or exercising in the fresh air, breathes more deeply and oxidizes and eliminates more waste, hence he has a better appetite, which is simply the call of nature for a re-supply of the waste.
In active work, one also liberates more heat, thus more fat, starches, and sugar are required for the re-supply. If one has an excess of starch (glycogen) stored in the liver, or an excess of fat about the tissues, this excess is called upon to supply the heat and energy when the fats and carbohydrates daily consumed are not sufficient for the day’s demand. This is the principle of reduction of flesh.
It is interesting to note that habits of combining foods are unconsciously based upon dietetic principles. Meats rich in protein are served with potatoes, or with rice, both of which are rich in starch. Bread, containing little fat, is served with butter. Beans, containing little fat, are cooked with pork. Starchy foods of all kinds are served with butter or cream. Macaroni, which is rich in starch, makes a well balanced food cooked with cheese.
Pork and beans,
bread and butter,
bread and milk,
chicken and rice,
macaroni and cheese,
poached eggs on toast, and
custards, form balanced dishes.
A knowledge of such combinations is important when one must eat a hasty luncheon and wishes to supply the demands of the body in the least time, giving the least thought to the selection; but hasty luncheons, with the mind concentrated upon other things, are to be strongly condemned. The mind must be relaxed and directed to pleasant themes during a meal or the nerves to the vital organs will be held too tense to permit a free secretion of digestive juices. Chronic indigestion is sure to result from this practice. Dinner, or the hearty meal at night, rather than at noon, is preferable for the business or professional man or woman, because the cares of the day are over and the brain force relaxes. The vital forces are not detracted from the work of digestion.
Experiments in the quantity of food actually required for body needs, made by Prof. R. H. Chittenden of the Sheffield Scientific School, Yale University, have established, beyond doubt, the fact that the average individual consumes very much more food than the system requires. In fact, most tables of food requirements, in previous books on dietetics, have been heavy.
Prof. Chittenden especially established the fact that the average person consumes more protein than is necessary to maintain a nitrogenous balance. It was formerly held that the average daily metabolism and excretion of nitrogen through the kidneys was 16 grams, or about 100 grams of protein or albuminoid food. Prof. Chittenden’s tests, covering a period of six months, show an average daily excretion of 5.86 grams of nitrogen, or a little less than one-third of that formerly accepted as necessary; 5.86 grams of nitrogen corresponds to 36.62 grams of protein or albuminoid food.
Prof. Chittenden’s experiments of the foodstuffs actually required by three groups of men, one group of United States soldiers, a group from the Yale College athletic team, and a group of college professors, all showed that the men retained full strength, with a higher degree of physical and mental efficiency, when the body was not supplied with more protein than was liberated by metabolic activity, and when the quantity of carbonaceous food was regulated to the actual requirement to retain body heat and furnish energy.
It may be well to call attention here to the fact that the food elements, called upon for work, are not from those foods just consumed or digested, but from those eaten a day or two previous, which have been assimilated in the muscular tissues.
In selecting a diet, the individual must be considered as to age, sex and physical condition, also whether active in indoor or outdoor work, and whether he or she breathes deeply, so as to take plenty of fresh air into the lungs.