Cheese is one of the most indigestible of foods. All fried foods are highly indigestible because the fat envelope of the foods has to be melted off before the gastric juice can act on the food substance itself. Pastry is also very indigestible. Of the vegetables, beans, while highly nutritious, are exceedingly difficult of digestion; also boiled cabbage, cauliflower, hot breads, iced drinks, ice-cream, and water-ices.
The Relation of Diet to Various Conditions of Life.—The chief factors influencing bodily needs are age, height, weight, occupation, idiosyncrasies, and atmospheric conditions.
All activity of the human body, whether in the maintenance of its functions or in the performance of labor, is work. These two forms of work may be classified as physiologic and mechanical. Nothing in nutrition is more important than the relation of food to work.
Children are practically in constant motion during their waking hours, and their demand for food energy is from two to three times as much per unit of weight as that for adults.
Sex.—Men and women of the same age and weight, doing the same kind and amount of work, require the same amount of food. The fact that men usually require more food than women is because, as a rule, they weigh more, are more active physically, and perform more external work.
Temperament.—Persons of a nervous type, being more active, use more energy than the phlegmatic, and, therefore, require more food.
Brain Workers.—A man whose work is sedentary and chiefly mental does not need so much food as a man doing muscular work. The amount of carbohydrates required is less, and the amount of fat rather more than for the man doing light muscular work.
Ranke’s diet for the brain worker is: Protein, 100 grams; fats, 100 grams; carbohydrates, 240 grams; giving an energy value of 2310 calories.
The diet should not be bulky, but light and easily digestible. Excess of food and heavy foods are especially bad for brain workers because they produce heaviness, dulness, and drowsiness. Spiced and rich foods upset the alimentary functions, whereby the circulation is flooded with the products of imperfect metabolism to the detriment of the brain.
Trained workmen will do a given amount of labor on less food than untrained, because when persons take up mechanical operations with which they are unfamiliar, or undertake work which exercises a new set of muscles, a unit of work accomplished costs more in food energy than when the muscles have been trained to do a particular thing.