When we have learned to choose and cook wholesome and appetizing food we have not solved the whole problem of successful feeding. It is possible to make people sick with good food, if it is badly selected and fed at wrong times or in unsuitable amounts. Whether children grow to their full size and strength depends more upon the choice of their food than upon any other one thing. The effect of food is strikingly shown in the case of the white rats in Fig. 74. The two upper ones are the same age. Both had the same mother, lived in the same kind of clean cages, and had plenty of food, but the diet of the upper was good for growth, while that for the middle one was not. It remained perfectly well, but became stunted because of the character of its food. You can see that it resembles the lowest one in the illustration, which is only one fourth as old. In this chapter we shall consider how and when and in what amounts to serve food so that every one may get from it the fullest benefit in both health and happiness.

In Chapter I we learned that the body is a working machine whose first requirement is fuel. Hence the first consideration in the diet is to have the proper amount of fuel for each day, to provide energy for the constant internal work that keeps the body alive, and for the variable external work which may be so light as to consist of the few movements that one makes lying in bed, or sitting quietly; or so hard as to exercise many muscles, as playing tennis, bicycling, or swimming.

Energy requirements of adults.—We have also learned something about the foods which supply this energy; we must now find out how much fuel (in the form of food) it takes to do different amounts of work, just as the owner of an automobile wants to know how much gasoline per mile or per hour is required to run his machine under different conditions. Very careful experiments have been made on many men in different ways to measure their energy output, the most accurate and interesting being those made in a respiration calorimeter, a device so delicate as to be able to measure the extra heat given off when one changes from lying perfectly quiet to sitting up equally still, thus adding the work of holding the upper part of the body upright. A respiration calorimeter large enough to hold a child is shown in Figs. 75 and 76. You can see that it consists of a chamber with thick walls to prevent loss of heat. In Fig. 75 the door is open. When an experiment is going on the door is closed, as in Fig. 76, air being furnished through special tubes. The walls are fitted with delicate thermometers and every device which will help to get the exact amount of heat given off from the body is employed.

Just as it takes more fuel to run a big machine than a little one, so it takes more energy for a large person than a small one; therefore we must know the weight of the one whose food requirements we wish to calculate, as well as the amount of energy required to do different kinds and amounts of work. The following table will help in calculating the approximate fuel requirements of any grown person. The food needs of children and young people under twenty-five will be discussed later.

Light exercise may be understood to include work equivalent to standing and working with the hands, as at a desk in chemistry or cookery; or work involving the feet like walking or running a sewing machine. Many persons, as students, stenographers, seamstresses, bookkeepers, teachers, and tailors do little or no work heavier than this.

Active exercise involves more muscles, as in bicycling compared with walking, or exercise with dumb-bells as compared with typewriting. Carpenters, general houseworkers, and mail carriers do about this grade of work while on duty.

Severe exercise not only involves a good many muscles, but causes enough strain to harden and enlarge them. Bicycling up grade, swimming, and other active sports would be included in this kind of exercise. Lumbermen, excavators, and a few others do even heavier work than this.

Knowing the weight of a grown man or woman, and something of the daily occupation, as in the case of a professional man, we can estimate the probable energy requirement somewhat as follows:

Total Calories per pound for 24 hours, 18; 18 × 154 pounds (the weight of the average man) = 2772, or approximately 2680, Calories per day required. Calculate in this way the energy requirement for various grown persons whom you know.

Energy requirements during growth.—In estimating food requirements of those who are under twenty-five years old, we must bear in mind that the same materials which serve for fuel serve in part for building material. Protein is used for muscle building as well as for supplying energy, and the larger one grows, the greater the reserves of carbohydrate and fat which he can carry. Furthermore, internal activity is greater in the young than the middle aged or very old, and external activity is apt also to be greater. Think, for instance, how much running children do compared with their parents. For all these reasons, we cannot use the table for adults in calculating the energy requirement of young people. In the following table an attempt has been made to take account of their greater needs, but the estimates include only moderate exercise; with hard work more will be required. Notice that the highest allowance per pound of body weight is for the youngest children.

With these two tables for calculating energy requirement we can determine about how much will be needed by each member of the family. A group consisting of a professional man, his wife, and three children under 16 will require about 10,000 Calories per day; a workingman’s family with the same number of children from 12,000 to 14,000, because of the harder work which both parents and possibly the children will do.

Protein requirement.—Since few of our foods consist of a single foodstuff, and we are not likely to make even a single meal on pure fat, or pure protein, or pure carbohydrate alone, we are sure to get some building material in any diet, but we must see to it that we are getting amounts which furnish the best possible conditions for growth and repair.

As we have already seen, nitrogen in the form of protein is necessary to the life of every cell in the body. From protein, too, muscle is built, though we cannot build good muscle merely by feeding protein; a diet moderate in its amount of protein, but with plenty of fuel for healthy exercise is best for muscle building. Under all ordinary conditions, if ten to fifteen Calories in every hundred (10 to 15 per cent of the total Calories) are from protein, the need for this kind of building material will be met. Thus a family requiring 10,000 Calories per day should have from 1000 to 1500 of these as protein Calories. The following table gives the protein Calories in the 100-Calorie portions of some common food materials.

Notice that some foods, like bread, have about the right proportion of protein calories; others, like beef, beans, and peas are very high in protein calories. By combining some foods high in protein with others containing little or none, we can get the right proportion. Thus, 100 Calories of beef combined with 400 each of bread and butter will give 900 Calories of which 114, or 12.7 per cent, are from protein.

It is interesting to work out other combinations which give these good proportions.

Ash requirement.—We are also assured of ash in any ordinary diet, but some attention should be paid to kind and amount, especially as many common foods have lost the parts richest in ash. Patent flour, for instance, made from the inner part of the grain, is not so rich in ash as whole or cracked wheat. Valuable salts are also lost in cooking vegetables when the water in which they were cooked is thrown away. If not desired with the vegetable, this should be saved for gravy or soup. It is not necessary to calculate a definite amount of ash for the diet, if ash-bearing foods are freely used. By reference to the table on page 384 you can see what foods are valuable for supplying the important kinds of ash. Milk is particularly rich in calcium and hence is required when the bones are growing. Eggs have iron and phosphorus in forms well suited to growth. But if eggs are too expensive, the vegetables and fruits generally will supply these same substances.

Diet for growth.—Diets made in the chemical laboratory from mixtures of pure (isolated) protein, fat, carbohydrate, and ash to satisfy all the requirements which we have so far mentioned, do not behave alike when fed to animals. The kind of protein is important as well as the amount. This is shown by experiments in which only one protein is fed at a time. On some, the animals will not thrive. On others, adult animals do very well, but the young ones become stunted like the one shown on page 295. Milk has been found to contain proteins on which young animals can thrive. But even in diets containing the protein from milk, young animals do not develop normally unless the salts of milk are added too. No perfect substitute for milk has ever been found. During the first year of life, a child lives on it almost exclusively; for the first five years it should be considered the most important article in the diet; and throughout the period of growth it should be freely used if children are to become vigorous men and women. If not liked as a beverage, it can be used in cocoa, or cereal coffee, in soups, puddings, and other dishes. Considering what milk may save in the way of more expensive protein foods, such as eggs and meat, and of ash-supplying foods like fruits and vegetables, it is to be regarded as a cheap food. It is possible to get the proper amounts of fuel and protein from white bread and meat, but such a diet is poorly balanced as to ash constituents and especially lacks calcium. It would need to be balanced by adding some fruit or vegetable and even then would not contain as much calcium as is best for growing people. A diet of bread and milk, on the other hand, is so nearly perfectly balanced (supplying fuel, protein, and ash constituents in suitable amounts) that it can be taken exclusively for a long time. Whole wheat bread and milk would be even better, because the whole wheat would supply more iron, in which white bread and milk are not rich. The addition of fruits and vegetables to the bread and milk diet would also be an advantage—partly for the same reason.

Other foods especially valuable for growth are eggs and cereals from whole grains. Children should acquire the habit of eating fruits and green vegetables of all kinds, for when they are older and likely to take less milk and cereals, the fruits and vegetables supply important ash constituents and also help to prevent constipation.

The foods good for children are also good for adults, but the latter can keep their bodies in good repair with less protein and ash in proportion to body weight than are required during growth, and many kinds of protein serve for repair. If there are not enough milk and eggs to go around, adults can take meat, nuts, peas, beans and bread for protein, and trust to these and fruit and vegetables for ash. When the body has been wasted by sickness, however, a return to the foods of growth, especially a diet of milk and eggs, is best for building it up again.

The number of meals in a day.—Knowing how much and what kinds of food are best for each member of the family, we must next find out how to divide the total food for the day into meals. Few of us could take our required fuel in one meal, and if we could, we should probably be hungry before the time for the next meal. Some persons get along very well with two meals a day, but usually their fuel requirement is not high. Most people are more comfortable and more likely to eat a suitable amount in a deliberate fashion if they have three meals a day. When large amounts of fuel have to be taken, four or five meals may be better than three; babies who have to eat in proportion to their size, often 2¹/₂ times as much as their mothers, take 2¹/₂ times as many meals, i.e. 7 or 8 in a day.

The amount of food for each meal.—While the number of meals depends largely on the amount to be eaten in the whole day, and the appetite of the subject, the amount at each meal is most influenced by the nature of the daily occupation. The baby with nothing to do but eat and sleep has meals uniform in kind and amount. The business man who works very hard through the middle of the day, and has not time to take an elaborate meal, nor time to rest after it so that it may digest easily, takes a light luncheon and makes up for it at breakfast and dinner. The outdoor worker who has a long hard day and expends much energy, takes an hour at noon for a substantial dinner, in addition to a hearty breakfast and supper and sometimes a mid-forenoon or mid-afternoon lunch.

Regularity of meals.—More important than the number of meals is regularity as to time of eating and amount of food. Training for the digestive tract is just as important as training the eye or the hand or the brain. We cannot expect good digestions if we have a hearty luncheon to-day, none at all to-morrow, and perhaps a scanty and hasty late one the next day. To take food into the stomach between meals is to demoralize the digestive system. Foods that are excellent as part of a meal provoke headaches and bad complexions, and many symptoms of a protesting stomach, when taken between meals. The younger the person, the more important is regularity. Little children soon suffer if their meals are not “on the minute.” Adults have more difficulty in controlling their time, but if they have to be late to meals, they should be more careful than usual to eat slowly and to choose plain simple food that will digest easily.

Mental attitude toward meals.—Good food may be provided at the proper time and yet the members of a family may fail to keep well and happy unless they come to meals in the right condition. Haste, chill, exhaustion, anxiety, excitement, fretfulness, or anger may interfere with the digestion of the most digestible of meals. Orderly table service, good manners, and cheerful conversation are very important factors in the success of a meal. Peace and joy as well as “calories” are watchwords of good nutrition.

Balanced meals.—Having determined how many meals to serve in the day and what their hours shall be, the next question is how to choose and distribute the constituents of the day’s ration so as to promote digestibility and satisfaction. A meal of pure protein, or fat, or carbohydrate would not be relished, and would have some physiological disadvantages. Digestion is likely to be more complete on a mixed diet. A meal of carbohydrate alone leaves the stomach more quickly than any other kind, and one would feel hungry before the next meal, though one might have had plenty of fuel; a meal of fat alone would leave the stomach very slowly, and one would not have so good an appetite for the next meal; a meal of pure protein would stimulate heat production without any particular advantages, except possibly in very cold weather: it would be decidedly undesirable in hot weather. For these and other reasons it is best to have the different foodstuffs represented in each meal, and to see that no one contains an excess of fat, which tends to retard all digestion. This is what is usually meant by a balanced meal, but it may also include care that about the same proportion of fuel is served at the same meal each day. A meal does not need to be “balanced” in quite the same sense as a day’s ration. The latter must have a definite amount of fuel, a suitable proportion of protein, ash well represented, some food for bulk, the whole selected with regard for the physical condition, tastes, habits, and pocketbooks of those to be fed.

Menus.—Food taken at a stated time constitutes a meal. It may consist of a single food material, as bread, or a single dish, as soup; or it may contain many kinds of food and many dishes. When the day’s ration consists of a single food, there is no trouble in arranging the bill of fare, for all meals are alike. But as soon as we have two foods, we may consider whether they will digest better if eaten together or separately, and which way they will please the palate better. Balanced diets do not necessarily afford attractive menus. Macaroni and oatmeal would make a fairly well balanced meal except as regards ash constituents, but no one would call such a combination pleasing. By the substitution of a little cheese and an orange for the oatmeal, a meal containing about the same fuel value and proportion of protein could be arranged, and it would certainly appeal more to the appetite, and furnish better proportions of ash constituents.

In the construction of the menu for the day or meal, we must consider not only food values and time of day and combinations which shall be digestible, but flavor, color, texture, and temperature of our foods. The study of digestible combinations belongs to the science of nutrition. The harmonious blending of tastes, odors, colors, and the like is an art. Just as there are pleasing combinations of sound, so there are harmonies of flavor; certain dishes seem naturally to “go together.” Habit has a great deal to do with food combinations. A Chinaman would not eat sugar on rice; a Japanese would not cook beans with molasses as the Bostonian does. It is interesting to experiment with new combinations, and study to find out why old ones are pleasing. Why do we like crackers with soup? Butter on bread? Toast with eggs? Peas with lamb chops?

Digestible menus.—Some of our eating habits are worth preserving and cultivating. Fresh fruit for breakfast stimulates the appetite and helps to prevent or overcome constipation. A mild-flavored food like cereal is better relished before we have had meats or other highly flavored food. Soup at the beginning of a meal puts the stomach in better condition to digest the food that follows. Ice cream at the end of a meal is less likely to chill the stomach than at the beginning. Bread and butter afford a good combination of fat and carbohydrate. Crackers help in the breaking up of cheese into particles easy to digest.

Not all of our eating habits are good, however. Griddlecakes, melted butter, and maple sirup taste good, but the cakes make a pasty mass difficult for digestive juices to penetrate. The sirup is likely to ferment, and the butter coating the whole delays digestion greatly. Chicken salad is popular, but combinations of protein with much fat (as in the mayonnaise dressing) always digest very slowly. Simple dishes, without rich sauces or gravies, and not excessively high in fat, are easiest of digestion. Pastries, fried foods, meats with much fat, like pork and sausage, are always more or less difficult and should be attempted only by the strong, or when the body is free from physical or nervous weariness, and not about to undertake mental work.

Attention to the art of menu making not only helps to make the diet easier to digest, but also better balanced. Foods which are similar in color, flavor, and texture, like potatoes and rice, are not artistic in combination, and it is better to substitute for one of them a green vegetable, or meat or butter, in which case we get a better balance, as more ash, protein, or fat would then be included with the starch of the rice or potato.

In making the bill of fare it is a great mistake to consider each meal by itself alone. If we do so, some days are likely to be very high in fuel, while others may be very low. Then, too, the impression left from one meal carries over to the next. We do not care to see on the dinner table the same foods that we saw at luncheon. Our love of variety is one of nature’s ways of seeing to it that we get different kinds of foodstuffs in our diet. Variety stimulates appetite, but this does not mean a great variety at one meal. The truest variety is obtained by a few well-selected dishes at each meal. If we do not exhaust our resources on one meal, we shall be able to have a greater range of foods in the course of a week. A hotel may have fifty or sixty items on its bill of fare, but after a few days one feels as if there were a great sameness, because all of them are impressed on the mind at each meal and every day.

Dietaries.—A dietary, as we shall use the term here,[19] is a statement of the food requirements of a person or group of persons for a day or some other definite length of time, with a selection of foods to satisfy this requirement.

The first part of a family dietary will have to be calculated according to the age, weight, and occupation, as stated on pages 299-303. When complete, it will stand somewhat like this:

In selecting food to satisfy these requirements it is a good plan to make first a list of those foods that need to be included in the day’s dietary, no matter what the particular menu may be. This will include foods for growth where there are children, special dishes needed if any one is sick, and those common foods which we are accustomed to include in every day’s menu, such as bread and butter.

For the family which we are considering, this list will stand somewhat as follows:

This list is to be kept in planning the menu, whose character is further determined by certain dishes which we wish particularly to have included. For instance, we may desire roast beef for dinner. This is a highly flavored meat, and a protein food which will go a long way towards satisfying the adult’s protein needs. Special protein food for breakfast may well be omitted, or take the form of eggs, which are a contrast to the meat in flavor, form, etc. Protein food for luncheon might be fish or some other meat substitute.

Vegetables for dinner should not only harmonize with the meat, but contrast pleasingly with each other. This result is insured by choosing one vegetable from the starchy type, as potatoes or sweet potatoes, and the other vegetable of the green or succulent group, as spinach or asparagus.

Below are two menus, in which have been kept in mind the foods which ought to be included (see page 311) and the artistic arrangement of the day’s meals, with roast beef as the keynote.

By a little calculation from tables giving the 100-Calorie portions of food materials[21] we can find out whether or not we have well-balanced dietaries. Let us take, for example, Menu I, and make a list of the foods required to prepare it for a family of this size.

It is evident that we have enough protein, and as a good share of it is from milk, we know that it will satisfy the children’s requirements in the best possible way. The adults will get theirs largely from the salmon and meat. Comparing this list with our first tentative one, we find that we have used in building up our dietary 21 portions of milk, 5 of cereal, 5 of fruit (not including lemon juice), 4.1 of green vegetable, 8 of meat (including salmon), 18 of bread, and 22 of butter, but no eggs. We have a good representation of the different kinds of foodstuffs, with this exception, and as the boys would need the eggs most, we could put them in for their breakfast, thus adding about 140 total Calories and 50 protein Calories. With this addition we are still slightly deficient in total energy, but to add one or two hundred Calories is a very simple matter. A second serving of potatoes, an extra roll for those whose fuel requirement is highest, or a slightly more liberal use of butter, might well solve the problem. This dietary calculation shows how the menu may help in getting a balanced diet, and how knowledge of food values can be applied as a check on the menu. If we had had fewer dishes in each meal, we should have had to plan to serve larger portions of some or all of them, or to use more freely such staples as bread, butter, and milk.

Each family must find out the kind of menu best suited to its resources. Some typical meal plans suitable for everyday use are given below.

The cost of the dietary.—The types of menu used will depend very largely upon the income of the family. It is comparatively easy to plan attractive bills of fare if one does not have to consider the amount of work involved in preparing them, or the cost of the materials to be used. With knowledge of food values an expensive dietary may be wholesome, but there is great temptation to overeating and waste of food, and it is wise to keep meals simple for the sake of good digestion. Most families have to consider carefully the cost of food if any money is to be saved for books or travel or emergencies. A dietary such as planned on page 313 will probably cost from $1.50 to $2.00 for the day, or from 1¹/₂ to 2 cents per 100 Calories, depending on the locality. Nothing is allowed for waste, which may, if the cook and those who eat the food are not careful, amount to from 10 to 15 per cent of the total cost. It is often estimated that the “average” man will consume about 3000 Calories per day, and the cost may be expressed on this basis as from 45 to 60 cents per man per day; or the dietary spoken of as a 45-cent or 60-cent dietary or whatever the exact cost per 3000 Calories may be. The cost of food for such a family for a year would at this rate be from $550 to $750.

If the allowance for food be placed at 25 per cent of the total income,[22] this dietary would be appropriate for a family with an income of $2200 to $3000 per year. The majority of families have to get along with a lower expenditure for food, yet they want to be well nourished and to enjoy their fare. Fortunately there is no real connection between cost and nutritive value, some of the most nutritious foods being among the cheapest. At the same time, we cannot get wholesome food for nothing. There are very few foods which to-day cost less than ¹/₃ of a cent per 100 Calories, and these are mostly cereal products, such as cornmeal, rolled oats, and flour, or sugars and molasses. These alone will not make a well-balanced, palatable dietary, though they will supply all the fuel needed for an “average” man for a day for ten cents. In many parts of the country to-day it is hardly possible to make a dietary satisfactory week in and week out with an average allowance of less than ³/₄ of a cent per 100 Calories, and even this sum will prove satisfactory only provided there be skill in food preparation as well as food selection. With an allowance of 1 cent per 100 Calories it is possible almost anywhere to make a balanced dietary with some attractiveness in appearance and flavor. In choosing foods with regard to cost a table that shows which are cheap fuel and which dear, is a great help. Prices vary so much with place and season that it is difficult to make one which is very exact, and some rearrangement to suit any particular region may be necessary. The table on page 318 will, however, serve as a guide.

Inspection of this table shows that if we can afford only one cent per 100 Calories for food, we must get a large share from Group I, and a few from Group II; if we wish to use foods in Group III, we shall have to do so sparingly, or offset them with some of the very cheapest in Group I, to keep the average as we wish it.

When we plan an attractive menu and find it is too expensive for us, we may often carry out our plan by substituting cheaper foods of the same sort. Thus in the dietary on page 313 we may substitute as follows:

Bananas for oranges.

Top milk for cream.

Oleomargarine for a part of the butter.

Bean loaf with tomato sauce for creamed salmon and peas.

Stewed apricots for pears.

Rump roast instead of rib roast.

Doing this, omitting the soup and crackers and the salad for dinner, and increasing bread and potatoes, flaked wheat, and other cheaper foods to prevent any deficiency in fuel, we can still prepare palatable and digestible meals with the right food values, and save perhaps 25 per cent on the total cost for the day.

Feeding the sick.—When illness is serious enough for a physician to be consulted, he will give directions concerning the diet, and these should be scrupulously followed. If the case is so severe as to demand a trained nurse, she will have charge of the feeding, under the physician’s guidance. Many times, however, a member of the family is temporarily indisposed and needs food different from the ordinary family bill of fare. It is well to remember that in the first day or two of illness, fasting or taking of very little food does no harm, and may be an excellent help toward recovery, as it gives the digestive tract a chance to rest, if it has been disturbed.

Nevertheless, the internal work of the body goes on, 0.4 Calorie per pound per hour being expended during sleep, and about 0.6 Calorie per pound per hour during waking hours in bed. A person in bed for twenty-four hours will require about 0.5 Calorie per pound per hour to prevent use of body material for fuel. A man of average weight, lying in bed, will thus need about 1850 calories per day. Hence we must see to it, that after a person has been sick for more than a few days (during which he can afford to burn body fat) enough fuel is given to satisfy his energy requirements if he can possibly digest it.

Food for an invalid must always be given in its most digestible forms. Milk is one of the most valuable foods in sickness, not only because it supplies so many body needs, but because it can be used in so many ways,—hot, or cold, flavored or plain, made into junkets or sherbets, combined with eggs in eggnogs and custards, fermented as in kumyss or soured as in buttermilk or zoolak. In some form or other milk can almost always be made digestible. Eggs are also of great value, not only poached or dropped and served on toast, but as dainty omelets, or in beverages, as eggnog, egg lemonade, and orangeade. Mild fruit juices, as orange, grape, or pineapple, are not only refreshing but of considerable fuel value. If there is no fever, chicken, lamb chops, tender broiled steak or roast beef may serve to add variety to the menu. Broths stimulate the appetite and help digestion, though they are of little or no food value themselves. Cereals, eggs, and milk may be added to increase their food value. Cereals in the form of gruels or delicate puddings, as cornstarch blancmange and tapioca cream, are easily digested. Vegetables are best given rather sparingly, and only delicate, mild-flavored ones, such as spinach or asparagus, if digestion is much disturbed. In getting an invalid to take sufficient food, much depends upon the attractiveness of the service. Remember that very little things, like a fingermark on a glass, or coffee spilled into the saucer, may take away appetite and prevent enough food being eaten. Food in small quantities and taken at more frequent intervals than in health helps towards the best results. Knowledge of what particular diet is best in different diseases comes only through careful study of the science of nutrition after much study of chemistry and physiology.

EXERCISES

1. Calculate your own energy requirement.

2. Calculate the energy requirement of your family group.

3. Find the cost for your locality of the dietary arranged from Menu No. 1.

4. Make a dietary yielding 10,000 Calories, from ten to fifteen per cent of which shall be protein calories, from Menu No. II, and calculate its cost.

5. Find out the lowest sum for which a balanced dietary could be obtained in your locality.

6. Revise the dietary from Menu No. I, so that it shall not cost over one cent per hundred Calories.

7. Plan an ideal day’s dietary for yourself.

8. Plan a day’s dietary for an invalid which shall yield 2000 Calories, 300 of which shall be protein Calories.