PROPORTION OF FOOD SUBSTANCES
54. The proportion of food substances necessary for building and repairing the body and for providing it with material necessary for its various functions is a matter to which much discussion has been given. Formerly, it was not understood that the protein should be limited to exactly what the body needed and that its requirements were comparatively low regardless of conditions or exercise. The standard for diet very often allowed as much as 25 per cent. in protein. This percentage has been gradually reduced by the discovery of the actual body needs, so that now it is believed by the most dependable authorities that only about 10 per cent. of the entire day's rations for the adult should be protein. The growing child needs a greater proportion than this because he is building up muscle tissue. The adult whose muscles have been entirely constructed requires protein only for repair, and 10 per cent. of the day's food in protein is sufficient for this. This means that if the total calories for the day are 2,500, only 250 of them need be protein.
55. The remainder of the calories are largely made up by fat and carbohydrate. These, however, need not be in such exact proportion as the protein, for no real danger lies in having either one in a greater amount than the ideal proportion. This is usually three-tenths fat and six-tenths carbohydrate or in a diet of 2,500 calories, 750 fat and 1,500 carbohydrate. The carbohydrate is very much in preponderance because of its easy digestion and assimilation. As may be imagined, it is not a simple matter to figure a diet as closely and carefully as this, and it is only in extreme cases where such planning is necessary.
56. The required amount of protein for the ordinary daily diet can be had with about 3 ounces of meat, together with that which is found in the bread, vegetables, and cereals taken each day. At any rate, the menu should be planned so as to supply a protein dish for at least one meal in the day. The fat is supplied largely by the butter taken and the fat used in the cooking of foods. The carbohydrate is provided by the starch found in cereals, bread, and vegetables and by the sugar contained in fruits, as well as that used in the preparation of various foods and in the sweetening of beverages, cereals, and fruits.
In addition to providing these food substances, each meal should include at least one food, and for dinner preferably two foods, that will supply a large amount of mineral salts, cellulose, and vitamines. As will be remembered, fruits and vegetables are the foods to be used for this purpose.
57. This method of menu planning may seem somewhat difficult at first thought, but in reality it is not different from that which the intelligent housewife follows who attempts to provide her family with a variety of foods and who appreciates the value of that variety. If she plans her menu in this manner, prepares the food so that it will be wholesome, easily digested, and given in the proper proportion, and at the same time watches the weights of the members of the family in the manner suggested, she need have no fear about the general health of her family, for it will be well maintained.