Diet for the Lean.—To a large extent the preceding article will suggest what is suitable here, remembering, however, that regular exercise will be also necessary in order to enable the muscles to increase in size. Green vegetables and fruits should be largely used in addition to the carbonaceous foods, as their food salts (see) are necessary to keep the blood in a condition to allow of proper assimilation. In the case of nervous and consumptive patients, the more digestible forms of fat, such as cream and butter, are to be recommended. Some thin people do not seem able to assimilate much fat. These cases will do better on a smaller quantity. Remember always that it is not what is eaten, but what is assimilated, that goes to increase the weight, therefore if any particular food is found, after a careful trial, to constantly disagree, it must be accepted that for that one at all events, it is not a suitable article of diet.
Diet for Middle Age and the Aged.—In advancing years when less exercise is, as a rule, taken, a restriction in the amount of food consumed is highly desirable. The increasing corpulence, which often begins to show itself from 30 to 40, is far from being a healthy sign; indeed, is often the premonitory symptom of serious disease. It should be remembered that a lessening quantity of food is required from middle life on. This applies to all the elements of food. It is noticeable that a fat person seldom lives to old age, most octogenarians being thin and wiry, and almost all attribute their long life to increasing watchfulness over their health, and largely over what they eat.
When a person is young and taking active exercise, a good deal of surplus food can be worked off, and if the excess be too great, a bilious attack tends to prevent any more being taken, for a time at least.
But as we get on in life, the surplus food, if much is eaten, is deposited in various parts of the body as fatty or gouty accumulations. The liver becomes deranged, and loss of health and strength are at once apparent.
It is then, as Sir Henry Thompson has well pointed out, that the fond but foolish wife often does her husband incalculable harm by her efforts to "keep up his system." She urges and tempts him to take more food, fetching him, between meals, cups of beef-tea, soup, or cocoa, when he really would be greatly the better of total abstinence from all food for several days. What we have said about appetite being the best guide applies to the old especially, and if they could but realize what a very small quantity of food is necessary, they would not be perturbed to find that their appetite guided them to eat very much less than at a younger age.
Milk, which is the ideal food for the very young, is for that reason often undesirable for the old, and it is a great mistake for such to drink much of it with solid food.
Diet for the very aged becomes mainly a question of invalid diet, and it must be remembered that much should be granted to the individual's choice and liking. All foods for the aged should be light and easily digested, and careful attention paid to proper cooking.
A striking example of lost health recovered and life and activity prolonged to a great age, by strict temperance in food, is Cornaro, a Venetian nobleman of the sixteenth century, who lived over 100 years. He says:—"Our kind mother Nature, in order that old men may live to still greater age, has contrived matters so that they should be able to subsist on little, as I do, for large quantities of food cannot be digested by old and feeble stomachs. By always eating little, the stomach, not being much burdened, need not wait long to have an appetite. It is for this reason that dry bread relishes so well with me.... When one arrives at old age, he ought to divide that food of which he was accustomed to make but two meals into four, and as in his youth he made but two collations in a day, he should in his old age make four, provided he lessen the quantity as his years increase. And this is what I do, agreeably to my own experience; therefore my spirits, not oppressed by much food, but barely kept up, are always brisk, especially after eating, nor do I ever find myself the worse for writing immediately after meals, nor is my understanding ever clearer, or am I apt to be drowsy, the food I take being in too small a quantity to send up fumes to the brain. Oh, how advantageous it is for an old man to eat but little! Accordingly, I, who know it, eat but just enough to keep body and soul together."
Digestion.—Digestion is the process whereby the food we eat is turned into material fit to be assimilated by the blood. It begins in the mouth by the mechanical grinding and crushing of the food, and the chemical conversion of the starchy part into sugar, in which form alone it can be assimilated. This conversion is carried out by the saliva. Hence the necessity for thorough mastication, even of sloppy foods that do not seem to require it, and for attention to the teeth in order that they may thoroughly chew. Alcohol and tobacco, as they spoil the saliva, are very unfavourable to digestion, and should always be avoided. Twenty minutes longer to chew one's dinner is worth a whole box of pills, and no one need expect good digestion who neglects thorough chewing and salivation of the food. This may, with advantage, be increased to an extent which most people would think quite absurd. It has been proved that when all food is chewed until completely reduced to a liquid, its nutritive qualities are so increased that about half as much will suffice. This is of immense importance in all cases of weak digestion, or indeed whenever an absence of vigorous health renders the economy of vital energy important.
