To state with exactness what a person must weigh is hardly possible, but average weights have been computed from large age groups of persons who have experienced ordinary good health. The expectancy of life is greatest when these figures prevail. Where one’s weight is only slightly under the average after forty years of age, according to insurance statistics, he is an improved risk. On the other hand in early adult life a weight slightly above the average seems favorable, as if it gave better resistance against certain diseasesone of which is tuberculosis. The toll of this disease is greatest among young persons. A good state of nutrition is important in its prevention. Nothing can be said in favor of the efforts put forth by some girls and young women to attain the envied sylph-like forms of the day, and unwise at-tempts to acquire these have resulted in many instances in serious physical injury and disease.
CAUSES OF UNDERWEIGHT
Underweight indicates an insufficient nutrition of the tissues of the body. It may come as a result of having an insufficient amount of food, or of voluntarily abstaining from it. Poverty and faulty states of hygiene which deplete one’s natural strength and tone may bring it about. At times hereditary tendencies appear to explain it, in part at least. Diseases, particularly those of a chronic nature, are potent in reducing weight. An abnormal functioning of some of the endocrine glands or an inability to digest ordinary good food are both effective causes which may keep one’s weight at a level below the average.
Poverty. Favored as we are in this country we have come to forget that there is often an actual insufficiency of food available to a large number of people. Children, particularly, suffer when the family purse does not permit an adequate food supply. Combined often with poverty is an ignorance of how to feed a family or of what foods to buy to supply its needs. Mere quantity is not always enough; a degree of variety is needed so as to lessen the chance of not supplying some substances essential for natural development. A plate full of food is not a guarantee of an adequate or balanced diet. Often, too, ignorance coupled with some strong indulgence may lead to a virtual starvation where in the light of an intelligent choice a sustaining diet might be provided. The boy whose father is so poor that he can provide only sour milk and potatoes with one or two slices of bread a day, probably is actually fed better than many a child whose father can provide an unlimited dietary.
Dietary Fads. Unfortunately, fads in diet are numerous. They are not always the outgrowth of poverty or ignorance. They may spring from motives of an ulterior type in which notions are taught as guiding principles. Expected financial benefits may lead some men to recommend as food substances, articles which have no proved value. Sectional influence or even religious ideas, especially in the practice of those who do not know the scientific basis of diet, lead often to peculiar fads. Lacking the demonstration of actual clinical advantage, faddists arise at times among men otherwise well informed. This danger may exist even in the views of those who have studied diet only in the laboratory without knowledge of its actual application in the health of human beings.
Irregular Eating Habits. Working through the fore-noon without any breakfast, “nibbling” at all hours, or eating meals at any convenient time may lead to an in-sufficient food intake or an upset of the digestive functions with reduced nutrition. Irregular eating often destroys the natural appetite which should be present at meal time.
Hygiene. Sleep, that “kind nurse,” combines with any reasonable plan of living to make it more effective. With-out it the normal metabolism of the body tissues is disturbed. The overworked victim of the sweat shop presents a picture that is characteristic of the one who has insufficient rest, too much work, and frequently a faulty food supply. With sufficient food, a proper amount of exercise stimulates growth and the development of muscles. A constant strain without carefree relaxation and play tires the nerves, and when their tone is reduced body functions gradually become less and less normal. Other requirements of good hygiene, such as proper ventilation, bathing, and proper clothing, contribute to maintaining an optimum of weight and vigor.
Heredity. Often we find persons who excuse their physical build by placing the responsibility on inheritance. It is true that one’s type of physical form may be the gift of his parents, but careful study of the problem from the medical point of view leads to the conclusion that in the main the actual weight one carries is the result of what he eats, combined with his ability to utilize or appropriate the food eaten. Weight may vary some with the type of physical build, but in the light of present knowledge it should not be looked upon as a fixed state that cannot be regulated. Where one’s weight is definitely below the average, a cause should be sought and if possible corrected.
Disease. All are familiar with the loss of weight incident to acute illness. The human body cannot grow or maintain a normal weight when the poisons of bacteria are being freely spread through its tissues. With chronic infective diseases, such as infectious arthritis, or tuberculosis the common story is one of decreasing weight. Para-sites in the digestive tract which maintain a constant irritation there lead to disturbed digestion and possibly the absorption of toxic products. The loss of undigested food from the bowel, because of the rapid action induced by these organisms is a serious item in the welfare of the patient. Where a long standing or sudden change toward underweight is ‘found search must be made for any organisms that may have established themselves in the body. Also abnormal growths within the body tissues must be sought, particularly in those persons who show a sudden decrease in weight after middle life. Disturbances of function in the blood forming organs also must be thought of. A constant loss of blood, or a failure of the blood forming organs to make enough for the needs of the body usually results in a wasting of tissue.
Perhaps at this point we might mention a peculiar kind of poisoning. Often we hear the remark made that a person is poisoned by his food. In the ordinary sense food does not “poison” any one, except when certain well known bacteria are present in it. However, food does act differently with individuals, and this has come to be spoken of as “allergy”–a term meaning a different reaction. Undoubtedly some of the disturbed intestinal function observed in clinical practice comes because of this type of sensitiveness. One who cannot tolerate foods, loses much valuable nourishment unless he plans care-fully. A fuller discussion of this subject appears in an-other chapter of this book.
Endocrines. In some glandular disturbances abnormal loss of weight is recorded. Increased activity of the thyroid gland increases the rate of oxygen consumption, and the body tissues are oxidized more rapidly than is normal. Again a failure of the pancreas to produce insulin so far as it contributes to causing diabetes mellitus is accompanied by a loss of valuable food in the urine. Re-storing insulin to the system by artificial means which will lead to a proper metabolism of the blood sugar, results in an accompanying recovery in weight.
Imperfect Digestion and Absorption. Probably the greatest single factor in underweight as we commonly see it lies in the inadequate digestion of food. In our patient groups many who have come to look upon their underweight as a state that was determined by inheritance, have been agreeably surprised to find that a well chosen diet of suitable variety and quantity has resulted in acquiring a natural weight.
Where there is a deficiency of digestive juices, probably some of the food is not adequately digested. In the discussion of indigestion we have pointed out wherein shortages in the digestive juices can be estimated. In-ability to digest starch properly may be judged from deficiencies in starch-splitting enzymes. Poor starch digestion frequently is accompanied by much gas and perhaps discomfort. One who has a very low blood sugar shortly after eating may not digest his food well, or may need to distribute his food in a different way through the day. A reduced flow of bile results in poor absorption of digested fats as well as reduced activity in absorbing starches. Proteins have a specific dynamic property which other foods do not have and where they are not adequately digested and absorbed there is a decrease in tone and vigor of muscular and nerve function.
While few of our patients admit it, a large percentage of those who are underweight actually do not have sufficient to eat. For various reasons, some have eaten lightly or with restrictions as to kinds of food used, until they find that eating an average meal is an uncomfortable task. They do not understand that the hollow organs of the human body soon contract when they are not regularly distended to a reasonable degree. These often do well when undertaking to gain weight, by eating oftener than the proverbial three times daily. A nutritious drink, or a small serving of food which contains a liberal portion of calories taken half-way between meals and at bed-time, gives additional nutrition. Such a plan usually should be regarded as temporary. A better understanding of food values will enable one to make substitutions in his diet that will raise its caloric value without materially increasing the quantity of food.
An average weight increases ones sense of well-being, and we believe gives a maximum of usable energy and strength. Resistance to infection is favored by good body tone. The loss of heat from the body is relatively less than in underweight states. The natural deposits of fat within the body help maintain the organs in their normal positions, thus favoring their optimum activity.