A careful medical examination ways includes a record of the patient's weight and, particularly, information as to whether he has been gaining or losing weight rapidly. Doctors have tabulations which show the average weight for people according to their age, sex, height, and body build. Some people are tall and thin with light bones and light muscles. Others may be stocky, short, muscular.

Water constitutes about seventy per cent of the body weight. About one fifth of all the water is outside the individual cells. This is found in the blood, the spinal fluid, the lymph and a small amount between the cells. The remainder of the body weight is in solid structures like the bones; most of the minerals of the body are in the bones. Sugars are stored in the body-principally in the liver and muscles-as glycogen.

Fat is an inactive material deposited around the body in storage depots. Proteins are the chief building elements of the cells. The body needs four grams of water for each gram of protein. The amount of calories taken by the body to maintain its weight depends on the rate at which the body uses up material, and this in turn is related to the amount of activity. Growth requires increased calories. When inadequate amounts of calories are taken into the body the deficit is supplied by using up material from the tissues. The fat is drawn upon, but also the carbohydrates. When both fat and carbohydrate are utilized, the protein is taken up. This means the breakdown of some functioning cells.

Conditions in which there is interference with the usual elimination of sodium cause increased water retention and gain in weight. Examples are heart failure, toxemia of pregnancy, hardening or cirrhosis of the liver and congestive heart failure. Elimination of water is improved by stopping salt, improving heart action, or by drugs which increase the action of the kidneys.

Increase of fluid in the body occurs when the protein is inadequate. In such cases restoration for protein results in elimination of water. Excess of sweating or severe diarrhea also draw water from the body and thus lower weight.

The weight of the body is also related to the action of the thyroid gland, which has a part in determining the basal metabolism. Fever will increase the metabolic rate. Excess action of the thyroid will also give a rate over on the plus side whereas deficient action of the thyroid moves the rate to the minus side.

Eating is regulated by many factors. Appetite may be part of a habit of large eating. Many families put overemphasis on eating. Grandmothers offer food as cures for most family disturbances. Sometimes a person who has had an active life with heavy eating changes to a sedentary life. The eating habits persist and he puts on weight. Some people eat as a substitute for satisfactions that they do not obtain through other emotional sources. Incidentally, alcoholics frequently drink because they escape other demands in this way. An unusual cause of excessive eating is over activity of the pancreas gland in developing insulin. An injury to the brain which affects certain portions of a part of the brain called the hypothalamus may be associated with the development of a voracious appetite. But by far the vast majority of cases of obesity are due to taking too much food in relation to the metabolism and activity of the body.

Loss of weight can be produced by lowering the calorie intake to less than the body requirement. Starvation may result from lack of appetite, which is called "anorexia." Loss of appetite occurs in acute and chronic infections, in certain forms of cancer and glandular diseases. Loss of appetite may be wholly psychological or mental, producing a condition called anorexia nervosa.

Nutritional Disorders

Great numbers of people believe that most diseases come from wrong food. As a result innumerable dietary fads and fancies attract them. Really, the body is a chemical plant which manufactures some of the substances it absolutely must have to survive. Fundamental mineral substances cannot be manufactured by the body. Vitamins cannot be manufactured by the body and must be taken in food or otherwise, since the body depends on them for health and growth.

Dietary deficiencies naturally occur most often among people who get insufficient food but also among those who get the wrong foods. The most common dietary disorder is overweight or obesity.

At present the vitamins which human beings must have for health include vitamin A and carotene, which is its precursor; thiamin and riboflavin and niacin which are parts of the vitamin B complex; also vitamin C and vitamin D, vitamin K, folic acid and vitamin B12.

The Food and Nutrition Board of the National Research Council has prepared a table of recommended daily dietary allowances for persons of both sexes, various ages, during pregnancy and nursing, for sedentary persons, physically active persons, and for heavy workers. Calorie intake varies from 2000 daily for sedentary women to 4500 daily for male heavy workers. Women's needs increase during pregnancy and nursing of their babies. Children's needs vary with their ages, weight, sex and activity also.

The lists of substances to be assured in the diet include good proteins, calcium, iron, the vitamins. Also needs must be met for water, salt, iodine, phosphorus, copper, vitamin K and folic acid. Simple tables can be secured from the United States Public Health Service and other governmental agencies.

Undernutrition

Throughout the world, elsewhere much more than in the United States, people suffer from inadequate nourishment. These inadequacies may involve the total intake, the proteins and amino acids, the vitamins, and the minerals.

Loss of weight is not necessarily an indication of under nutrition nor is maintenance of weight assurance that the intake is proper. Troubles of salt and water balance such as occur in a variety of conditions affecting the heart, kidneys, liver and glandular organs may greatly affect the body weight. Starvation due to loss of appetite or profound neuropsychiatric disturbances produces nutritional disorders. While thehuman body can build up reserves of some substances, others are used up daily and must be regularly replenished. The effects of under nutrition may be aggravated by excessive action of the thyroid, by heat and by cold.

The regulatory mechanism of the body provides for using up fat to provide energy, before drawing on the vital protein. A gram of fat provides nine calories. A gram of protein or carbohydrate yields four calories. The body conserves its protein, and for that reason a fat person can stand starvation much better than a thin one. The carbohydrate is stored in the liver as glycogen, and this is used up in a day or two of starvation.

Carbohydrate and fat conserve protein. The protein consists of amino acids, of which ten are essential. Twelve other amino acids are classified j as nonessential. People on a high carbohydrate diet can develop protein deficiency because they have not had enough protein or because they have not had the essential amino acids in their protein. Eggs, meat, and milk best supply the essential amino acids. Growing children and pregnant women and nursing mothers need excess protein.