Nutrition (2) - Thermal Energy: Carbohydrates and Fat

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Thermal Energy

Its primary sources: carbohydrates and fat

Man derives energy from his food and burns it in the processes of growth, in regulating the body's heat, and in all manner of work. Even in a state of rest there are many internal processes that burn energy, such as the continuous beating of the heart, the movements of breathing, and the processes of digestion in the stomach and the intestines.

The body's activity in performing its functions depends on energy, which is naturally available in food, its proportion varying with the kind of food. The need for it varies with the individual's activity and age. Children and adolescents, for example, need more energy than others do, because they are in the stage of growth and maturing. The average need of the ordinary active adult is 3,000 Calories a day.

The maintenance of the body's heat is essential to preserving the balance between what a person gains of energy and what he loses. If the former exceeds, the result is an increase in the body's weight. It is desirable that the body's weight should increase a little during the stages of growth and maturing, and likewise during illness and emergencies. As for the person who is excessively fat, his internal organs labor under the strain of exhaustion, and he is exposed to various diseases such as diabetes and heart ailments. If, on the other hand, the case is reversed and a person burns more energy than he gains, his weight decreases and he becomes prone to certain diseases such as tuberculosis and the common cold.

The primary sources of energy: carbohydrates and fat

Carbohydrates, or starches and sugar:

Carbohydrates are the most important sources of energy and the most economical. They are made up of the various kinds of sugar and starch; they circulate in the blood in the form of glucose (or grape sugar), and are stored temporarily in the liver in the form of glycogen (or liver sugar), while the surplus is stored in the form of fatty tissue. Carbohydrates are used in carrying out muscular movements, and this function is affected by the working of the pancreas, the pituitary gland, and the adrenal glands. Their most important sources are from the plant world: vegetables abound in starch and cellulose and in small quantities of sugar. Cellulose is the fibrous matter in plants which aids digestion by reason of its bulk. Grains and potatoes are rich in starch, and fruits are among the most important sources of sugar; some of them, such as apples and lemons, contain ample quantities of cellulose. As for honey and the various sweet syrups, they offer sugar in an easily digested form.

Fat:

Fat is another source of energy; it is of high "caloric" value, and it aids digestion, combustion, and the assimilation of protein and of certain minerals and vitamins that dissolve in fat. It is, moreover, an essential element in the formation of all the body's cells. The nutritive value of fat differs from the fuel value of the other energy-producing foods: animal fat is an important source of vitamins A and D, while vegetable fat is an important source of vitamins E and K. The scientists of this branch affirm, as a result of recent experiments, that beans, wheat, olive oil, and egg yolk contain essential fatty acids. Some kinds of fat and fatty acids have a toxic effect in the body; yet their deficiency causes disturbances in the body. It has been found, for example, that food free of fat causes a deficiency of thiamine, and also causes certain kinds of eczema; indeed, a lack of fat may cause loss of hair, and may lead to a disturbance in the function of the kidneys.

The average daily need of a person for fat amounts to 75–150 grams. Its most important sources are animal substances such as butter, cream, cheese, egg yolk, meat, and fat. From plants an easily digested fat is extracted, such as the oils of vegetables, pistachios, walnuts, etc...