Diet compensates for the energy lost during various activities performed by the body in / during the day. A correct or balanced diet is one which provide maintenance of the body as well as energy requirements and, when necessary for growth and reproduction. Essential elements lost from the body by excretion must be replaced. Some other important factors, about diet, which need consideration, are:

1) Its energy value

2) Quality and quantity of primary foods, mineral & vitamins

3) Digestibility

4) Cooking

5) Psychological factors

6) Cost

Energy Value:

The caloric value of dietary intake must equal the energy expended as heat and work if body weight is to be maintained. When the caloric intake is insufficient, body stores of protein and fat arte catabolised, and when the intake is excessive, obesity results. Three thousand calories have been estimated as the daily requirement of the average man.

Quality and Quantity of the Food Constituents:

• Primary foods: It is advisable that 10-15 percent of the total calories should be obtained from proteins, 20-30 percent from fats and 50-60 percent from carbohydrates.
• Minerals: Small amounts of inorganic salts are always lost during days work and must be replaced. Deficiency of Ca, P, Fe, & I is common in human’s diets deficiency of other elements is rare. There is no uniformity of opinion as to the amounts of minerals which should be taken.
• Vitamins: Though do not provide energy, are essential fro metabolism of energy providing nutrients, regulation of various body processes and for maintenance of life.

Because there are minor differences in metabolism between mammalian species, some substances are vitamins in one species and not in other.

Digestibility of the food:

A factor of considerable importance in dietetics is the ‘digestibility’ of the food. The primary foods must be of such a nature that they can be both digested and absorbed easily. Absorption is usually better with mixed diet than when one substance is taken alone.

Cooking:

Process of cooking & preparation bring about a number of changes in the physical and chemical properties of food. Inedible portions are removed and harmful organisms are destroyed. Cooking also increases both the water content and digestibility of food. Overcooking may affect adversely the quality of food. Proteins get coagulated and their digestibility decreases. Fats are little changed in cooking.
Cooking involves loss in nearly all foods, especially of soluble substances in boiling process. Vitamin B1 and C are especially liable to destruction when vegetables are cooked. The practice of making soups from the liquids in which meat and vegetables are boiled conserves soluble constituents such as salts and sugars which would otherwise be wasted.

Psychological Factors:

The consumption of food very much depends upon the mood or psychological state of an individual. Worry, anxiety and depression may diminish the ape tile or even upset digestion through imperfect mastication and secretion of digestive juices. On the other hand when a person is cheerful or in a gay mood, the food may appear more attractive and tasty.

Cost:

Family income has a big influence on the quality of food. Most of the times it is true that people coming from lower income group are less resistant to infectious diseases such as whooping-cough, measles, diphtheria and tuberculosis: this resistance can be improved by better nutrition. Chances of rickets and nutritional anemia are also higher in the individuals coming from lower income groups, since these diseases are attributed to a lack of minerals and vitamins which are not present abundantly in low quality food.