I. Physiological functions
Firstly, our body performs several activities- Voluntary and involuntary. There is not a single moment in life when the body is completely at rest and does not require energy. Even when the body is taking rest (i.e. during sleep) energy is required to out the involuntary processes of the body like digestion, respiration, circulation, beating of the heart etc. Energy is also required to carry out professional, household and recreational activities. This energy is supplied from foods like carbohydrates and fats.
Secondly, food provides materials for tissue building, growth and body repair, is mainly supplied through foods like proteins and minerals. The muscles, bones different parts of the body are built up and maintained by the proteins supplied by the food. Minerals like calcium, iron and phosphorus affect the formation of blood and skeleton tissue (bones).
Thirdly, food protects the body against diseases. Here, vitamins play a vital in regulating body processes like growth, eyesight, health of the skin, formation of pr teeth and good digestion. Minerals also act as catalysts for many biological reactions within the body. They are required for building of bones, muscular contraction, and transmission of messages through the nervous system and the digestion and utilization of nutrients in food. Vitamins and minerals are needed for maintaining the general health of the body.
Fourthly, water and roughage in foods act as regulatory foods that are needed for the normal functioning of the body. In importance and need, water is next to oxygen. It is required in large amount to regulate body processes such as digestion, excretion, maintenance of body temperature and the electrolyte balance. Roughage helps in good bowel movements.
II. Psychological Functions
Foods satisfy certain emotional needs of human beings and act as a source of security. An infant learns security from the way his mother feeds him. Similarly, a growing child gains confidence and a feeling of belonging, when he knows there is food in the house and he will be fed. People feel reasonably secure, when they have enough food stored up to take care of them during scarcity.
Food is also an outlet for emotion. As a relief from tension, one may not eat or over eat. For some people, loneliness and boredom are relieved by continuous nibbling at food.
Food is also used as a weapon, when an insecure child refuses to eat, thereby drawing the attention of the parents especially the mother.
III. Socio-cultural Function
From ancient times the socio-cultural life of human beings has been revolved around food. Food is used as a symbol of hospitality and friendship throughout the world. We express our hospitality to a guest through an offer of food or drink. In social gatherings, food serves as an instrument for developing social relationships. Here the menu plays an important role, and the nutritive value of it is not given much emphasis.
Every family has its own peculiar meal pattern. This is governed by the social class to which he belongs, the economic condition, religious belief and social attitude. Today, food has brought about an integration of different cultures, race, ideals and thinking of people, by accepting and relishing others dishes. For example, we Indians are now relishing Chinese, European and other Intercontinental dishes.
Thus, for an average man, food is much more, than a substance supplying nutrients for health. It is the sum of his culture and traditions, emotional outlet, gratification of pleasure and a relief from stress, a means of communication, security, status- all of these interwoven in the fabric of life and unconsciously expressed in food likes and dislikes.