After creation of the universe , the God of Destruction “Lord Shiva” ordered His godly carrier a bull “Nandi” to go to Earth and convey the inhabitants that they will take food one time in seven days.Nandi went uttering and remembering the order loudly in the fear of forgetting it.But the worst happened , he reached the earth only to announce that Lord Shiva has ordered the inhabitants to take food seven times a day.And that was totally reverse.Then he returned to heaven to convey Lord that His orders has been communicated.Knowing the totally reverse communication God became angry and said that as the bull has done the mistake he will do the cultivation of land for human to produce the huge quantity of food that will be required .And since then the bull is doing the hard work for mankind.
Whatever may be the folk tale the fact is that human has got a good appetite for food.It may be lost in various occasions starting from a trivial fever to more dreaded cancer.
Loss of appetite is different from anorexia many times used as synonym.Loss of appetite means there is no feeling of hunger and anorexia means there is hunger but no desire to take food.One feels hungry by the site , smell or at the usual time of taking food.So it is essentially centrally controlled .There is a center for appetite and satiety in the brain which regulate intake of food.
Apart from minor and temporary causes of loss of appetite ,there are more important causes for loss of appetite and anorexia.One condition called Anorexia Nervosa seen in young and adolescent ladies where there is anorexia probably due to hormonal imbalance.Here the patient does not take food and becomes bony thin.This gets cured by hormonal support and assurance .
Next important cause is old age ,here the taste buds of tongue gets destroyed , there is no taste of food and consequently the person does not want to take food.Vitamin supplementation relieves it to some extent.
Gall bladder disease,liver disease and disease of pancreas can cause loss of appetite.
Loss of appetite with new found anaemia in old people points to cancer of stomach.Any cancer can be a cause loss of appetite.
There area host of other causes.
Diagnosis and treatment depends on the cause.