The desire for food is appetite while hunger is the sensation caused by fairly frequent and rhythmic contractions of the empty stomach, thus causing a desire for food. Appetite may be a consequence of hunger, but it does not always follow.

Studies on man and animals have given us a scientific basis for the conclusion that there is a selective mechanism which controls eating, which functions through appetite or the desire for food. Careful observations show that appetite encompasses psychic factors and may be brought about not only by hunger.

There can be appetite without hunger. An attractive, tasty meal may arouse the desire to eat even after all hunger has been appeased. We continue to eat because of the acquired liking for certain foods and of the memory of pleasant experiences with food. Some factors that may influence appetite are:

The desire for food or appetite and sensations of hunger are signals which maintain the bodily supply of nutrients and operate for the welfare of the individual and the race. Experts in nutrition speak of the appetite and hunger as regulating mechanism, as the stop and go feature indispensable for race survival. The hunger pain develops to give us a reliable impulse for beginning our meals and the inner feeling of satisfaction of satiety, tells us when to stop.

Abnormal Appetite: If a dietary is adequate in quality and quantity of all nutriments, the healthy child will not have an abnormal craving for sweets, especially sugar, a food of high calorie value, but low in nutritive value. A large amount of sugar stimulates the flow of fluid in the stomach and the resulting volume of liquid may stop hunger contraction with the consequent loss of appetite.

Food likes and dislikes enter into the feeing of every family. Appetite is not an infallible guide to good nutrition, as it is subject to prejudice and imitation and may be altered by conditioning or learning. Appetites vary secondarily with age, customs, temperature, and economic status.

Food and Allergy: Allergy is a condition of hypersensitivity to certain substances which in the great majority of human beings produces no ill effect. This may be caused in one individual by a certain substance and by an entirely different one in another. The most common allergy-producing foods are milk, eggs, and cereals; next in order are fish, nuts, and pies.

There are no typical symptoms in allergies as in a communicable disease, partly because very different tissues of the body respond. Among the many symptoms are redness and swelling of the eyes, running of the nose, headache, asthma, such skin conditions as urticaria and eczema and gastrointestinal disturbances as diarrhea and colic. Apparently, there is an inherited tendency to allergy which is not specific.