ABSTRACT
Adolescence begins with puberty and sexual maturation. Usually, for girls adolescence begins at about thirteen years and for boys at about fourteen years; but sexual maturation is gradual, and the time varies from individual to individual. In adolescence it is obvious that height and weight increase markedly. In boys, the acceleration in growth, often called the "growth spurt", takes place between the twelfth and fourteenth years; in girls, this acceleration occurs between the tenth and twelfth years. In addition to changes in height and weight, body proportions also change, although not all parts of the body increase in size at the same rate. Sometimes adolescents seem to be lethargic and prone to avoid physical activity, but if an activity involves doing things that they enjoy, they usually display boundless energy and strength. Investigators in the field of nutrition have long maintained that the quality and quantity of food are important factors in the health of children.
