Youth is a period of significant physical development. Body-growth is being completed; the organs of the maturer functions of the body are developing; the body is maturing physically. The individual's mental powers are seeking more definite expression. The social relations of life are becoming more conscious. Life at this age is therefore full of newness and moves rapidly in its changes.

The growth-impulse of the body needs plentiful nourishment for free and full growth. Whether physical growth that is delayed by lack of nourishment can be effected after indefinite postponement is not yet known.

Ductless glands of the body play a more important part in its development and health than was realized earlier. The thymus gland delays too early development of the later body-functions. The thyroid gland promotes the differentiation of developing organs. Intricate interrelations are found to exist between all such glands. Their wholesome functioning is of greatest importance to growth and mature health. Healthful youth furthers this. Disturbing illness prevents normal development and functioning of these glands.

Food that is strengthening and sustaining rather than stimulating is the need of youth. Such specific growth foods as egg-yolk and butter-fat should be abundant in youth-diet. Mineral salts too are particularly needed. Excess of food and starvation alike remove these from the body. The body at this time is not very resistant to disease. In fevers the nitrogen-waste is extreme. Science now finds this lessened by feeding carbohydrates in abundance. This must, however, be under a physician's direction. Both scientists and physicians are now interested in diet as never before.

See Sensible Diet, p. 213; Diet-Quantities, p. 219.