The teenage years are trying times in a lot of ways, especially in terms of nutrition. Adolescence is indeed a period of high nutritional risk, when the increased demands for nutrients are often met with poor choices of foods, unhealthy eating habits, and deficient intakes of calories and protein as well as many vitamins and minerals.

Adolescence usually begins at age 10?12 in girls and 12?14 in boys. There are not only new demands, but also many physiological changes because of the sexual hormones being released. Body composition also shifts, with girls increasing their percentage of fat and adding curves, while boys tend to increase protein and muscle development. During these years, young men may gain 15?20 pounds in weight and 4?5 inches in height per year, while girls may add 13?18 pounds and grow 3?4 inches yearly. The main years of growth are between ages 11?16 years for girls, 13?18 years for boys.

The nutritional problems of adolescence are probably related to the rebellious nature of these years. Teenagers eat what they want and when; they are hard to feed and harder to influence regarding dietary changes. Peer pressure is great. They often have limited food intake and poor nutrition, with a diet high in sweets and refined foods, fried foods, fast foods, and junk foods. The adolescent diet is often very high on the glycemic index, meaning more rapidly absorbing sugars. A diet higher in the complex carbohydrates such as whole grains and legumes will help to balance this. Luckily, though, for many teenagers the great demands for nutrients to support growth will increase their appetite for more concentrated protein foods and nutrient-rich foods. Some active adolescent males in particular may easily consume 4,000 calories daily.

Boys generally tend to eat enough food, but they may be deficient in nutrients because they often avoid vegetables, whole grains, and other whole foods. Teenagers who eat more refined foods without taking supplements commonly develop deficiencies. Teenage girls tend to eat less, as they are concerned about their weight, and the changes in fatty tissue increase this concern. Thus, they also may consume a diet deficient in nutrients. With the beginning of the menstrual cycle, there are greater demands for iron and other nutrients as well. Problems of bulimia and anorexia nervosa are more common in teenage girls, and will be discussed further in the Weight Gain program in Chapter 17. Teenage pregnancy can be a huge problem because of poor nutrition and deficiencies existing before pregnancy begins, let alone the challenge to a developing emotional system. Poor nutrition during pregnancy or prior to it greatly increases the risk of complications.

Obesity in adolescence usually results from poor food choices and laziness or lack of exercise. Other habits can also lead to weight gain. For example, more average daily time spent watching TV is associated with higher weights, also resulting from less activity and more snacks. With increased calorie intake during these growth years, there is an increase in the number and size of fat cells. This can lead to lifelong weight problems. Diet changes, sensible eating, and exercise are the best ways to counteract excessive weight gain, even in youngsters. Like eating habits, exercise habits are often created early in life, and once set, are harder to change. This is also true for attitudes toward health and life. These factors?eating and exercise patterns, and attitudes?are all important in generating long-term health.