American Medical Association Family Medical Guide - American Medical Association [224]
Late puberty
Pubic hair fills in during late puberty. The penis grows longer and thicker, and the skin of the scrotum and penis darkens. Facial hair starts to grow, mostly on the upper lip and chin. At this stage, a growth spurt takes place, and boys get noticeably taller.
Maturity
At this stage, boys reach physical and sexual maturity (usually between ages 18 and 21). The dramatic growth in height slows considerably. Pubic hair may have spread to cover the inner thighs. Hair may start to grow on the chest.
Prepuberty
Early puberty
Middle puberty
Late puberty
Maturity
Nutrition
Not eating the right foods, eating too much, or not eating enough during adolescence can lead to lifelong health problems or life-threatening diseases such as obesity, cancer, diabetes, heart disease, and osteoporosis. The tremendous physical growth that occurs during puberty requires good nutrition. To meet their energy needs throughout the day, teens should eat at least three healthy meals, including a good breakfast. Teens often eat on the run. A wide variety of healthful foods available at home—such as fresh fruits, low-fat cheeses and yogurt, and cut-up raw vegetables with a low-fat bean dip or salsa—may help keep teens from eating the high-fat, high-sugar, high-calorie foods they normally reach for first. Sodas and diet sodas have little or no nutritional value.
Calcium
Teens, especially girls, need to eat foods that are high in calcium, such as low-fat dairy products, fish with edible bones (such as salmon and sardines), and dark green vegetables (such as collard greens, broccoli, and kale). They should have three or more servings a day of calcium-rich foods. Nearly all of a person’s total bone mass is formed by the end of the teen years. Children who don’t take in enough calcium may not develop their maximum potential bone mass. Building optimal bone mass by doing weight-bearing exercise and eating foods high in calcium can help prevent or delay the onset of the bone-thinning disorder osteoporosis (see page 989) later in life.
Iron
The daily requirement for iron increases dramatically starting at age 10, especially between ages 11 and 18, because of increased muscle mass and an expanded volume of blood. Iron can be found in animal foods such as beef, chicken and turkey (especially the dark meat), or fish. Strict vegetarians (see page 43) can get their daily supply of iron from plant foods such as dried beans, leafy greens, nuts, and dried fruits, but they will have to eat a larger volume of them to get sufficient iron. Adolescent boys need more iron than when they were younger because of their increased growth rate. Girls need even more than boys to replace the iron lost during menstruation. Girls who lose a lot of blood during heavy menstrual periods are at risk of developing iron deficiency anemia (see page 610). Symptoms of iron deficiency anemia include fatigue, irritability, headaches, and tingling in the hands and feet.
Folic Acid
Folic acid, a B vitamin, is an essential nutrient, especially for girls and women of childbearing age. A deficiency of folic acid during pregnancy can cause neural tube defects such as spina bifida (see page 398) in a fetus. All adolescent girls should get at least 400 micrograms of folic acid every day, either in a supplement (all multivitamin supplements include folic acid) or in food. Good sources of folic acid include green, leafy vegetables; fruit; cheese; legumes; liver; and fortified breakfast cereals and other grain products.
Calorie Intake
Calorie needs depend on a teen’s individual growth rate and physical activity level. During the rapid growth spurt between ages 15 and 19, some boys are able to eat up to 4,000 calories a day without gaining weight. However, once this growth spurt ends, they can quickly gain unwanted pounds that will be difficult to lose as they get older. Girls usually stop growing by age 15 and tend to be less physically active than boys. Girls (and inactive boys) can easily become overweight if they consume more calories