American Fitness Professionals & Associates

By: Ruth Dalsky, MEd

Adolescence is a particularly difficult time for young girls, especially from a nutritional perspective. By definition, adolescence is “the period of physical and psychological development from the onset of puberty to maturity.” That leads to the possibility of quite a few years of potential nutritional problems and turmoil, for both the girl and her parents. Puberty involves the maturation of the entire physical body, the achievement of reproductive maturity, and all the psychological changes that adolescents experience. Unfortunately, the nutritional demands during this time are usually overlooked.

Both boys and girls pass through several stages of growth during puberty. The first relates to sexual maturation. In this stage, increasing amounts of the reproductive hormones need to be synthesized, then released into the body. During this time, most youth experience a growth spurt, in which muscle mass and bone length are both increasing. Nutrients, such as proteins and the various minerals necessary for lean mass and bone synthesis, are needed on a timely basis - meaning right then and there! Of course, additional calories to supply the energy for growth and development are also critical during this time.

Girls will experience menarche, the initiation of the menstrual cycle, in the first phases of adolescence, and will need extra vitamins and minerals to support this process as well. The nutrient most obviously needed for menarche is iron, for replacement of blood cells lost during menstruation. Consuming a diet that contains adequate amounts of iron is oftentimes problematic for young girls.

Iron is found in a variety of sources, but only in small quantities. The quality and source of the iron in the diet is an important consideration to prevent a deficiency. Iron derived from plant sources (non-heme iron) is poorly absorbed in comparison to iron derived from animal products (heme iron). Thus, girls who don’t like meat or who are experimenting with vegetarianism are at increased risk of iron deficiency - or frank anemia.

Calcium is also an essential nutrient to support growth and development during adolescence. Teenagers (as well as adult females) are encouraged to increase their intake to about 1200-1500 mg of calcium per day. The best food sources are orange juice 8 ounces= 300 mgs. Sweet potato’s= one small contain 70-80 mgs of calcium. Supplements are a valuable adjunct to the diet in many cases, for the average daily intake of calcium is only 400 mg, a third of the required amount. That’s not enough to support healthy bone development, or the achievement of peak bone mass.

Plant Sources of Calcium

The most evident, and generally the most difficult, stage of development in adolescence is the growth spurt. Girls, in particular, are extremely sensitive to these weight and structure changes. It’s during this time that gender-dependent fat begins to accumulate, changing the contour and the weight of the girl. If the girl is eating the typical teen diet high in fat and sugar, she’s likely to experience an excessive fat gain. She’s not happy, and this excess fat might make future weight management more difficult.

Adolescence requires a fine nutritional balance between enough calories and nutrients to insure adequate growth needs, but not so many calories that lead to excessive fat gain. It’s also a time to emphasize the concept of body composition and to de-emphasize the girl’s weight on the scale. Doing so may prevent an eating disorder.

Pre-pubertal males and females usually have similar body composition, with a body fat at about 15-19%. During puberty, however, females will generally gain more body fat to a normal healthy level of about 23%. This is an exceptionally vulnerable time for young females, who may fear these body changes or are experiencing other emotional pressures. They are likely to engage in disordered eating practices if they gain weight too quickly, or have distorted body images. Girls may go on diets at this time, or eliminate food groups (especially meat) as a means of preventing weight gain. But they must have calories to support their growth and development!

To illustrate the specific energy needs of children and teenagers, the following table may be useful: Energy needs:

Children 7 to 10 yrs.    2400 calories range = 1650 to 3300
Females 11 to 18 yrs. 2200 calories range = 1200 to 3000
Males 11 to 18 yrs.      2800 calories range = 2000 to 3900  

Protein is another important consideration for teenagers. It is an essential nutrient responsible for adequate growth and repair of all body tissues. During growth cycles, the demand for protein is at its peak. Adolescents need at least 45-60 grams of high quality protein per day.

Other important nutritional suggestions for the adolescent girl include eating a balanced diet, avoiding irregular meals (e.g., skipping breakfast or bingeing late in the evening) and not wasting all her calories on fat-free foods that may not be nutrient dense. Teenagers, just like adults, can fall prey to advertising, peer pressure, sodas and fast foods. These practices do not support optimal growth or a healthy body composition. But try to tell a teenager that!