Meeting nutritional needs during adolescence

Dr. Elisabeth Rousseau, Hôpital Ste-Justine

Children and youth represent about 25% of the total population in Canada. Even though Canada is described by the United Nations as being one of the most developed societies of the 20th century, the last decade has been marked by striking family disorganization and economic crisis. It has been estimated that about one fifth of Canadian children and adolescents live below the "poverty line"1 and are consequently at greater risk for school failure and dropout2,3,4 and more prone to health related problems, as well as dietary inadequacies5,6. However there is an increased interest in health and nutrition. This has led to an increase in media coverage, but unfortunately not all information is accurate and the result is confusion.

Adolescence is a period of rapid physical growth, requiring adequate nutrient intake to meet growth requirements. It is also a period of emotional and psychological change, sometimes of rebellion during which there is tendency among other things to reject conventional dietary habits. As a result adolescents do not always meet their nutrient needs7 and may have specific nutritional problems. Many adolescents already possess risk factors for chronic diseases. Increasing attention has focused on this age group for reducing high risk behaviors, preventing future health problems, many of them having their roots in early age. With these concerns in mind, the Canadian Paediatric Society's Nutrition Committee has reviewed the previous statement published in 19838 and what is presently known about normal requirements9,10 obesity, the nutrient requirements of adolescents involved in sport, the needs of pregnant teenagers, and, finally, fast food, food fads and nutrition education.

References

1.Normal nutritional requirements

Physical growth and nutrition are intimately related. Optimal nutrition is imperative for achieving full growth potential1. Failure to consume an adequate diet (quantitatively and/or qualitatively) can result in delayed sexual maturation and can slow or arrest linear growth. At this time body composition diverges between males and females, explaining the difference in requirements and performance2. The greater amounts of skeletal and lean body mass combined with a longer duration of growth explain the male's greater nutrient needs. On the contrary, girls deposit more subcutaneous fat, so that by the end of adolescence females have about twice the percentage of body fat, but only two thirds of lean tissue as that of their male counterparts. During puberty, total nutrient needs are higher than at any other time of life. Recommended Nutrient Intakes for 10 - to 24-year-old Canadians are provided in Tables I and II.

Energy needs for individual adolescents vary according to sex, age, body size, pubertal development, and physical activity. It is important to appreciate that the recommended nutrient intakes for energy are set as means for the particular groups. Since individuals may vary by approximately 30% above or below the mean, caution must be employed in using the recommendations to determine an individual's energy needs.

Studies of actual energy intakes have shown wide ranges for any given age, but are more related to physiological development than to chronological age. During adolescence3, girls appear to consume their peak caloric intake, about 2550 kcal (10710 kJ) at the time of menarche (around 12 years). This peak demand is followed by a slow decline. In boys (beginning approximately 2 years later than in girls) the caloric intake appears to parallel the adolescent growth spurt, increasing until age 16 years to approximately 3400 kcal (14280 kJ) and then decreasing by 500 kcal (2100 kJ) by age 19 years.

Proteins, lipids, carbohydrates.

Patterns of protein 4 intake mirror those of energy, especially for males being generally higher between 16-19 years old. Protein constitutes 12% to 14% of the total energy intake in typical North American adolescents. The recommended intakes, however, are lower and constitute 6% to 8% of total energy needs (Tables I and II). Thus, Canadian adolescents who eat a mixed balanced diet will meet or exceed their protein requirements, provided they ingest enough to meet their energy needs. Inadequate total energy intake despite adequate protein intake may arise during efforts at weight reduction; it results in decreased nitrogen retention and may therefore cause sub optimal growth. Attempts at weight reduction by dietary restriction are therefore contraindicated during the rapid growth spurt of adolescence.

Patterns of fat 4-5 intake reveal that the typical adolescent diet contains excess dietary fat, with approximately 37% calories obtained from fat, 13% of which is saturated fat. Changes in serum lipid levels in the adolescent male are considered to be a significant risk factor for adult hyperlipidemia. Serum high density lipoprotein (HDL) levels decrease in boys yet remain constant for girls6. Some adolescents severely limit their fat intake leading to inadequate energy consumption. Females are more likely to meet cholesterol recommendations than males. Thus the Canadian recommendations state7 that the fat content of the diet should be reduced to 30% of total energy and the intake of saturated fat should not exceed 10%.

Dietary guidelines also recommend that more than 55% of calories should be derived from carbohydrates (CHO) with emphasis on foods rich in complex carbohydrate and fiber derived from grains, fruits and vegetables. The typical adolescent dietary patterns4-5 reveals few of these foods8, but is relatively high in simple sugars (soft drinks, candies, flavorings added to milk...). Increased intake of CHO, reduced fat consumption and moderation of portion size will help adolescents achieve dietary guidelines.

Vitamins 5

The requirement for most vitamins rise markedly during the growth spurt of adolescents. The rapid rate of skeletal growth demands more vitamin D, A, C and E required for the new cells. The increased tissue synthesis demands more vitamin B12 and folate required for DNA and RNA metabolism. Strict vegetarians (vegans) are at risk for B12 deficiency.
Many teenage girls take oral contraceptives. These may increase their need for several nutrients (e.g., vitamin B6 and folate)8 their absorption being impaired by the oral contraceptive. Normally, these nutrients are present in sufficient quantities in a balanced diet that includes milk products, meat, poultry, fish, vegetables and fruits. Adolescent girls who are taking oral contraceptives should be counseled to pay attention to their diet, to avoid skipping meals and to take a balanced variety of food.
To meet the increased energy needs of adolescence more thiamin, riboflavin and niacin are required to promote the release of energy from CHO, fat and prtein.

Minerals5

Because of the adolescent growth spurt the need for three minerals (calcium, iron, zinc) is of particular importance.

Calcium: Calcium requirements increase with the rapid growth of adolescence and the increase in the size of the skeleton. During peak growth the amount of calcium deposited in the skeleton rises to 200 mg/d in girls and 300 mg/d boys. The efficiency of calcium absorption increases with requirement and bears an inverse relation to intake: the lower the intake, the more efficient the absorption.. Dietary requirements during adolescent growth will thus be influenced by the efficiency of absorption and the pre-existent state of the skeleton. In the event of long-term sub optimal calcium nutrition, calcium deficiency may arise during pubertal growth. The current Recommended Nutrient Intakes (RNI) should be between 700 to 1,100 mg for adolescents9. However some authors have proposed a higher level of daily calcium intake (1500 mg) in order to prevent any risk of osteoporosis later in life10-11. Calcium intake tends to be low in adolescents diets especially in girls12-13. Advertising campaigns encouraging milk consumption have had positive repercussions mainly among boys. Foods rich in calcium include milk products, bones of canned sardines and salmon and certain deep green vegetables. Canada's Food Guide to Healthy Eating14 recommends 3-4 servings of milk products per day for preadolescents and adolescents 10-16 years of age per day.

Iron: There is an increased need for iron in both males and females during adolescence; in males because of the increase in muscular mass and the expansion of blood volume, especially during the peak growth, and in females due to growth, menstrual losses and sometimes decreased food intake. Iron absorption is influenced by many factors, including age, iron status, state of health and the chemical form of iron ingested. The bioavailability of heme-iron found in meat, fish and poultry is particularly high (ranging from 23% to 35%), depending upon irons stores. Less non-heme-iron is absorbed (2% to 20%) depending upon the iron status of the individual. It can be increased by vitamin C and decreased by tannic acid (present in tea), phytates (present in vegetables), calcium and phosphate salts, and antacids.

About two decades ago the Nutrition Canada Survey15 showed that, although the prevalence of anemia in teenagers was very low, 25% of girls had low iron stores. This is particularly true for lower socioeconomic groups and pregnant teenagers. The mean daily iron intake of females aged 12 to 19 years was 11 mg. Recommended Nutrient Intake (RNI) for teenage girls is 13 mg of iron per day. The Canadian mixed diet contains 5 to 6 mg of iron per 1000 kcal (1.2 to 1.4 mg/1000 kJ). Thus, the average daily energy intake of adolescent females (only 2243 kcal) is marginal in iron16. Adolescent girls should therefore eat foods rich in iron, including red meats, green vegetables and iron-enriched cereals. A good dietary habit for adolescents would be to eat a breakfast that included a fortified cereal (providing 4 mg of iron per serving) and a serving of fruit or juice rich in vitamin C. Pregnant adolescents require iron supplementation to meet their iron requirements.

Zinc17: Adolescents undergoing rapid growth or pregnant teenagers are at risk of zinc deficiency. Good sources of zinc include meat, eggs, milk, seafood, leafy and root vegetables, all foods fund in a balanced mixed diet.

Table 1 - Recommended Nutrient Intakes
Age Sex Weight kg Energy kcal Protein n=3 PUFAa g n=6 PUFA g Ca mg Ph mg Iron mg IZinc mg
10-12 M
F
34
36
2500
2200
34
36
1.4
1.2
8
7
900
1100
700
800
8
8
9
9
13-15 M
F
50
48
2800
2200
49
46
1.5
1.2
9
7
1100
1000
900
850
10
13
12
9
16-18 M
F
62
53
3200
2100
58
47
1.8
1.2
11
7
900
700
1000
850
9
13
12
9
19-24 M
F
71
58
3000
2100
61
50
1.6
1.2
10
7
800
700
1000
850
9
13
12
9
Pregnancy (additional)
1st Trimester 100 5 0.05 0.3 500 200 0 6
2nd Trimester 300 20 0.16 0.9 500 200 5 6
3rd Trimester 300 24 0.16 0.9 500 200 10 6
Lactation (additional) 450 20 0.25 1.5 500 200 0 6
a. PUFA, polyunsaturated fatty acids
Reprinted form Health and Welfare Canada. Nutrition Recommendations. The Report of the Scientific Review Committee. Ottawa 1990.


Table 2 - Recommended Nutrient Intakes
Age Sex Thiamin mg Riboflavin mg Niacin NEc Vit A REa Vit D mg Vit E mg Vit C mg Folate mg Vit B12
10-12 M
F
1.0
0.9
1.3
1.1
18
16
800
800
2.5
2.5
8
7
25b1
25b
120
130
1.0
1.0
13-15 M
F
1.1
0.9
1.4
1.1
20
16
900
800
2.5
2.5
9
7
30b
30b
175
170
1.0
1.0
16-18 M
F
1.3
0.8
1.6
1.1
23
15
1000
800
2.5
2.5
10
7
40b
30b
220
190
1.0
1.0
19-24 M
F
1.2
0.8
1.5
1.1
22
15
1000
800
2.5
2.5
10
7
40b
30b
220
180
1.0
1.0
Pregnancy (additional)
1st Trimester 0.1 0.1 1 0 2.5 2 0 400* 0.2
2nd Trimester 0.1 0.3 2 0 2.5 2 10 400* 0.2
3rd Trimester 0.1 0.3 2 0 2.5 2 0 200 0.2
Lactation (additional) 0.2 0.4 3 400 2.5 3 25 100 0.2
a. Retinol Equivalents
b. Smokers should increase vit C by 50%
c. Niacin Equivalents
Reprinted form Health and Welfare Canada. Nutrition Recommendations. The Report of the Scientific Review Committee. Ottawa 1990.
* Canadian Task force on Periodic Health Examination. 1994 update: 3. Primary and secondary prevention of neural tube deffects. CMAJ, 151 (2): 159-167, 1994

Conclusion

The nutrient requirements during adolescence are directly related to the phase of growth and sexual maturation. In addition to these factors, individual requirements will vary greatly according to the level of activity and body configuration. Standardized dietary recommendations, such as those given according to age, should therefore be cautiously interpreted when one is dealing with individual children.

Canada's Guidelines for Healthy Eating14 provide recommendations to adolescents for promoting health and diminishing risk of chronic diseases, such as heart disease, stroke, diabetes mellitus, osteoporosis and some types of cancer:

References

2.Obesity

Obesity is a chronic disease and represents one of the most common nutritional disorders affecting North American adolescents1-2-3-4. It may interfere with the development of a satisfying self-image (low self-esteem sometimes precedes the onset of obesity) and social status, and with normal psychological development. Some obese adolescents have difficulties being accepted by their peers, their superiors and even their parents. This rejection may well lead to a negative body image, low self-esteem and even serious psychological illness5-6-7. Often these psychological problems lie not only with the adolescents but also within the family8.

From a pathophysiologic view point, heredity most often plays a predominant etiologic role9-10-11-12-13. This genetic predisposition may be reinforced through certain characteristics of the environment in which adolescents are raised. Among the risk factors linked to the environment14-15-16-17, are:

Apart from the psychological consequences obesity in adolescence predisposes the individual to more serious physical disabilities in adult life18-19-20-21-22-23. Very obese adults are at a higher risk of death and have a greater predisposition to diabetes, hyperlipidemia, cerebrovascular and renal disease, hypertension, cholecystitis and orthopedic disease than do non obese individuals. In addition, obese individuals have greater obstetric and surgical risks, and their postoperative course may be complicated by pulmonary and vascular disease.

Prevalence

Because no standard definition exists at present24, it is estimated that from 5% to 20% of adolescents are obese. The prevalence of children obesity is increasing in some countries like US and Canada25-26. The prevalence varies inversely with social class, between sexes and with age. However, accurate figures are hard to obtain, partly because of the lack of a suitable, universally employed standard for measuring obesity. A number of measures are used to assess the frequency of obesity, but for the most part they are based on weight, height or a combination of these measures, with or without correction for sex and age. Early identification of inappropriate increase in weight for height is important for the clinician.

A more reliable technique, but one less commonly used in clinical practice, is to estimate the proportion of body fat by measurement of skin fold thickness27. Because body composition changes rapidly during childhood and adolescence, it is particularly important to use measures that reflect the proportion of body fat.

Many diagnostic criteria have been suggested28. The simplest consists of saying that a person is obese when his weight reaches or passes 120% of his ideal weight, or when weight exceeds the 97th percentile on a growth chart. However, some adolescents have a bulkier skeleton and can be wrongly considered obese; for them, it is best to measure skin folds with a skin fold caliper.

A triceps skin fold greater than 18 mm in a male adolescent or 25 mm in a female adolescent is consistent with obesity. In practice, the clinician may simply examine the height-weight relationship by performing successively the following steps.

The healthy weight range defined for adults by Health Canada based upon the Body mass index (BMI- or Quetelet index) using the ratio of body weight (kg) to the square of the height (m) does not accurately reflect obesity in adolescence30.

Etiologic factors

More than 95% of obesity is "exogenous" (or primary form) in which no intrinsic cause can be found. They appear because there is imbalance between food consumption and energy expenditure31-32-33. In light of double-labeled water method and energy expenditure studies, it is apparent that the obese individual eats more than is needed34-35.

On average obese male adolescents ingest 16% more energy than required and females 38% more energy. A 2% difference in energy intake over a period of 10 years can result in an accumulation of an extra 20 kg of body fat36. It follows that obesity is associated with a problem of the regulation of energy intake where the obese patient overeats and has difficulty reducing his eating to an energy level which is appropriate for energy expenditure. Exogenous to obesity increases the rate of statural growth, bone maturation and puberty development.

Less than 5% of obesity is "endogenous"37-38 (or secondary form), it results from a genetic syndrome or from an endocrine or neurologic disease. Obesity is part of syndromes such as Prader-Willi, Bardet-Biedl (Laurence-Moon-Biedl), Cohen syndrome and others. Endocrine diseases accompanied by obesity are mainly Cushing's syndrome hypothyroidism and some hypothalamic dysfunctions. For teenage girls, the combination of obesity, hirsutism and amenorrhea is characteristic of the Stein-Leventhal syndrome (polycystic ovaries).

In all cases of exogenous obesity, the "final common pathway" leading to obesity is an energy intake greater than energy expenditure for an extended period. Two important mechanisms that can alter energy intake and expenditure are heredity and lifestyle.

From studies of adopted children9-10-11-12 it is apparent that obesity is hereditary, in that adopted children correlate better with their biologic rather than their adoptive parents, but the degree of heritability is variable. There are also environmental and familial influences that may lead to obesity. Two potential genetically mediated mechanisms that may lead to obesity are an excessive growth of adipose cells at vulnerable times of body growth39 and an altered mode of use of energy sources by the body36.

Environment also influences energy intake and expenditure, largely via factors such as cultural habits, family structure, the parents' knowledge about food and their attitudes toward food and their child, and the psychological and socioeconomic environment.

Current evidence suggests that most fat infants become normal-weight children, but that many fat children and adolescents were fat infants39. There are much stronger relations between obesity in the late preschool years and in adolescence and also between obesity in adolescence and in adulthood.

Obese adolescents often exhibit the following behavior: eating fast, skipping breakfast and lunch, eating heavily at night, eating when not hungry but when food is available, eating when depressed or anxious, eating during other activities such as television watching.

Inactivity is a common finding in many studies of obese subjects40-41. Television is a prominent feature of North American life7. Canadian children watch 14 to 22 hours of television weekly42-43. To what degree does this play a role in the genesis of obesity44-45-46? Different explanations are proposed: the sedentary nature of the activity itself and the consumption of high energy, low nutrient foods while viewing TV, or conversely inactive children are more prone to watch TV.

Treatment

The therapy for obesity is singularly frustrating and is extremely difficult at any age. This is partly because it is often not only the teenager, but the whole family that needs to be treated and because the problem is not just "overweight" but a host of psychological and social problems . The most successful results will be found in the adolescent who wants to lose weight and whose family is willing to change its lifestyle and attitudes in order to help him or her (and often themselves too)8-47. However, it is the adolescent who must face the fact that this disorder requires his or her active cooperation for a successful outcome. Despite all the forms of support from family and others it is the individual who must actually lose the weight. Clinical experience shows that some adolescents and their families are unable to cooperate with the treatment team. In this group it is perhaps best to avoid additional pressure, the obese having already poor self-esteem and being more vulnerable to the feeling of failure.

It requires a dedicated team to provide support and guidance to the obese adolescent. The composition of the team will vary, depending on the facilities available, but it must consist of individuals who are patient, non judgmental, knowledgeable about obesity and human relationships, and want to help the obese lose weight. The patient should realize that there is going to have to be a life-long change in lifestyle and accept the fact that weight loss will not necessarily be dramatic, that there will be "backsliding" at times48 and that it may take an extended period for the desired goal to be achieved.

The basic aim of all the methods of treatment is to induce a negative energy balance49. The methods include partial restriction of intake28-37-38-50. The dietetic prescription must be precise; a dietitian's involvement is essential. Excessive fasting is dangerous and therefore should be avoided51-52. Weight loss must be slow and gradual. It takes about 1 1/2 years of weight maintenance to achieve ideal body weight for each 20% increment in excess of ideal. For the growing teenager, maintaining a steady weight for a period of time (i.e. 6 months, one year) with a balanced diet could be a realistic goal. Energy from fat should not exceed 30%, that from carbohydrates could reach approximately 55% and 15% that from proteins. Daily energy requirements should be calculated, even for fast foods (Table I page 33). For adolescents, whose energy requirements average 2200 kcal (9240 kJ) for girls and 2500 kcal (10500 kJ) for boys, the limit will per 24 hours for girls, 1500 kcal (6500 kJ), 1800 kcal (7500 kJ) for boys per 24 hours. Qualitatively, low-calorie foods and a high intake of fruits, vegetables and grains should be emphasized. There should be a sufficient protein intake. The use of semi total starvation, anorectic drugs53, are contraindicated. The protein-sparing diets are used experimentally as part of an integrated multidisciplinary treatment for obesity54.

It is the health professional's role to warn teenagers about the dangers of "miracle diets". Not only can they be dangerous for their health, but they lack long-term teaching of healthy dietary habits, and inevitably fail. The weight increase which follows is greater than before ("yo-yo" phenomenon) causing a loss of self-esteem and a reluctance to try other therapeutic propositions.

It is important to set some realistic weight loss limits for the overweight adolescent, e.g. about 1/2 -1 lb/week (or ³ 1 kg every 2 weeks). It must also be done with tact in order not to provoke, in the cases of fragile personalities, overly restrictive behaviors such as anorexia nervosa55.

The key feature of any program of treatment of obesity is the need for lifestyle change. Programs that are targeted at both the parents and the adolescents are the most successful in the long run. In most behavioral weight-control programs56, the sessions focus on facilitating adherence to dietary and exercise regimens. This approach has been shown to be most helpful for midly to moderately obese. The energy imbalance that results in obesity has components of under exercising as well as overeating. Thus increased physical activity57-58 that is introduced as part of a program of lifestyle changes should be an integral part of any treatment program59. When the objective is to treat obesity, the prescription should ideally comprise at least 3 or 4 times weekly exercise sessions (e.g. 45 minutes or more of non-stop moderate aerobic activity)60. A regular program of dynamic exercise consumer fat and improves fitness61.

Teenagers and their parents must be referred to a dietitian for dietary advice and follow up. Healthy eating habits must be encouraged over strict diets. In this, parents must be role models.

Prevention

Clearly, prevention of adolescent obesity is desirable since cure is so difficult. Studies of the etiologic factors in adolescent obesity and of the condition's natural history have suggested that obesity starting at age 5 or 6 years is more likely to persist into adolescence and adulthood than that occurring in infancy. The most important risk factor is heredity. If both parents are not obese, there is only a 10% risk of their child being overweight. It is 45% if one of the parents is obese, and 75% if both parents are. Moreover, there is at least 75% chance that an obese adolescent will remain so as an adult. The general practitioner and the pediatrician must identify the patients most susceptible to becoming obese; the main risk factor of obesity is the parents. During routine check-up, they must also identify very early any excessive weight gain tendency.

Considering the low success rate of the various forms of treatment (less than 10%), only prevention is effective. At a very early age62, it is important for the family to:

The anticipatory guidance provided by health professionals, should include advice on good nutrition, giving practical examples such as substitutes for breakfast (yogurts, fruits...)65, as well as emphasizing the importance of eating three meals a day. The young person's misconception that skipping a meal helps to lose weight will have to be demystified. It actually results in the opposite effect, a overeating later in the day and at night.

Conclusion

A multidisciplinary approach that includes counseling the whole family, behavior and lifestyle modification (with emphasis on developing self-esteem), and exercise in addition to dietary management has the best chance of success.

Health professionals including pediatricians, general practitioners, dietitians sometimes teacher66 should promote healthy dietary habits and regular physical activity more aggressively in the community to reduce the risks of future chronic disease. They should work with the broadcast industry to sensitize them about key nutritional issues and their impact on teenagers and to encourage the inclusion of healthy eating messages into programming67.

References

3. Sports and diet

Consideration of the nutritional needs of an adolescent athlete must take into account not only the requirements for normal growth but also the increased requirements for exercise1 (Table I).

The dietary practices of young athletes often fail to meet the energy requirements, threatening their well-being. Furthermore, misconceptions about nutrition are common especially regarding the need for supplements to optimize performance, weight control and training diet. The diet prescriptions to support optimal performance are as varied as the youth and the activities they engage in.

Protein and energy requirements2-3-4

The physical training involved in participation in a sport results in an increase in muscle mass. It has been reasoned that an increased protein intake is necessary to synthesize the additional protein for this increased muscle mass5. It has been suggested that young athletes who are engaged in endurance and resistance training such as bodybuilders or power lifters have protein intakes three to four times the Canadian Recommended Nutrient Intakes (RNI). Such intakes from protein supplements are not only costly, but may theoretically have long-term effects on calcium excretion and kidney function6. Protein requirements for adolescent boys are slightly higher than those for young men, a daily intake of 1.3 to 1.5 g/kg of high-quality animal protein should be sufficient to meet the needs of a young adolescent, male or female, in training especially for endurance and strength exercises7. In a balanced, mixed diet the protein content accounts for approximately 15% of the total energy intake8, with a ratio of animal protein to vegetable protein of 1, to ensure optimal aminoacid requirements.

The energy requirements during adolescence vary from 73 kcal/kg (281 kJ/kg) in a 12-year-old male to 36 kcal/kg (168 kJ/kg) in a 19-year-old female (table I page 5). Depending on the level of activity, adolescents participating in sports may require an additional 600 to 1200 kcal/d (about 2500 to 5000 kJ/d)8-9. Energy expenditure for a variety of physical activities is shown in Table II. Assuming a balanced mixed diet is taken, according to the Canada's Food Guide to Healthy Eating, i.e. 60% from carbohydrate, 15% from protein and 30% from fats, the additional energy intake would add 22 to 45g of protein daily. Clearly, athletes involved in moderate or heavy physical activity who have a balanced diet usually consume more than 2g of protein/kg daily. Therefore, protein supplements are unnecessary.10 Nevertheless, special attention is required for athletes who consume low energy diets (such as ballet dancers, gymnasts, synchro swimmers...), or those on vegan or fad diets.

Table 1. Average Energy Allowances* of adolescents based on Age, Weight and Level of Physical Activity
Age (years) and Sex Activity Level
. Light Moderate Heavy
10 both 57 70 86
11-14 M 44 55 66
15-18 M 37 46 55
11-14 F 37 46 55
15-18 F 33 40 48
*Kilo calories per kilo of body weight/day
Adapted from Recommended Dietary Allowances, 1989 by the National Academy of Sciences, National Academy Press, Washington DC.