The Active Female: Health Issues Throughout the Lifespan 2008th Edition

29. Nutritional Guidelines and Energy Needs for the Female Athlete: Preventing Low Energy Availability and Functional Amenorrhea Through Diet

Jacalyn J. Robert-McComb  and Ángela García González 

(1)

Department of Health, Exercise, and Sport Sciences, Texas Tech University, 3204 Main Street, Lubbock, TX 79409, USA

(2)

Pharmaceutical and Food Sciences, University San Pablo-CEU, Urb. Montepríncipe; Ctra. Boadilla del Monte km 5.3, Madrid, 28668, Spain

Jacalyn J. Robert-McComb (Corresponding author)

Email: jacalyn.mccomb@ttu.edu

Ángela García González

Email: angargon@fusp.ceu.es

Abstract

The prevalence of secondary amenorrhea, in athletes, varies widely with sport, age, training volume, and body weight. Studies over different athlete populations report rates of menstrual disorders ranging from 1 to 69 % and of 70 % for subclinical ovarian disturbances in athletes, while, on the other side, only about 2–15 % of sedentary youth women have menstrual irregularities. Studies showed that normal menstrual cycling is altered if there is a restriction in energy availability, that is, the amount of dietary energy remaining for other body functions after exercise training. When energy availability is too low, physiological mechanisms reduce the amount of energy used for cellular maintenance, thermoregulation, growth, and reproduction. This compensation tends to restore energy balance and promote survival but impairs general health. Studies consistently show that female athletes are not consuming enough energy to support their activity levels, and low energy and nutrient intake places these athletes at a greater risk for nutrition-related disorders such as amenorrhea, osteoporosis, iron-deficiency anemia, and eating disorders. This is not just a problem for those athletes that practice sports with a thigh weight control but for all women practicing high-level sports. So, individual nutritional assessment and dietetic advice are pillars for maintaining health and good performance. Nutritional educational projects must be carefully designed by a multi-professional team and should involve not only the sportive women but also coaches and family to be successful in facilitating athletes the right skills for adopting healthy eating habits. A joint position statement by the American College of Sports Medicine, the American Dietetic Association, and the Dietitians of Canada states that a diet substantially different from that recommended in the Dietary Guidelines for Americans is not needed for athletes, once enough calories are ingested to meet their energy needs. It is recommended that an athlete’s diet should consist of nutrient-dense food and beverages within and among the basic good groups while choosing foods that limit the intake of saturated and trans fats, cholesterol, added sugars, salt, and alcohol.

Keywords

Functional hypothalamic amenorrheaFemale athlete triadEnergy availabilitySecondary amenorrheaDietary guidelines for Americans

After completing this chapter, you should have an understanding of the following:

·               The term female athlete triad (Triad) and functional hypothalamic amenorrhea (FHA)

·               The energy availability hypothesis and FHA

·               Energy and nutritional intake estimations

·               Nutritional guidelines for the female athlete

·               The importance of hydration before, during, and after exercise

29.1 Introduction

Studies have repeatedly shown that endurance female athletes do not take in enough calories to meet the exercise challenges they have imposed on their body. Energy deficiency (either intentional or unintentional) may emerge through extreme exercise energy expenditure (EEE) alone, if it is not accompanied by a commensurate increase in energy intake. Even moderate dietary restriction and moderate EEE may result in energy deficiency. In this chapter, we review the research that has focused on the female athlete and a triad of disorders related to insufficient energy intake. Specifically we focus on energy availability and functional amenorrhea. We also discuss the dietary needs of the female athlete to prevent the cascade of disorders.

29.2 Research Findings

Both dietary restriction and exercise diminish the availability of utilizable fuels for body functions. During extended periods of deficient metabolic fuel, the body sustains functions necessary for life by diverting scarce metabolic fuels to essential cellular maintenance: The less critical functions not necessary for individual survival, such as reproductive function, are compromised [1]. A longitudinal pattern of disorders in the young athletic female population has been observed. Noteworthy is that the observed disorders may not be considered clinical or even subclinical to be harmful to the long-term health of the athlete. These behaviors have been observed in recreational athletes as well as elite athletes [23]. There seemed to be a relationship among the disorders that had an effect on reproductive function in the short term and possible osteoporosis later in life. It was thought that one disorder led to another disorder. This pattern of disorders had a domino effect and has been referred to as a cascade of disorders.

In 1992, the term female athlete triad (Triad) was coined to describe three distinct but frequently interrelated disorders found in the female athletic population. These components were disordered eating, amenorrhea, and osteoporosis. In 2007, the American College of Sports Medicine redefined the Triad in terms of the physiological mechanisms by which low energy availability caused functional hypothalamic menstrual disorders and low bone mineral density [4].

It is now understood that low energy availability can occur with or without disordered eating and that other kinds of menstrual disorders are excluded from the Triad. The menstrual disorder referred to in the Triad is known as functional amenorrhea. For the female athlete, the term FHA is used because it is a functional problem, not an anatomical one (i.e., altered hormonal patterns, rather than an anatomical problem), and it is reversible [56].

Although the definitions of amenorrhea are somewhat arbitrary, amenorrhea can be described as primary or secondary. Primary amenorrhea (delayed menarche) is the absence of menstruation by age 15 in a girl with secondary sex characteristics [7]. Secondary amenorrhea is the absence of three or more consecutive menstrual cycles or a period of 3 months without menses after menarche or after cycles have been established [7].

The prevalence of secondary amenorrhea, in athletes, varies widely with sport, age, training volume, and body weight. Studies over different athlete populations report rates of menstrual disorders ranging from 1 to 69 % and of 70 % for subclinical ovarian disturbances. On the other side, studies show that only about 2–15 % of sedentary youth women have menstrual irregularities [814].

Warren (1980) was the first to suggest that menstrual disorders in female athletes are caused by an energy drain [15]. Winterer et al. (1985) hypothesized that failure to provide sufficient metabolic fuels to meet the energy requirements of the brain causes an alteration in brain function that disrupts the gonadotropin-releasing hormone (GnRH) pulse mechanism [16]. Reproductive function critically depends on the pulsatile release of GnRH from GnRH neurons in the arcuate nucleus of the hypothalamus and on the consequent pulsatile release of luteinizing hormone (LH) from the pituitary [17]. Figure 29.1depicts the biochemical axis for menses to occur. This axis is known as the hypothalamus-pituitary-ovarian axis.

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Fig. 29.1

Hypothalamus-pituitary-ovarian axis

In the athletic female, energy drain can occur either by not taking in enough calories to meet the metabolic needs of the body or by over-exercising and not compensating for the energy cost of the exercise by taking in additional calories. A series of well-controlled studies by Loucks at Ohio University demonstrated that normal menstrual cycling was altered if there is a restriction in energy availability [11720]. Energy availability (EA) was defined by Loucks as dietary energy intake (DEI) minus EEE. Perhaps it could be paraphrased by stating that EA is the amount of dietary energy remaining after exercise training for other functions of the body such as cellular maintenance, thermoregulation, growth, and reproduction. When EA is too low, physiological mechanisms reduce the amount of energy used for cellular maintenance, thermoregulation, growth, and reproduction. This compensation tends to maintain energy balance (by slowing down metabolism, etc. and not providing energy for noncritical functions such as reproduction) and promote survival but impairs general health [8]. It should be noted that energy availability (DEI − EEE) is not the same as energy balance. Energy balance is defined as DEI minus total energy expenditure (heat from all cellular functions), not just EEE. Energy availability is much simpler to estimate and requires less expensive equipment, and so the term is a more practical term.

For the female athlete who does not take in enough calories, either intentionally or unintentionally, behaviorally controlled restricted dietary energy intake has an effect on the cellular availability of oxidizable metabolic fuels and reproductive function such as glucose [6]. Glucose is an important metabolic fuel needed for maintenance of bodily functions and survival.

The adult female human brain oxidizes approximately 80 g of glucose each day at a continuous rate, and this must be provided daily by dietary carbohydrate, because the brain’s rate of energy expenditure can deplete liver glycogen stores in less than 1 day [21]. Moderate exercise oxidizes that much glucose in an hour [17]. On the basis of respiratory quotients measured during exercise training, 62–88 % of the energy expended during exercise was derived from carbohydrates, principally glucose [20]. Thus, the special demand that aerobic exercise places on glucose stores suggests that the failure of women to sufficiently increase dietary glucose intake, specifically, in compensation for the energy cost of the exercise may lower glucose availability to the brain below a critical threshold necessary for the normal neuroendocrine function of the thyroid, reproductive, and other endocrine axes [22].

Interestingly, Loucks et al. found that EEE may compromise brain glucose availability less than the corresponding amount of dietary energy restrictional one [1]. In their experiment, they found that skeletal muscle derived much less energy from carbohydrate oxidation in the deprived energy availability treatment than in the balanced energy availability treatment (49 versus 73 %) [1]. This alteration in fuel utilization during the deprived energy state conserved approximately 70 % of the brain’s daily glucose requirement. Their conclusion from this study was that prolonged exercise had no disruptive effect on LH pulsatility in women—apart from the impact of its energy cost on energy availability or glucose availability. As stated earlier, reproductive function critically depends on the pulsatile release of GnRH from GnRH neurons in the arcuate nucleus of the hypothalamus and on the consequent pulsatile release of LH from the pituitary [17]. Please refer to Fig. 29.2 for a visual understanding of the menstrual cycle and the importance of the pulsatile release of LH.

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Fig. 29.2

Patterns of hormone secretion across the normal menstrual cycle. An LH surge occurs at the time of ovulation and marks the division between the follicular phase (days 1–14) and the luteal phase (days 15–28). LH pulse paternal, so changes across the menstrual cycle; pulse frequency decreases from the follicular phase (−65- to 80-min intervals) to the luteal phase (−185- to 200-min intervals), whereas pulse amplitude increases from the follicular phase (−5 miU/mL) to the luteal phase (−12 miU/mL)

The inference from Louck’s study was that LH pulsatility was disturbed less by EEE than by dietary energy restriction alone [1]. The basis of this inference was the demonstration that during exercise, muscles altered carbohydrate fuel utilization by 33 % during a deprived energy state as opposed to a balanced energy state (73 % balanced energy state versus 49 % energy-deprived state).

In a subsequent study, Loucks and Thuma found that LH pulsatility was disrupted abruptly at a threshold of energy availability less than 30 kcal/kg of lean body mass per day (LBM·d) [17]. The subjects in their experiment were regularly menstruating, habitually sedentary young women of normal body composition. Interestingly, they found that there were thresholds for physiological functioning to be impaired; the relationship between energy availability and altered hormonal and metabolic responses was not linear. Importantly, not all females had the same threshold for energy availability; but if this threshold fell below a critical threshold, hormonal alterations would result.

They found that the incremental effects of restricted energy availability on LH pulse frequency and amplitude most closely resembled the incremental effects of restricted energy availability on metabolic substrates and hormones such as plasma glucose, cortisol, 3-hydroxybutyrate (beta HOB), and growth hormone. Worth mentioning is that this association did not imply that any of the metabolic substrates and hormones were involved in the mechanism mediating the effects of energy availability on LH pulsatility.

If energy availability was approximately 30 kcal/kg LBM·d, the responses of various metabolic hormones (insulin, cortisol, IGF-I/IGFBP-1/IGHBP-3/leptin, and T3) maintained plasma glucose levels to within 3 % of normal. Many of these hormones block glucose entry into the cell to maintain a normal glucose level. Conversely, leptin and triiodothyronine (T3) were substantially suppressed by a restricted energy availability of 30 kcal/kg LBM·d; T3was further depressed by a reduction in energy availability of 20 kcal/kg LBM·d. Triiodothyronine is a thyroid hormone that plays vital roles in the body’s metabolic rate, heart and digestive functions, muscle control, brain development, and maintenance of bones. Leptin is a hormone that plays a key role in regulating energy intake and energy expenditure, including appetite and metabolism. It is one of the most important adipose-derived hormones.

They also found that the disruptive effects of subthreshold energy availability were bimodal or appearing as two distinct peaks, with substantially larger effects occurring in subjects with the shortest luteal phases. Their results suggested that women with short luteal phases (11 days) might be at a higher risk than others for the suppression of ovarian function and skeletal demineralization by energy deficiency.

29.3 Contemporary Understanding of the Issues

29.3.1 Energy Availability and Functional Amenorrhea

As illustrated in Fig. 29.3, reproductive function may be altered at the level of the hypothalamus because of energy drain, insufficient energy availability, or negative energy balance. More than one term has been used in the literature to present the same concept. More simply stated, it could be called energy or nutritional stress. Stress may even be psychological for reproduction to be altered from stress; however, in this chapter, we are focusing on insufficient energy availability. In this illustration, GnrH is not released at the level of the hypothalamus because of activation of the hypothalamic-pituitary-adrenal (HPA) axis. This axis is sometimes called the stress axis. The diagram depicts activation of the HPA axis in which the hypothalamus releases corticotropin-releasing hormone (CRH) which inhibits GnRH and suppresses the hypothalamic-pituitary-gonadal (HPG) axis. Ultimately LH pulsatility is affected if energy availability falls to a certain threshold or if there is a very low negative energy balance [17]. Menses then ceases resulting in what is termed or simply functional amenorrhea or more precisely FHA. FHA is defined as a nonorganic and reversible disorder in which the impairment of GnRH pulsatile secretion plays a key role in LH pulsatility. LH pulsatility can be suppressed by a combination of strenuous exercise and caloric restriction [1]. There is a threshold of energy availability, roughly 30 kcal/kg LBM·d for most women, that must be met for normal menstrual cycling. The threshold of energy availability is not the same for all women: But if that threshold is met, the restoration of cycling will occur if previously energy deficient and functionally oligo/amenonrrheic [17]. So functional amenorrhea as termed in the Triad of disorders is reversible if the individual’s threshold for energy availability is met, which seems to be roughly 30 kcal/kg LBM·d [18].

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Fig. 29.3

Suppression of the hypothalamic-pituitary-ovarian (HPO) axis. Axis (HPO) from energy stress by the hypothalamic-pituitary-adrenal (HPA) axis

29.3.2 Hormonal Regulation of Food Intake

Food intake and energy expenditure are regulated centrally and peripherally by a plethora of hormones and neuropeptides. The role of some gut hormones, such as ghrelin or peptide YY and adipose-derived hormones such as leptin, on eating control after exercise practice has recently been investigated [2327]. Figure 29.4 graphically illustrates the role of these hormones in appetite control.

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Fig. 29.4

Neural control of appetite

Ghrelin is a unique circulating peripheral orexigenic hormone that is currently being investigated and deserves attention [28]. Ghrelin is a gastrointestinal hormone secreted by endocrine cells in the stomach. It can cross the blood–brain barrier and activate special receptors in the arcuate nucleus in the hypothalamus of the brain leading to a cascade of processes that end in an increase in hunger and food intake. Through this central mechanism (crossing the blood barrier and activating receptors in the brain), ghrelin has been proposed to play a role in short-term energy homeostasis.

Conflicting findings have been reported regarding exercise training on ghrelin release: (a) some studies found no changes in ghrelin levels after the practice of sport [2429]; (b) some studies found a transitional suppression of the acylated form of the hormone [2430], the form of the hormone thought to be responsible for appetite stimulation [28]; (c) while other studies found some increase in ghrelin [2331]. Yet, even the studies that reported increases in ghrelin ciphers in exercising women with functional amenorrhea, found no subsequent increase in appetite or food intake, a fact which may be hypothetically due to some degree of ghrelin resistance [31].

Intense exercise expenditure (without a compensatory intake in calories) is able to induce a short-term negative energy balance during vigorous exercise, a phenomenon that has been described as “exercise-induced anorexia” [242532]. Even if ghrelin is secreted, which should signal hunger, there are opposing hormones that are secreted when there is a negative energy balance. If ingestion is not enough to compensate the EEE, we will find a relative negative energy balance, and this negative energy balance will induce pancreatic peptide YY (PYY) release which in turn will induce satiety and less hunger sensation. This phenomenon may be associated with some other molecules in addition to PYY such as glucagon-like peptide-1 (GLP-1) [23].

There has been a marked increase in our understanding of the importance of gut hormones in the regulation of energy homeostasis.

Pancreatic PYY is a hormone which is secreted from endocrine cells called L-cells in the small intestine. It can also cross the blood barrier and act centrally in the control of food intake decreasing hunger and thus food intake. PYY is released after eating, circulates in the blood, and works by binding to receptors in the brain. These receptors then cause a decreased appetite and make people feel full after eating. PYY also acts in the stomach and intestine to slow down the movement of food through the digestive tract. Pancreatic PYY concentrations rise postprandial in proportion to caloric intake and stay elevated for several hours while fasting. Concentrations are regulated by general caloric intake and negatively correlated with body mass index, suggesting a role of this molecule in long-term energy homeostasis [33].

Additionally, because of the observed changes in the levels of gastrointestinal hormones in women with functional amenorrhea and because their receptors are closely related with the hypothalamic-pituitary-ovarian axis, some authors have hypothesized a direct role of gastrointestinal hormones in the etiology of functional amenorrhea although more studies are needed to determine the exact role of ghrelin, PYY, and adipokines in this pathology [2334]. GLP-1 is a hormone produced in the intestinal epithelial endocrine L-cells: GLP-1 is released in response to meal intake. The main actions of GLP-1 are to stimulate insulin secretion and to inhibit glucagon secretion. It also appears to be a physiological regulator of appetite and food intake. Decreased secretion of GLP-1 may contribute to the development of obesity, and exaggerated secretion may be responsible for postprandial reactive hypoglycemia.

In conclusion, during extended periods of reduced energy availability, the body prioritizes by fueling the activities necessary for survival such as thermoregulation and locomotion; therefore, less critical processes such as reproductive function may be compromised. The restoration of normal menstrual cycling has been demonstrated to reoccur when the individual’s threshold for energy availability is sequentially met [18]. However, observations suggest that appetite may be an inadequate indicator of energy balance during athletic training, just as thirst is an insensitive indicator of water balance during athletic competition. Athletes may need to eat by discipline rather than by appetite during training to prevent reproductive disorders [1].

29.3.3 Estimating Energy and Nutritional Intake

Studies consistently show that female athletes are not consuming enough energy to support their activity level [3538]. Research with elite female swimmers, using the doubly labeled water technique, noted that total daily energy increased to 5,593 kcal daily during high-volume training. This is the highest caloric expenditure of female athletes reported [39]. However, their intake averaged only 3,136 kcal, implying a negative energy balance. Energy intake of well-trained female athletes ranges from 1,931 to 3,573 kcal [40]. Consequently, their intake of essential vitamins and minerals is lower than the recommended daily allowance [41]. Female athletes’ diets have been found to be low in iron, calcium, zinc, vitamin D, vitamin B6, and folate [42].

Low energy and nutrient intake places these athletes at a greater risk for nutrition-related disorders such as amenorrhea, osteoporosis, iron-deficiency anemia, and eating disorders [3538]. It must be emphasized that all women participating in high-level competitive sports must remain vigilant and take in enough calories to meet their energy demands. It is not only athletes who practice sports with tightly regulated weight control practices who are at risk of suffering the complications of the Triad. All female athletes must have an awareness of the importance of adequate caloric intake to meet energy demands.

Traditionally, recommendations for energy requirements have been based on self-recorded estimates (e.g., diet records) of food intake. However, it is thought that these records are misleading [4]. The percentage of people who underestimate their food intake ranges from 10 to 45 % [43]. Since the advent of the doubly labeled water technique for measuring total energy expenditure, scientists have established energy requirements based on the actual measurement of total energy expenditure in free-living individuals [4]. It has been found that some of the commonly used formulas, such as the Harris–Benedict Equation, to estimate energy requirements are not accurate and underestimate or overestimate requirements [4445].

The Mifflin–St Jeor equation is more likely than other equations to estimate RMR within 10 % of the measured and is estimated from weight, height, and age [46]. Multiple-regression analyses were employed to drive relationships between RMR and weight, height, and age for both sexes (R2 = 0.71), but separation by sex did not affect its predictive value. RMR = 9.99 × weight (kg) + 6.25 × height (cm) − 4.92 × age (year) +166 × sex (males, 1; females, 0) − 161 [47]. The Mifflin–St Jeor formula can be found in Table 29.1.

Table 29.1

An estimated energy expenditure prediction equation using the Mifflin–St. Jeor equation to determine resting metabolic rate

Step 1: Estimate resting metabolic rate (RMRusing the Mifflin–St. Jeor equation

RMR = 9.99 × weight (kg) + 6.25 × height (cm) − 4.92 × age (year) + 166 × sex (males, 1; females, 0) − 161

Step 2: Determine additional caloric requirements based on level of activity

Physical activity level

Percentage above resting level

Bed rest

10

Quiet rest

30

Light activity

40–60

Moderate activity

60–80

Heavy activity

100

Additional caloric requirements = RMR × percentage above resting level

Step 3: Determine predicted total energy expenditure (TEE)

TEE = RMR + additional caloric requirements based on activity

Adapted from physiology of fitness (3rd ed.) (p. 359) by B. J. Sharkey, 1990, Champaign, IL: Human Kinetics

The information at the US Department of Agriculture (USDA) National Agricultural Library (NAL) website is quite amazing and very helpful. The Food and Nutrition Information Center (FNIC), located at the USDA NAL is a leader in online global nutrition information including caloric expenditure equations for specific populations. The FNIC website contains over 2,500 links to current and reliable nutrition information. The FNIC provides links to the Dietary Reference Intake (DRI) tables and reports developed by the Institute of Medicine’s Food and Nutrition Board. Appendices 12, and 3 contain a list of the valuable information that you can assess at http://​fnic.​nal.​usda.​gov/​dietary-guidance. The information on this website provides sound nutritional guidance and assessment tools for evaluation. The tools provided on this site are interactive, and there is no charge for them. In fact the government encourages people to use them especially in light of the problems with healthy weight maintenance issues for all people. The Institute of Medicine (IOM) has developed caloric expenditure equations depending on activity level, gender, and age.

Recommendations for caloric intake to maintain weight will vary depending on a person’s age, sex, size, and level of physical activity and are provided in the DRI for energy carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids [13]. Tables 29.2 and 29.3 list these equations for females only. The DRI for energy carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids complete document can be downloaded free of charge in a PDF file (http://​fnic.​nal.​usda.​gov/​dietary-guidance/​dietary-reference-intakes/​dri-reports). This report is very helpful, and we would encourage you to download the PDF chapter. Appendix 4 also gives estimated caloric needs based on activity levels from the IOM.

Table 29.2

Physical activity level (PAL) index and physical activity coefficient (PA) used to derive estimated energy requirements (EER) for women

PAL

Sedentary (1.0–1.39)

Low active (1.4–1.59)

Active (1.6–1.89)

Very active (1.9–2.5)

 

Typical daily living activities (e.g., household tasks, walking to the bus)

Typical daily living activities + 30–60 min of daily moderate activities (e.g., walking at 5–7 km/h)

Typical daily living activities + at least 60 min of daily moderate activities

Typical daily living activities + at least 60 min of daily moderate activities and an additional 60 min of vigorous activity or 120 min of moderate activity

PA at 4 levels

PA (level 1)

PA (level 2)

PA (level 3)

PA (level 4)

Girls 3–18 years

1.00

1.16

1.31

1.56

Women 19 years+

1.00

1.12

1.27

1.45

PAL physical activity level or physical activity index, PA physical activity coefficient

Adapted from A Report of the Panel on Macronutrients, Subcommittees on Upper Reference Levels of Nutrients and Interpretation and Uses of Dietary Reference Intakes, and the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes. Dietary reference intakes for energy carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients). Washington DC: National Academy Press; 2005

Table 29.3

Equations to estimate energy requirement

Children and adolescents 3–18 years

Estimated energy requirement (kcal/day) = Total energy expenditure + energy deposition

Girls

38 years

EER = 135.3 − (30.8 × age [year]) + PA × [(10.0 × weight [kg]) + (934 × height [m])] + 20

918 years

EER = 135.3 − (30.8 × age [year]) + PA × [(10.0 × weight [kg]) + (934 × height [m])] + 25

Adults 19 years and older

Estimated energy requirement (kcal/day) = Total energy expenditure

Women

EER = 354 − (6.91 × age [year]) + PA × [(9.36 × weight [kg]) + (726 × height [m])]

Pregnancy

Estimated energy requirement (kcal/day) = Nonpregnant EER + Pregnancy energy deposition

1st trimester

EER = Nonpregnant EER + 0

2nd trimester

EER = Nonpregnant EER + 340

3rd trimester

EER = Nonpregnant EER + 452

Lactation

Estimated energy requirement (kcal/day) = Nonpregnant EER + Milk energy output − Weight loss

0–6 months postpartum

EER = Nonpregnant EER + 500 − 170

7–12 months postpartum

EER = Nonpregnant EER + 400 − 0

Note: These equations provide an estimate of energy requirement. Relative body weight (i.e., loss, stable, gain) is the preferred indicator of energy adequacy

EER estimated energy requirement, PA physical activity coefficient

Note: See Table 32.​2 to find the appropriate PA value to use in these equations

Adapted from A Report of the Panel on Macronutrients, Subcommittees on Upper Reference Levels of Nutrients and Interpretation and Uses of Dietary Reference Intakes, and the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes. Dietary reference intakes for energy carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients). Washington DC: National Academy Press; 2005

Although a self-reported food nutritional assessment may misrepresent total caloric intake because of underreporting, it does provide valuable information to aid in nutritional counseling. Table 29.4provides guidelines for an exercise nutritionist to help physically active individuals, particularly competitive athletes, achieve energy balance. These guidelines are from the American College of Sports Medicine, the American Dietetic Association, and the Dietitian of Canada Joint Position Statement [48].

Table 29.4

How exercise nutritionists can help female athletes maintain energy balance

Athletes should be educated about energy requirements for their sport and the role of food in fueling the body. Female athletes should be educated about the female athlete triad and the long-term health consequences of inadequate energy intake. Unrealistic weight and body composition goals should be discouraged.

The athlete’s typical dietary and supplement intake during training, competition, and the off-season should be assessed. This assessment should be used to provide appropriate recommendations for energy and nutrient intakes for the maintenance of good health, appropriate body weight and composition, and optimal sport performance throughout the year.

Body size and composition of an athlete should be assessed for the determination of an appropriate weight and composition for the sports in which she participates. Since athletes come in all shapes and sizes, girls and women must be allowed to and encouraged to choose sports appropriate for their natural body type. Minimum body composition for good health for the female athlete is 12 %. Provide the athlete with nutritionally sound techniques for maintaining an appropriate body weight and composition without the use of severe diets or nutritionally unbalanced macronutrient choices.

The fluid intake and weight loss of athletes during exercise should be assessed. Appropriate recommendations regarding total fluid intake before, during, and after exercise should be made based on this assessment and the most current scientific literature.

Carefully evaluate any vitamin/mineral or herbal supplements, ergogenic aids, or performance-enhancing drugs an athlete wants to use. These products should be used only after a careful review of their legality and the current literature pertaining to the ingredients listed on the product label. Caution should be used in recommending these products and should only be recommended after evaluating the athlete’s health, diet, nutrition needs, current supplement and drug use, and energy requirements.

Source: Adapted from the American College of Sports Medicine, American Dietetic Association, Dietitian of Canada. Joint Position Statement. Nutrition and Athletics Performance. Med Sci Sports Exerc 2009 4183):709–731

A nutritional assessment consists of collecting and evaluating a number of types of information. These include a brief patient history; results of a physical examination (performed by a physician); anthropometric data such as height, weight, body mass index, and percentage body fat; and finally, some biochemical data that are obtained through blood evaluation. This laboratory testing focuses on serum proteins such as albumin, prealbumin, and retinol-binding protein; creatinine height index; and overall immune status. The initial review process serves a number of functions. It allows for the identification of nutritional and medical risk factors, existing nutritional deficiencies, and past nutritional problems.

The next step is a dietary assessment. The purpose of the dietary assessment is to identify a person’s eating habits and to estimate their average daily nutrient intake. Through a variety of methods, information should be obtained on the amount and variety of foods eaten. The simplest method of assessment is to have the individual keep a daily dietary intake record. Because intake tends to vary from day to day, a 3-day food record is more accurate than the 24-h recall. Many nutritionists even recommend a 7-day food record. The dietary intake recording is more accurate if the recalled period is longer. However more cooperation and collaboration are needed. Based on experience, the optimum dietary evaluation recall should be 4 days in length, which should include a holiday (weekend day). If a longer period is needed for more information about the intake of special micronutrients, a 4-day period should be repeated as many times as needed in order to have the required length of time for the analysis. This method allows the practitioner to be able to gather information about changes in food habits because of season ability [49]. However, methods only reflect the person’s current diet, not eating habits, established over a long period of time. It is important to recognize that self-reported estimates of food intake are biased and many times do not provide an accurate estimation of food intake; therefore, these should only be used as a guide. A food frequency questionnaire is also helpful to determine eating habits. Appendices 5 and 6 provide examples of nutrition and food frequency questionnaires, respectively, that can be used to gather information.

If the practitioner or the athlete has access to the Internet, there is actually no need to buy a computer program to assess nutritional adequacy. However, nutritional programs should be used for an athlete’s diet. As stated earlier in the chapter, dietary assessment tools can be found at the USDA NAL FNIC at http://​fnic.​nal.​usda.​gov/​dietary-guidance/​dietary-assessment. The tools at this site range from a nutritional analysis tool to an activity calorie counter. There is also a behavior change and educational maintenance tool for Web-based learning for the practitioner. For a complete list of available tools at this site go to Appendix3 .

If there is a need to install a dietary assessment tool on a lab or a personal computer, there are numerous nutritional assessment software programs on the market—most are under $60.00. Most of these programs contain more than 23,000 food items and are upgradable to allow new food items to be entered by the user. One such program is the Diet Analysis Plus 9.0 Windows/Macintosh CD-ROM, 9th Edition from Cenege Learning. This program allows for a 7-day food intake per individual. It takes into account height, weight, and activity level. It also computes daily and weekly values for recommended daily allowance (RDA) and energy expenditure. In addition, it gives a fairly specific breakdown of nutrients and has the ability to generate graphs, charts, and reports. These programs allow a nutritional novice to enter their own data concerning their individual diet and nutrition and receive easy-to-understand information. The use of nutritional assessment software is relatively widespread because of its low cost and availability. Many of these tools and online programs are perfect devices for coaching young women to be aware of their nutritional and caloric needs.

Even though the determination of energy needs is relatively straightforward, behavior change is complex and not so readily understood. Nutritional educational projects must be carefully designed by a multi-professional team to be successful in facilitating athletes to change their behavior [145052]. The education should involve not only the sportive women but also coaches and family so that skills are learned for adopting healthy eating habits.

In Chapter 14, the authors discuss the available evidence-based disordered eating programs for active females. Appendix 7 lists resources for helping athletes with eating disorders or even disordered eating patterns which may progress to an eating disorder. If the athlete is exhibiting signs and symptoms of energy imbalance, such as weight loss, amenorrhea, loss of concentration, and irritability, the athlete should be encouraged to seek professional counseling.

29.4 Future Directions

29.4.1 Nutritional Guidelines for the Female Athlete

29.4.1.1 Priority is Meeting Energy Needs

Meeting energy needs is the first priority for the female athlete. Studies consistently state that female athletes do not take in enough calories. Despite the known causal relation between low energy availability and menstrual disturbances, appropriate practical guidelines for the optimal balance of dietary intake and EEE (to maintain correct ovarian function) in exercising women remain undefined. Energy balance is defined as a state when energy intake (the sum of energy from foods, fluids, and supplement products) equals energy expenditure (the sum of energy expended as basal metabolism, thermal effect of food, and any voluntary physical activity). Current efforts to review this issue and provide a set of guidelines for athletes and physically active women are under way by the Female Athlete Triad Coalition, an international consortium of professionals dedicated to optimizing the health of female athletes. Updated information for general public and professionals can be found in their website (http://​www.​Femaleathletetri​ad.​com). Table 29.5 shows some hints for athletes to maintain optimal energy intake [8].

Table 29.5

Recommendations to get enough energy for active women

Balance calories

Enjoy your food but eat less. Be aware of hunger and fullness cues. Avoid oversize portions

Make half your plate fruits and vegetables

Switch to fat-free or low-fat milk and dairy products

Make half your grain whole grains

Cut back on foods high in solid fats, added sugar, and salt

Choose low-sodium products. Read nutritional labels

Drink water instead of sugary drinks

Nattiv A., Loucks AB., Manore MM., Sanborn CF, Sundgot-Borgen J., and Warren MP. American College of Sports Medicine. Position Stand. The Female Athlete Triad. 2007. Med Sci Sports Exerc Oct;39(10):1867–82

29.4.1.2 Micronutrients for Athletes

Research in exercise nutrition indicates that the large number of teenagers and adults, including competitive athletes, who exercise regularly to keep fit do not require additional nutrients beyond those obtained through the regular intake of a nutritionally well-balanced diet if energy needs are being met [40]. A joint position statement by the American College of Sports medicine, the American Dietetic Association, and the Dietitians of Canada stated that a diet substantially different from that recommended in the Dietary Guidelines for Americans or the Nutrition Recommendations for Canadians (55–58 % of energy from carbohydrate, 12–15 % of energy from protein, and 25–30 % of energy from fat) is not needed for athletes [53]. It is generally recommended that an athlete’s diet should be composed of approximately 55–60 % carbohydrate, 20–25 % fat, and 12–15 % protein [5354]. Nevertheless, some experts in sports nutrition recommend broader ranges of the macronutrients depending on the needs of the athlete [40].

The Dietary Guidelines for Americans is published jointly every 5 years by the Department of Health and Human Services (HHS) and the USDA. The 2010 Dietary Guidelines for Americans can be downloaded at http://​www.​cnpp.​usda.​gov/​DGAs2010-PolicyDocument.​htm [55]. The Dietary Guidelines describe a healthy diet as one that emphasizes fruits, vegetables, whole grains, and fat-free or low-fat milk and milk products; includes lean meats, poultry, fish, beans, eggs, and nuts; and is low in saturated fats, trans fats, cholesterol, salt (sodium), and sugar [3556]. Although there are general food group categories, there are specific recommendations based on age, gender, and activity level.

The USDA SuperTracker (https://​www.​choosemyplate.​gov/​SuperTracker/​default.​aspx) provides online tools that aid and allow one to customize according to age, gender, and physical activity level. Day-to-day caloric intakes as well as physical activity patterns can be tracked using the SuperTracker. Table 29.6 summarizes the recommendations for a healthy diet according to Choose my Plate (USDA) for a standard active female of 25 years.

Table 29.6

Example of specific recommendations for physically active females from 19 to 30 years from the US Department of Health and Human Services and the US Department of Agriculture, Dietary Guidelines for Americans.

Calories

Allowance

   

Total calories

2400 per day

   

Empty calories

<330 per day

   

Food group

Food group amount

“What counts as”

Tips

Grains

8 ounces per day

1 ounce of grains equals:

Eat at least half of all the grains whole grains (4 ounces)

   

1 slice of bread

 
   

½ cup of cooked pasta, rice, or cereal

 
   

1 tortilla

 
   

1 pancake

 
   

1 ounce ready to eat cereal

 

Vegetables

3 cups per day

1 cup of vegetables equals:

Include vegetables in meals and snacks

Dark green

2 cups per week

1 cup raw or cooked vegetable

Add dark-green, red, and orange vegetables to main and side dishes

Red and orange

6 cups per week

1 cup 100 % vegetable juice

Beans and peas are great source of fiber; add them to salads, soups, and dishes or serve as a main dish

Beans and peas

2 cups per week

2 cup leafy salad green

 

Starchy

6 cups per week

   

Other

5 cups per week

   

Fruits

2 cups per day

1 cup of fruit equals:

Select fresh, frozen, canned, and dried fruit more often than juice

   

1 cup raw or cooked fruit

Maximize taste and freshness by adapting your choice to what’s in season

   

1 cup 100 % fruit juice

Use fruits as snacks or dessert; add them to salads

   

¼ dried fruit

 

Dairy

3 cups per day

1 cup dairy

Drink fat-free or low-fat milk and yogurt

   

1 cup milk

When selecting cheese choose reduced fat versions

   

1 cup fortified soymilk

 
   

1 cup yogurt

 
   

1 ½ ounces natural cheese

 
   

2 ounces processed cheese

 

Protein foods

6 ½ ounces per day

1 ounce of protein foods equals:

 

Seafood

10 ounces per week

1 ounce lean meat, poultry, or seafood

Eat a variety of food from the protein group each week

   

1 egg

Eat more seafood than meat or poultry

   

1 tablespoon peanut butter

Select lean meat and poultry. Trim or drain fat from meat and remove

   

½ ounce nuts or seeds

Poultry skin

   

¼ cup beans or peas

 

Oil

7 teaspoons per day

1 teaspoon of oil equals:

Choose soft margarines with zero trans fat made from liquid vegetable oil

   

1 tsp vegetable oil

Use vegetable oils rather than solid fats

   

1 ½ tsp mayonnaise

 
   

2 tsp tube margarine

 
   

2 tsp French dressing

 

Example of personal plan designed using the SuperTracker tool from the USDA (https://​www.​choosemyplate.​gov/​SuperTracker/​default.​aspx) for a woman 25 years old, with BMI of 23 and who practices more than 60 min of moderate physical activity per day

A basic premise of the Dietary Guidelines is that food guidance should encourage individuals to achieve the most recent nutrient intake recommendations of the IOM, referred to collectively as the DRIs. Tables of the DRIs are provided for all age groups and can be found at the USDA NAL website at http://​fnic.​nal.​usda.​gov/​dietary-guidance/​dietary-reference-intakes [57].

These nutrient intake levels should be achieved if there is a balance of macronutrients (approximately 55–60 % carbohydrate, 20–25 % fat, and 12–15 % protein) in the female athlete’s diet and the foods that are chosen are nutrient dense.

Even though the fuel burned during exercise depends on the intensity and duration of the exercise, the sex of the athlete, and prior nutritional status, an increase in the intensity of the exercise will increase the contribution from carbohydrate. A low-carbohydrate diet rapidly compromises energy reserves for vigorous physical activity or regular training. As the length of the exercise continues, the source of the carbohydrate may shift from the muscle glycogen pool to circulating blood glucose, but if the blood glucose cannot be maintained, the intensity of the exercise will decrease [58]. Additionally, carbohydrate plays an important role as a protein sparer during exercise. Carbohydrate availability inhibits protein catabolism in exercise [59], although studies have documented that females have a greater capacity for lipid oxidation during exercise. This fact allows them to maintain normoglycemia (the presence of a normal concentration of glucose in the blood) and preserve muscle glucose during long sport events. If an athlete consumes 60–65 % of their calories from carbohydrate and energy balance is being maintained, sufficient muscle glycogen stores should be maintained from day to day. The athlete also has a lower amino acid breakdown during exercise if carbohydrate intake is 60–65 % of their total caloric intake [60].

Nutritional strategies are needed for optimal recovery of fuel deposits following exercise. Studies have demonstrated improved glycogen repletion when carbohydrates were consumed immediately after exercise instead of some hours later [60]. Carbohydrate-rich meals are recommended during recovery, preferably of a high glycemic index. Adding 0.2–0.5 g of protein per day per kg of body mass to carbohydrates in a 3:1 (carbohydrate:protein) ratio is recommended [60]. Appropriate recovery foods with a favorable mix of carbohydrate and protein include yogurt with granola; crackers, cheese, and fruit; a small smoothie; a bagel with soy nut, almond, or peanut butter; and jam or honey [61]. No difference has been observed in terms of glycogen repletion whether the sources of carbohydrates are solid or liquid [60].

Protein requirements are slightly increased in highly active people. Protein requirements for endurance athletes are 1.2–1.4 g/kg body mass per day whereas those for resistance-trained and strength-trained athletes may be as high as 1.6–1.7 g/kg of body mass per day. Acceptable levels for protein intake for physically active persons may range from 10 to 35 % of calorie [40]. Foods containing proteins with a high biological availability (a high retention and utilization rate by the body) should be emphasized. Research suggests that consuming 20 g of protein 5–6 times per day may be preferable to larger protein intake less frequently [62]. Meats, fish, eggs, and dairy products offer complete sources of protein (providing all essential amino acids) [6063].

Fat intake should not be restricted provided that the fat intake is low in saturated fats and trans fats; there is no benefit in consuming a diet with less than 15 % of energy from fat as compared with 20–25 % [39]. To maintain body mass the majority of athletes need an energy intake around 40–50 kcal/kg/day which in practical terms is very hard to obtain solely by increasing carbohydrate consumption; some authors remark that such a large shift is likely to lead to a deficit in some essential proteins and lipids and compromise nitrogen balance necessary to maintain normal sexual steroid hormone levels. So for athletes, the acceptable range of fat intake is from 10 to 35 % of caloric intake [39].

Micronutrients play an important role in energy production, hemoglobin synthesis, maintenance of bone health, adequate immune function, and protection of body against oxidative damage. Routine exercise may also increase the turnover and loss of these micronutrients from the body. As a result, greater intakes of micronutrients may be required to cover increased needs for building, repair, and maintenance of lean body mass in athletes [61].

Vitamins B1, B2, B3, and B6, pantothenic acid, and biotin are crucial in energy metabolism, and many athletes have a diet low in those vitamins although few research has been made about the consequences of vitamin B-deficient diets in athletes either for their health or for sport performance. Low intakes of folic acid or vitamin B12 can lead to anemia [40]. Furthermore, some recent research points out that an increasing evidence exists for a possible fourth component of the triad, endothelial dysfunction, and this finding is a cause for concern because the sentinel event in cardiovascular disease pathogenesis is impaired endothelial function [6467].

It has been documented that folic acid supplementation can improve endothelium-dependent vasodilation, and some researchers showed that supplementation with 10 mg/day of folic acid for 4–6 weeks significantly improved flow-mediated dilation in eumenorrheic and amenorrheic athletes [6870]. More research is needed to define the optimal dosage and length of treatment with folic acid in athletes with endothelial dysfunction.

Exercise increases oxygen consumption by 10–15-fold, thus increasing oxidative stress. Even though short-term exercise may increase the levels of lipid peroxide by-products, habitual exercise has been shown to result in an augmented antioxidant system and reduced lipid peroxidation [487172]. Thus, a well-trained athlete may have a more developed endogenous antioxidant system than a sedentary person. Whether exercise increases the need for antioxidant nutrients remains controversial. There is little evidence that antioxidant supplements enhance physical performance. Nevertheless a suboptimal dietary intake of antioxidants as vitamin E, vitamin C, or selenium may lead to health problems [7375].

Vitamin D status is another important factor in preserving bone health. Athletes who live at northern latitudes or who train primarily indoors throughout the year, such as gymnasts and figure skaters, are at risk for poor vitamin D status, especially if they do not consume foods fortified with vitamin D [4060]. Supplementation with calcium and vitamin D should be determined after nutrition assessment. Current recommendations for athletes with disordered eating, amenorrhea, and risk for early osteoporosis are 1,500 mg of elemental calcium and 400–800 IU of vitamin D per day [21].

Iron is required for the formation of oxygen-carrying proteins, hemoglobin and myoglobin, and for enzymes involved in energy production. Iron depletion (low iron stores) is one of the most prevalent nutrient deficiencies observed among female athletes [76]. Iron deficiency, with or without anemia, can impair muscle function and limit work capacity. Low-energy diets or vegetarian diets, with poor availability sources of iron, are common causes of iron-deficit anemia. Nutritional assessment and counseling should be done before anemia appears and supplements recommended if needed. Table 29.7summarizes key points regarding nutritional recommendations for the physically active person.

Table 29.7

Summary of recommendations for macronutrients and energy intake for the physically active female

The food guide pyramid provides broad recommendations for healthful nutrition for the physically active individual. Diets should be rich in nutrient-dense foods and emphasize fruits and vegetables, cereals and whole grains, nonfat and low-fat dairy products, legumes, nuts, fish, poultry, and lean meats. Female athlete’s diets have been found to be low on iron, calcium, zinc, vitamin B6, and folate. They should make sure that their diet contains foods that contain these vitamins and minerals.

Intensity of daily physical activity largely determines energy intake requirements.

Studies consistently show that female athletes are not consuming enough energy to support their activity levels. Energy intakes of well-trained female athletes range from 1,931 to 3,573 kcal. However, during high-volume training, such as in swimming, total daily energy may increase to 5,593 kcal daily. Low energy and nutrient intake places athletes at greater risk for nutrition-related disorders such as amenorrhea, osteoporosis, iron-deficiency anemia, and eating disorders. A minimum of 30–40 kcal/kg/day are needed to avoid functional amenorrhea.

Precise recommendations do not exist for daily lipid and carbohydrate intake.

Fat intake should not be restricted provided that the fat intake is low in saturated fats and trans fats; there is no benefit in consuming a diet with less than 15 % of energy from fat as compared to 20–25 %. An acceptable lipid intake for physically active individuals ranges from 10 to 35 % of caloric intake.

Carbohydrate intake is important for the physically active person. General recommendations for carbohydrates range between 6 and 10 g/kg of body mass per day. This range represents approximately 55–65 % carbohydrate intake. Carbohydrates should be predominantly starches from fiber-rich, unprocessed grains, fruits, and vegetables. A low-carbohydrate diet rapidly compromises energy reserves for vigorous physical activity or regular training. Successive days of hard training gradually deplete carbohydrate reserves, even when maintaining the recommended carbohydrate intake. This could lead to “staleness,” making continued training more difficult.

Studies have demonstrated improved glycogen repletion when carbohydrates were consumed immediately after exercise instead of some hours later. Carbohydrate-rich meals are recommended during recovery, preferably meals with a high glycemic index. Adding 0.2–0.5 g of protein per day per kg of body mass to carbohydrates in a 3:1 (carbohydrate:protein) ratio is recommended.

Protein requirements are slightly increased in highly active people. Protein requirements for endurance athletes are 1.2–1.4 g/kg body mass per day whereas those for resistance- and strength-trained athletes may be as high as 1.6–1.7 g/kg of body weight per day. According to the Dietary Reference Intakes, acceptable macronutrient distribution ranges of protein for adults are 10–35 %.

Excessive sweating during exercise causes loss of body water and related minerals. Mineral loss should be replaced following exercise through well-balanced meals. Athletes should be well hydrated before beginning to exercise. During exercise, optimal hydration can be facilitated by drinking 150–350 mL (6–12 oz) of fluid at 15–20-min intervals, beginning at the start of the exercise. Consuming up to 150 % of the weight lost during an exercise session may be necessary to cover losses in sweat and urine excretion. Enhancing palatability of the ingested fluid is one way to help promote fluid consumption, before, during, or after exercise. Fluid palatability is influenced by several factors including temperature, sodium content, and flavoring. The preferred water temperature is often between 15 and 21 °C, but this and flavor preference vary greatly between individuals and cultures.

29.4.2 The Importance of Hydration Before, During, and After Exercise

Water balance is essential for a good health. As we do not have a real “water body store” we need to replace water losses on a day-to-day basis. Exercise increments body temperature and can elicit high sweat rates and water and electrolyte losses particularly in warm-hot weather.

There is considerable variability for water and electrolyte losses between individuals and between different activities, and if sweat water and electrolyte losses are not replaced, then the person will dehydrate. Dehydration can impair exercise performance, contribute to serious health problems as heat illness, and exacerbate symptomatic rhabdomyolysis [7778]. An excess of water intake is also possible but less common. Excessive water intake leads to hyponatremia with sever health consequences [77].

Athletes should be well hydrated before beginning to exercise. In addition to drinking generous amounts of fluid in the 24 h before an exercise session, 4-h pre-exercise, they should consume 5–7 mL/kg body weight. Consuming beverages with sodium (20–50 mEqI/L) and/or small amounts of salted snacks or sodium-containing foods at meals will help to stimulate thirst and retain the consumed fluids [77]. During exercise, individuals should periodically drink depending on environmental conditions, exercise intensity and duration, and opportunities to drink. Optimal hydration can be facilitated by drinking 150–350 mL (6–12 oz) of fluid at 15- to 20-min intervals, beginning at the start of the exercise [7980]. In most cases, athletes do not consume enough fluids during exercise to balance fluid losses and thus complete their exercise sessions dehydrated to some extent. Consuming up to 150 % of the weight lost during an exercise session may be necessary to cover losses in sweat and urine excretion [81].

Following exercise, the goal is to fully replace any fluid and electrolyte deficit. The general guidelines are to consume 20 oz of fluid (only fluid or fluid plus foods with a high % of water) for every pound lost during exercise [61]. If recovery time is sufficient, consumption of normal meals and snacks with a sufficient volume of plain water will be enough, provided the food contains sufficient sodium to replace sweat losses. When more rapid rehydration is warranted, a sports beverage is preferred because it provides fluid, carbohydrates, and electrolytes.

The composition of the consumed fluids can be important. The IOM provided general guidance for composition of “sports beverages” for persons performing prolonged physical activity in hot weather. They recommend that these types of fluid replacement beverages might contain approximately 20–30 meq/L sodium (chloride as the anion), 2–5 meq/L potassium, and 5–10 % carbohydrate. These components also can be consumed by nonfluid sources such as gels, energy bars, and other foods [82].

29.5 Concluding Remarks

For female athletes, energy balance must be maintained for optimum health and athletic performance. The minimum amount of calories a female should consume to prevent functional amenorrhea is 30 kcal/kg/LBM. A caloric intake less than this affects many of the hormones involved in glucose availability, metabolism, and reproduction. Historically, female athletes, competing in sports where leanness increases performance, have not taken in enough calories to meet their energy needs. A joint position statement by the American College of Sports Medicine, the American Dietetic Association, and the Dietitians of Canada states that a diet substantially different from that recommended in the Dietary Guidelines for Americans or the Nutrition Recommendations for Canadians is not needed for athletes [3941]. It is recommended that an athlete’s diet should consist of nutrient-dense food and beverages within and among the basic good groups while choosing foods that limit the intake of saturated and trans fats, cholesterol, added sugars, salt, and alcohol. Athletes should also be well hydrated before beginning to exercise and should drink enough fluid during and after exercise to balance fluid losses.

Appendix 1: Dietary Reference Intakes

The FNIC is a leader in online global nutrition information. Located at the NAL of USDA, the FNIC website contains over 2,500 links to current and reliable nutrition information.

FNIC provides links to the DRI tables, developed by the IOM’s Food and Nutrition Board. To view these tables or download these tables in a PDF file, please go to http://​fnic.​nal.​usda.​gov/​dietary-guidance/​dietary-reference-intakes/​dri-tables

Dietary Reference Intakes: Recommended Intakes for Individuals

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

Comprehensive DRI tables for vitamins, minerals, and macronutrients; organized by age and gender. Includes the 2010 updated recommendations for calcium and vitamin D.

Dietary Reference Intakes: RDA and AI for Vitamins and Elements (PDF | 28 Kb)

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

DRI tables for recommended dietary allowances (RDA) and adequate intakes (AI) of vitamins and elements, including the 2010 updated recommendations for calcium and vitamin D.

Dietary Reference Intakes: UL for Vitamins and Elements (PDF | 19 Kb)

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

DRI table for tolerable upper intake levels (UL) of vitamins and elements, including the 2010 updated recommendations for calcium and vitamin D.

Dietary Reference Intakes: Macronutrients

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

DRI table for carbohydrate, fiber, fat, fatty acids, and protein.

Dietary Reference Intakes: Estimated Average Requirements (PDF | 15 Kb)

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

DRI table for nutrients that have an estimated average requirement (EAR), the average daily nutrient intake level estimated to meet the requirements of half of the healthy individuals in a group.

Dietary Reference Intakes: Electrolytes and Water

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

DRI table for sodium, chloride, potassium, inorganic sulfate, and water.

Note: You can access these tables at http://​fnic.​nal.​usda.​gov/​dietary-guidance/​dietary-reference-intakes/​dri-tables

Appendix 2: Dietary Reports

The FNIC is a leader in online global nutrition information. Located at the NAL of USDA, the FNIC website contains over 2,500 links to current and reliable nutrition information.

FNIC provides links and PDF downloads to the DRI reports, developed by the IOM’s Food and Nutrition Board. To distribute or reprint these reports, please visit The National Academies Press website to secure all necessary permissions.

http://​fnic.​nal.​usda.​gov/​dietary-guidance/​dietary-reference-intakes/​dri-reports

UPDATEDDietary Reference Intakes for Calcium and Vitamin D (2010) (PDF | 355 Kb)

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

Report briefly on new DRIs for calcium and vitamin D, revised in November 2010. Read the prepublication report at the National Academies Press website.

Dietary Reference Intakes: The Essential Guide to Nutrient Requirements

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

All eight volumes of the DRIs are summarized in one reference volume, organized by nutrient, which reviews function in the body, food sources, usual dietary intakes, and effects of deficiencies and excessive intakes.

Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride (1997)

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

For the 2010 updated recommendations for calcium and vitamin D, refer to the prepublication report at the National Academies Press website.

Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients) (2005)

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (1998)

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc (2001)

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

Dietary Reference Intakes: Proposed Definition of Dietary Fiber (2001)

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids (2000)

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate (2004)

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

Dietary Reference Intakes: Guiding Principles for Nutrition Labeling and Fortification (2003)

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

Dietary Reference Intakes: Applications in Dietary Planning (2003)

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

Dietary Reference Intakes: Applications in Dietary Assessment (2000)

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

Dietary Reference Intakes Research Synthesis Workshop Summary (2006)

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

Dietary Reference Intakes: Proposed Definition and Plan for Review of Dietary Antioxidants and Related Compounds (1998)

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

Dietary Reference Intakes: A Risk Assessment Model for Establishing Upper Intake Levels for Nutrients (1998)

National Academy of Sciences. Institute of Medicine. Food and Nutrition Board.

Appendix 3. Dietary Assessment Tool Found at the National Agricultural Library (http://​fnic.​nal.​usda.​gov/​dietary-guidance/​dietary-assessment)

Find the SuperTracker and other tools related to dietary assessment, including calorie calculators and the National Cancer Institute’s Diet History Questionnaire. Also find a link to the Dietary Assessment Calibration/Validation Register, a registry of validation studies and publications.

USDA. 0043enter for Nutrition Policy and Promotion.

This practical tool lets you plan, analyze, and track your eating and activity habits. Gives tips for making healthy changes.

Nutrition Analysis Tool (NAT)

University of Illinois. Department of Food Science and Human Nutrition.

A free Web-based nutrient analysis program. Requires log-in.

Activity Calorie Calculator

Fitness Jumpsite.

Calculates the number of calories burned for a variety of physical activities.

Fat Intake Screener

NutritionQuest.

Compares individual fat intake to that of the average American.

Fruit, Vegetable and Fiber Screener

NutritionQuest.

Do you get your five-a-day? Find out if you're eating enough fruits and vegetables to reduce the risk of chronic disease.

Healthy Body Calculator

Ask the Dietitian.

Calculator provides results on weight, body frame size, body mass index (BMI), waist-to-hip ratio, nutrient recommendations, and physical activity.

Diet History Questionnaire

DHHS.NIH. National Cancer Institute.

Part of Risk Factor Monitoring and Methods, this questionnaire provides background information and tools and resources for utilizing this program.

Dietary Assessment Calibration/Validation Register

DHHS. NIH. National Cancer Institute.

Register contains studies and publications which compare dietary intake estimates from two or more dietary assessment methods.

Behavior Change and Maintenance

DHHS. NIH. Office of Behavioral and Social Sciences Research.

Summary report of research on key health behaviors and lifestyle factors affecting disease.

USDA Healthy Eating Index

USDA. Center for Nutrition Policy and Promotion.

The HEI is a summary measure of overall diet quality.

Appendix 4: Estimated Calorie Requirements (in Kilocalories) for Specific Age Groups at Three Levels of Physical Activitya Using the Institute of Medicine Equations

   

Activity levelb,c,d

   

Gender

Age (years)

Sedentaryb

Moderately activec

Actived

Child

2–3

1,000

1,000–1,400e

1,000–1,400e

Female

4–8

1,200

1,400–1,600

1,400–1,800

9–13

1,600

1,600–2,000

1,800–2,000

14–18

1,800

2,200

2,400

19–30

2,000

2,000–2,200

2,400

31–50

1,800

2,000

2,200

51+

1,600

1,800

2,000–2,200

Male

4–8

1,400

1,400–1,600

1,600–2,000

9–13

1,800

1,800–2,200

2,000–2,600

14–18

2,200

2,400–2,800

2,800–3,200

19–30

2,400

2,600–2,800

3,000

31–50

2,200

2,200–2,600

2,800–3,000

51+

2,000

2,200–2,400

2,400–2,800

aThese levels are based on estimated energy requirements (EER) from the Institute of Medicine Dietary Reference Intakes macronutrients report, 2002, calculated by gender, age, and activity level for reference-sized individuals. “Reference size,” as determined by IOM, is based on median height and weight for ages up to 18 years and median height and weight for that height to give a BMI of 21.5 for adult females and 22.5 for adult males. The estimates are rounded to the nearest 200 calories

bSedentary means a lifestyle that includes only the light physical activity associated with typical day-to-day life

cModerately active means a lifestyle that includes physical activity equivalent to walking about 1.5 to 3 miles per day at 3 to 4 miles per hour, in addition to the light physical activity associated with typical day-to-day life

dActive means a lifestyle that includes physical activity equivalent to walking more than 3 miles per day at 3 to 4 miles per hour, in addition to the light physical activity associated with typical day-to-day life

eThe calorie ranges shown are to accommodate the needs of different ages within the group. For children and adolescents, more calories are needed at older ages. For adults, fewer calories are needed at older ages

Appendix 5: Nutrition Questionnaire with 3-Day Recall

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2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

Appendix 6: Food Frequency Questionnaire

The following questionnaire is designed to help the dietician determine the frequency of food use. It should be used in conjunction with a 3-day recall of food intake. Record as accurately as possible. Amounts should be recorded in measurable amounts (e.g., cups, pounds, teaspoons), and frequencies should be recorded in measurable amounts of time (e.g., 1 day, 3 months, 2 weeks).

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2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

Adapted from Dynamics of Nutrition Support: Assessment, Evaluation, and Implementation. Krey, S.H.,& Murray, R.L., Appleton-Century-Crofts, 1986.

Appendix 7: Eating Disorder Organizations and Resources

Anorexia Nervosa and Related Eating Disorders, Inc. (ANRED)

Internet: http://​www.​anred.​com/​

ANRED’s mission is to provide easily accessible information on anorexia nervosa, bulimia nervosa, binge-eating, and other food and weight disorders. ANDRED, a nonprofit organization, distributes materials on topics such as

Soy Unica! Soy Latina!

Internet: http://​www.​soyunica.​org/​mybody/​default.​htm

An excellent bilingual website for young Latinas with a good section on eating disorders.

Eating Disorder Information and Referral Center

Internet: www.​EDreferral.​com

This website is a resource for information and treatment options for all forms of eating disorders. It includes referrals to local treatment centers nationwide.

Harvard Eating Disorders Center (HEDC)

WACC 725

15 Parkman Street

Boston, MA 02114

Tel: (617) 236-7766

E-mail: info@hedc.org

Internet: http://​www.​hedc.​org/​

The Harvard Eating Disorders Center is a national nonprofit organization dedicated to research and education and gaining new knowledge of eating disorders, their detection, treatment, and prevention to share with the community at large. The website includes information about eating disorders, help for family and friends, resources and a listing of events and programs.

Overeaters Anonymous (OA)

World Service Office

PO Box 44020

Rio Rancho, NM 87174-4020

Tel: (505) 891-2664

E-mail: info@overeatersanonymous.org

Internet: http://​www.​overeatersanonym​ous.​org/​

OA is a nonprofit international organization that provides volunteer support groups worldwide. Modeled after the 12-step Alcoholics Anonymous program, the OA recovery program addresses physical, emotional, and spiritual recovery aspects of compulsive overeating. Members are encouraged to seek professional help for individual diet and nutrition plans and for any emotional or physical problems.

The Renfrew Center Foundation

475 Spring Lane

Philadelphia, PA 19128

Tel: 1-800-RENFREW

E-mail: foundation@renfrew.org

Internet: http://​www.​renfrew.​org/​

The Renfrew Center Foundation is a tax-exempt, nonprofit organization promoting the education, prevention, treatment, and research of eating disorders. The Renfrew Center Foundation is funded by private donations and by the Renfrew Center, the nation’s first freestanding facility committed to the treatment of eating disorders.

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