The Overweight Athlete
Chapter 35 The Overweight Athlete MELINDA M. MANORE Introduction For the sport medicine team, the overweight athlete can present numerous challenges. First, the type of athlete who wants or needs to lose weight can vary dramatically, from a small female participating in a lean build sport (gymnastics, track and ﬁeld, ﬁgure skating) to a large male participating in a strength or power sport (weightlifting, heavy weight wrestling). Some of these athletes may also participate in sports that require ‘making weight,’ which adds a unique challenge to any health professional guiding them through the weight-loss process. These athletes may not be ‘overfat or overweight’ according to normal criteria, but may be considered heavy for their sport or for the weight category in which they must compete. To further complicate the weight-loss process, some athletes participate in sports in which they are judged on both performance and appearance. This can add pressure to reduce body weight lower than optimal for good health and performance. Second, the weight-loss programme needs to provide adequate energy so that exercise training can still occur. The diet cannot be too restrictive in energy without the athlete running the risk of injury, loss of fat-free mass (FFM), poor performance, feelings of deprivation, and eventual failure. Thus, adequate time needs to be allotted for weight loss to occur. Aerobic and strength training may also need to be added if they are not already a part of the athlete’s normal training programme. Finally, the weight-loss programme needs to provide a strong educational component. The athlete needs to be taught good nutritional, exercise and behavioural techniques for long-term weight maintenance. Without an educational component, the athlete is susceptible to the many fad diets, diet products, and weight-loss drugs that frequently hit the consumer market. With the emphasis placed on physical appearance in Western society, dieting can become obsessive. The athlete is not immune to this pressure. In fact, they are pressured on two fronts: their sport and society. This pressure can lead to desperate means of weight loss and an eventual eating disorder. This review will brieﬂy outline the principles and components of energy balance that need to be considered before placing an athlete on a weight-loss programme. Speciﬁc methods for determining energy balance in an athlete will also be reviewed. Finally, practical applications and guidelines for determining the weight-loss goal and approaches to gradual weight loss will be given. For individuals working with athletes in weight-category sports, the effects of rapid weight loss on health and performance has been addressed elsewhere (Steen & Brownell 1990; Horswill 1992, 1993; Fogelholm 1994). Other excellent reviews are available on the effect of weight loss on sport performance (Wilmore 1992a), the techniques used in different sports (Fogelholm 1994; Burke 1995), the effect of weight loss on health and metabolism (Brownell et al. 1987), and the role of dieting in eating disorders (Wilmore 1991; Sundgot-Borgen 1993, 1994; 469 470 practical issues Beals & Manore 1994) and menstrual dysfunction (Dueck et al. 1996). Part 4 of this book gives more speciﬁc information about the weight and nutrition concerns of different sports, particularly weight-category sports. Energy and nutrient balance The classic energy balance equation states that if energy intake equals energy expenditure then weight is maintained; however, this equation does not allow for changes in body composition and energy stores (Ravussin & Swinburn 1993). The maintenance of body weight and composition over time requires that energy intake equals energy expenditure, and that dietary intakes of protein, carbohydrate, fat and alcohol equal their oxidation rates (Flatt 1992; Swinburn & Ravussin 1993). If this occurs, an individual is considered to be in energy balance and body weight and composition will be maintained. This approach to energy balance is dynamic and allows for the effect of changing energy stores on energy expenditure over time. For example, after a short period of positive energy balance, the extra energy would cause weight gain (of both fat and lean tissues). However, the larger body size would cause an increase in energy expenditure that would eventually balance the extra energy consumed. Thus, weight gain can be the consequence of an initial positive energy balance, but can also be a mechanism whereby energy balance is eventually restored. Conversely, weight loss must reverse this process. If body fat is to be lost, energy intake must be less than expenditure, and fat oxidation must exceed fat intake (Westerterp 1993). Nutrient balance The alteration of energy intake and expenditure is just one part of the energy balance picture. Changes in the type and amount of nutrients consumed (i.e. protein, fat, carbohydrate and alcohol) and the oxidation of these nutrients within the body must also be considered. Under normal physiological conditions, carbohydrate, protein and alcohol are not easily converted to body fat (Abbott et al. 1988; Swinburn & Ravussin 1993). Thus, increases in the intake of non-fat nutrients stimulate their oxidation rates proportionally. Conversely, an increase in fat intake does not immediately stimulate fat oxidation, hence increasing the probability that dietary fat will be stored as adipose tissue (Abbott et al. 1988; Westerterp 1993). Therefore, the type of food consumed plays a role in the amount of energy consumed and expended each day (Acheson et al. 1984; Swinburn & Ravussin 1993). Successful weight loss requires that an energy deﬁcit be produced (either through increased energy expenditure and/or decreased energy intake) and diet composition and oxidation be altered (decreased fat intake and/or increased fat oxidation through exercise) (Hill et al. 1993). Carbohydrate balance Carbohydrate balance is proposed to be precisely regulated (Flatt 1992), with the ingestion of carbohydrate stimulating both glycogen storage and glucose oxidation, and inhibiting fat oxidation (Fig. 35.1). Glucose not stored as glycogen is thought to be oxidized directly in almost equal balance to that consumed (Schutz et al. 1989; Thomas et al. 1992). Thus, the conversion of excess dietary carbohydrate to triglycerides does not appear to occur to any large extent in humans under normal physiological conditions (Acheson et al. 1988; Hellerstein et al. 1991). Protein balance Like carbohydrate, the body alters protein oxidation rates to match protein intakes (Thomas et al. 1992). Once anabolic needs are met, the carbon skeletons of excess amino acids can be used for energy. The adequacy of both energy and carbohydrate intake dramatically affects this process. Inadequate energy or carbohydrate intakes will result in negative protein balance, while excess intake of energy or carbohydrate will spare protein (Krempf et al. 1993). Any excess dietary protein or that made available through protein the overweight athlete Protein oxidation (g.day–1) 150 100 50 0 0 50 100 150 100 50 (a) 1000 500 800 400 600 400 200 0 0 (b) 400 600 800 CHO intake (g.day–1) 200 200 100 0 (b) 100 200 300 400 CHO intake (g.day–1) 500 300 Fat oxidation (g.day–1) 100 50 0 (c) 100 150 Protein intake (g.day–1) 300 1000 150 –50 0 50 0 200 200 Fat oxidation (g.day–1) 150 0 0 200 Protein intake (g.day–1) (a) CHO oxidation (g.day–1) 200 CHO oxidation (g.day–1) Protein oxidation (g.day–1) 200 471 50 100 Fat intake 150 100 0 0 200 (g.day–1) 200 (c) 100 200 300 Fat intake (g.day–1) Fig. 35.1 High-carbohydrate diet: the relationship between intake and oxidation of (a) protein, (b) carbohydrate (CHO), and (c) fat for all subjects on day 7 of a high carbohydrate feeding period. — , regression line for all 21 subjects; - - - , regression line for lean subjects (䊊); · · · ·, regression line for obese subjects (䊉). (a) Lean subjects: r = 0.79, P < 0.01; obese subjects: r = 0.59, n.s. (b) Lean subjects: r = 0.74, P < 0.01; obese subjects: r = 0.79, P < 0.01. (c) Lean subjects: r = 0.06, n.s.; obese subjects: r = –0.08, n.s. From Thomas et al. (1992), with permission. Fig. 35.2 High-fat diet: the relationship between intake and oxidation of (a) protein, (b) carbohydrate (CHO), and (c) fat for all subjects on day 7 of a high fat feeding period. — , regression line for all 21 subjects; - - - , regression line for lean subjects (䊊); · · · ·, regression line for obese subjects (䊉). (a) Lean subjects: r = 0.78, P < 0.01; obese subjects: r = 0.74, P < 0.02. (b) Lean subjects: r = 0.32, n.s.; obese subjects: r = 0.14, n.s. (c) Lean subjects: r = 0.78, P < 0.01; obese subjects: r = 0.02, n.s. From Thomas et al. (1992), with permission. sparing may contribute indirectly to fat storage by sparing dietary fat. Figure 35.2 shows that as fat intake increases, the oxidation of fat does not increase proportionately (Thomas et al. 1992). Thus, acute increases in fat intake have little inﬂuence on fat oxidation. For example, Jebb et al. (1996) overfed three lean men by 33% of energy requirements for 12 days. They found that carbohydrate and protein intake Fat balance Fat balance is not as precisely regulated as either protein or carbohydrate balance (Flatt 1992). 472 practical issues (grams per day) matched their oxidation rates, while fat oxidation rates did not change signiﬁcantly even though fat intake increased (fat intake was 150 g · day–1 while fat oxidation was only 59 g · day–1). The result was a 2.9-kg weight gain in 12 days. Thus, excess energy eaten as dietary fat is stored as triglycerides in adipose tissue with little loss of energy (Acheson et al. 1984; Swinburn & Ravussin 1993). Alcohol balance When athletes ingest alcohol, it becomes a priority fuel, with a rapid rise in alcohol oxidation occurring until all the alcohol is cleared from the body. Alcohol also suppresses the oxidation of fat and, to a lesser degree, that of protein and carbohydrate (Shelmet et al. 1988). Alcohol is not stored as fat nor can it contribute to the formation of muscle or liver glycogen. It may, however, indirectly divert fat to storage by providing an alternative and preferred energy source for the body (Sonko et al. 1994). Thus, alcohol, at 29.4 kJ · g–1 (7 kcal · g–1), can contribute signiﬁcantly to total energy intake. Athletes who consume alcohol must reduce their intake of energy from other sources to maintain energy balance. Energy balance Determination of energy balance requires the measurement or estimation of both energy intake and energy expenditure. Energy balance is then estimated by subtracting energy expenditure from energy intake. This section will brieﬂy review the various components of energy intake and expenditure, how these components are measured, and the many factors that may inﬂuence them. Components of energy expenditure The components of total daily energy expenditure (TDEE) are generally divided into three main categories: (i) resting metabolic rate (RMR), (ii) the thermic effect of food (TEF), and (iii) the thermic effect of activity (TEA) (Fig. 35.3). RMR is the energy required to maintain the systems of the body and to regulate body temperature at rest. In most sedentary healthy adults, RMR accounts for approximately 60–80% of TDEE (Bogardus et al. 1986; Ravussin et al. 1986). However, in an active individual this percentage can vary greatly. It is not unusual for some athletes to expend 4.2–8.4 MJ (1000–2000 kcal) per day in sport-related activities. For example, Thompson et al. (1993) determined energy balance in 24 elite male endurance athletes over a 3–7-day period and found that RMR represented only 38–47% of TDEE. Similar results are reported in female runners (Beidleman et al. 1995). The TEF is the increase in energy expenditure above RMR that results from the consumption of food throughout the day. It includes the energy cost of food digestion, absorption, transport, metabolism and storage within the body, and the energy expended due to sympathetic nervous system activity brought about by seeing, smelling and eating food. TEF is usually expressed as a percentage of the energy content of the foods consumed and accounts for 6–10% of TDEE, with women usually having a lower value (approximately 6–7%) (Poehlman 1989). However, this value will vary depending on the energy density and size of the meal and types of foods consumed. In addition, if the absolute amount of energy intake is decreased, then it follows that the absolute amount of energy expended in TEF will decrease. TEA is the most variable component of energy expenditure in humans. It includes the energy cost of daily activities above RMR and TEF, such as purposeful activities of daily living (making dinner, dressing, cleaning house) and planned exercise (running, weight training, cycling). It also includes the energy cost of involuntary muscular activity such as shivering and ﬁdgeting. This type of movement is called spontaneous physical activity. TEA may be only 10–15% of TDEE in sedentary individuals, but may be as high as 50% in active individuals. The addition of RMR, TEF and TEA should account for 100% of the overweight athlete 100 Determinants – Intensity Unrestricted activity – Duration Arousal – Fat-free device – Fat mass – Age 25 SMR BMR – Sex Respiratory chamber – Amount/composition of food (hormones/SNS) Thermic effect of food Ventilated hood % of daily energy expenditure – Genetics/SNS? SPA Doubly labelled water – Body weight 75 50 473 – Genetics – Hormones/SNS 0 Methods Fig. 35.3 Components of daily energy expenditure in humans. Daily energy expenditure can be divided into three major components: (i) the basal metabolic rate (BMR) (the sum of the sleeping metabolic rate (SMR) and the energy cost of arousal), which represents 50–70% of daily energy expenditure; (ii) the thermic effect of food, which represents approximately 10% of daily energy expenditure; and (iii) the energy cost of physical activity (the sum of spontaneous physical activity (SPA) and unrestricted/voluntary physical activity), which represents 20–40% of daily energy expenditure. The major determinants of the different components of daily energy expenditure, as well as the methods to measure them, are presented. SNS, sympathetic nervous system. From Ravussin and Swinburn (1993). TDEE. However, there are a variety of factors that may increase energy expenditure above normal, such as cold, fear, stress, and various medications or drugs. These factors are referred to as adaptive thermogenesis and represent a temporary increase in thermogenesis that may last for hours or days, depending on the duration and magnitude of the stimulus. For example, a serious injury, the stress associated with competition, going to high altitudes, or the use of certain drugs may all increase RMR. Factors that inﬂuence RMR It is well documented that RMR is inﬂuenced by gender, age and body size, including the amount of FFM and fat mass. These four variables generally explain about 80% of the variability in RMR (Bogardus et al. 1986). Since FFM has a high rate of metabolic activity, any change in FFM would dramatically inﬂuence RMR. In general, males have higher RMRs than females because they usually weigh more and have more FFM. However, Ferraro et al. (1992) found that females have a lower RMR than males (approximately 100 kcal less per day) even after differences in FFM, fat mass and age are controlled. Age is another variable known to inﬂuence RMR. It is estimated that the decline in RMR is less than 1–2% per decade from the second to the seventh decade of life (Keys et al. 1983). It is now known that RMR also has a genetic component. This means that within a family members may have similar RMRs. Two studies illustrate this phenomenon. Bogardus et al. (1986) found that family membership could explain 474 practical issues 11% of the variability in RMR (P < 0.0001) in American Indians from 54 families. Similarly, Bouchard et al. (1989) found that in twins and parent–child pairs, heritability explained approximately 40% of the variability in RMR after adjusting for age, gender and FFM. Research now indicates that RMR may ﬂuctuate over the phases of the menstrual cycle, with RMR values lowest during the follicular phase and highest during the luteal phase (Solomon et al. 1982; Bisdee et al. 1989). The difference in RMR between these two phases is approximately 420–1260 kJ · day–1 (100–300 kcal · day–1). It also appears that adaptations in energy intake mimic the changes in RMR. Barr et al. (1995) found that females consume approximately 1260 kJ · day–1 (300 kcal · day–1) more during the luteal phase of the menstrual cycle than during the follicular phase. Thus, the increased energy expenditure, due to a higher RMR during the luteal phase, is compensated by an increase in energy intake during this period. However, if an athlete is amenorrhoeic, these changes in RMR will not occur. Data are not available for anovulatory females who may be menstruating but have depressed hormonal proﬁles. Although there is substantial research to suggest that RMR changes over the menstrual cycle, not all research is supportive of these ﬁndings. Weststrate (1993) showed no effect of menstrual cycle on RMR, and Piers et al. (1995) showed no effect of menstrual cycle phase on RMR or energy intake. effect of exercise on rmr For the athlete participating in an intense training programme, exercise may affect RMR both directly and indirectly. First, exercise can directly increase RMR if it increases FFM (Bogardus et al. 1986). Second, intense exercise training can temporarily increase resting energy expenditure above the typical RMR long after the exercise bout has ended. This short-term increase in energy expenditure is termed excess postexercise oxygen consumption (EPOC) and is the amount of energy expended above the typical RMR. The extent of EPOC after an exercise bout and the effect it has on TDEE appears to depend on the exercise intensity and/or the duration (Bahr 1992). For example, Bahr et al. (1987) found that . aerobic exercise (70% Vo2max.) lasting 80 min produced a 15% increase in EPOC lasting for 12 h after exercise. Similarly, 2 min of exercise at 108% . Vo2max., repeated three times, produced a signiﬁcant increase in EPOC for 4 h after exercise (Bahr et al. 1992). Although most research has examined the effect of aerobic exercise on EPOC, Melby et al. (1993) found a signiﬁcant increase in EPOC after 90 min of weightlifting. Oxygen consumption was elevated by 5–10% over baseline the following morning. Finally, it appears that energy ﬂux can also alter RMR. Energy ﬂux is deﬁned as the amount of energy expended in exercise compared with the amount of energy consumed each day. An athlete who is exercising intensely and eating adequate energy would be in high energy ﬂux, while an athlete who is exercising intensely, but restricting energy intake would be in negative energy ﬂux. Bullough et al. (1995) examined the effect of energy ﬂux on RMR in trained male athletes. They measured RMR after 3 days of high-intensity exercise (90 min of cycling at 75% . Vo2max., while eating adequate energy) and after 3 days of exercise when energy intake was reduced (energy intake matching that required on a no-exercise day). They found that RMR was signiﬁcantly higher during high energy than during negative energy ﬂux. Thus, two athletes may be doing similar workouts, but have dramatically different energy expenditures if one is restricting energy intake and the other is not. Factors that inﬂuence TEF A number of factors can inﬂuence how athletes’ bodies respond metabolically to the food they consume. Some of these factors are associated with the physiological characteristics of an individual such as genetic background, age, level of physical ﬁtness, sensitivity to insulin, or level of body fat. Other factors are associated with the meal, such as meal size, composition, palatability and timing. the overweight athlete effect of food composition, meal size and exercise The TEF can last for several hours after a meal and will depend on the amount of energy consumed and the composition of the meal. In general, the thermic effect of a mixed meal is estimated to be 6–10% of total daily energy intake; however, the total TEF will also depend on the macronutrient composition of the diet. For example, the thermogenic effect of glucose is 5–10%, fat is 3–5% and protein is 20–30% (Flatt 1992). Carbohydrate and fat have a lower thermic effect than protein because less energy is required to process, transport and convert carbohydrate and fat into their respective storage forms. Conversely, protein synthesis and metabolism are more energy demanding. Thus, diets higher in fat will have a lower TEF than diets that contain more carbohydrate or protein. In addition, a diet high in energy will have a higher TEF than a diet lower in energy because there is more food to be digested, transported and stored. For example, the TEF of an individual who consumes 12.6 MJ (3000 kcal) daily would be approximately 756–1260 kJ · day–1 (180–300 kcal · day–1), while an individual consuming only 6.3 MJ (1500 kcal) daily would have a TEF of 378–630 kJ · day–1 (90–150 kcal · day–1). The total TEF for a day does not appear to be inﬂuenced by meal size or number, as long as the same amount of energy is consumed throughout the day (Belko & Barbieri 1987). Thus, the TEF will depend both on the amount of energy consumed each day and the composition of this energy. Although exercise may inﬂuence the TEF, there are few data available on the effect of exercise before and after a meal in trained athletes. One study in trained swimmers reported that 45 min of swimming signiﬁcantly increased the metabolic response to a meal when the meal preceded the exercise (104.2 kJ · h–1, 24.8 kcal · h–1) compared with no exercise (84.8 kJ · h–1, 20.2 kcal · h–1) (Nichols et al. 1988). However, this difference is so small that its long-term signiﬁcance on energy regulation is negligible, especially considering the high variability in the termic effect of 475 a meal (TEM) measurement between individuals. Similar results are reported by Bahr (1992), who exercised physically active males for 80 min . at 75% Vo2max. and measured oxygen consumption after exercise. In the treatment condition subjects were fed a meal 2 h after exercise, while subjects fasted in the control condition. They found only a 42-kJ (10-kcal) difference between the two conditions over a 5-h postexercise period. Measurement of energy expenditure Energy expenditure can be measured in the laboratory or estimated using prediction equations. Since access to a laboratory for the measurement of energy expenditure (calorimetry or doubly labelled water) may be limited, this review will focus on the prediction methods used to estimate energy expenditure. pr edic ting ener g y expenditur e One of the most commonly used methods for estimating TDEE is to predict RMR using a prediction equation and then multiply RMR by an appropriate activity factor (Food and Nutrition Board 1989; Montoye et al. 1996). A number of prediction equations have been developed to estimate RMR, but most have been developed using sedentary populations. To date, no equation has been developed to predict the RMR of athletes who may spend hours in training each week. Some of the commonly used RMR prediction equations and the population from which these equations were derived are discussed below. To determine which of these equations work best for athletes, Thompson and Manore (1996) compared the measured RMR values from indirect calorimetry with predicted RMR values using the following equations. In all these equations, weight (wt) was measured in kilograms, height (ht) in centimetres and age in years; LBM stands for lean body mass. • Harris and Benedict (1919); based on 239 subjects, 136 men (mean age, 27 ± 9 years; mean weight, 64 ± 10 kg) and 103 women (mean age, 476 practical issues 33 ± 14 years; mean weight, 56.5 ± 11.5 kg), including trained male athletes. Harris and Benedict derived different equations for both men and women: Males: RMR = 66.47 + 13.75 (wt) – 5 (ht) – 6.76 (age) Females: RMR = 655.1 9.56 (wt) + 1.85 (ht) – 4.68 (age) • Owen et al. (1986); based on 44 lean and obese women, eight of whom were trained athletes (age range, 18–65 years; weight range, 48– 143 kg), none of whom were menstruating during the study, and all of whom were weight stable for at least 1 month: Active females: RMR = 50.4 + 21.1 (wt) Inactive females: RMR = 795 + 7.18 (wt) • Owen et al. (1987); based on 60 lean and obese men (age range, 18–82 years; weight range, 60–171 kg), none of whom were athletes, and all of whom were weight stable for at least 1 month: Males: RMR = 290 + 22.3 (LBM) Males: RMR = 879 + 10.2 (wt) • Mifﬂin et al. (1990); based on 498 healthy lean and obese subjects, 247 females and 251 males (age range, 18–78 years; weight range, 46–120 kg for women and 58–143 kg for men); no mention was made of physical activity level: RMR = 9.99 (wt) + 6.25 (ht) – 4.92 (age) + 166 (sex; male = 1, female = 0) – 161 • Cunningham (1980); based on 223 subjects, 120 males and 103 females, from the Harris and Benedict data base. Cunningham eliminated 16 males who were identiﬁed as trained athletes. In this study, LBM accounted for 70% of the variability of RMR. LBM was not calculated in the Harris–Benedict equation, so Cunningham estimated LBM based on body mass and age: RMR = 500 + 22 (LBM) Thompson and Manore (1996) found that for both male and female athletes the Cunning- ham equation best predicted RMR, with the Harris–Benedict equation being the next best predictor. Because the Cunningham equation requires the measurement of FFM, the Harris–Benedict equation will be easier to use in settings where FFM cannot be measured. Once RMR has been estimated, TDEE can then be estimated by a variety of different factorial methods. These methods vary in how labour intensive they are to use and the level of respondent burden. A detailed description of these methods is given elsewhere (Food and Nutrition Board 1989; Schutz & Jequier 1994; Montoye et al. 1996). The easiest method multiplies RMR by an appropriate activity factor, with the resulting value representing TDEE (Food and Nutrition Board 1989). Another method estimates a general activity factor (GAF) and a speciﬁc activity factor (SAF). The GAF represents the energy expended in doing everyday activities such as walking, standing, driving, and watching television. The SAF is the amount of activity expended in speciﬁc exercises (e.g. running, swimming or weight training) for a designated intensity and amount of time. The SAF is calculated by multiplying the amount of time spent in an activity by its energy requirement (Berning & Steen 1991; Montoye et al. 1996). The GAF and SAF are then added together to get the total amount of energy expended per day in activity. This value is added to the estimated RMR value, then an additional 6–10% is added to represent the TEF. The ﬁnal number then represents the TDEE. This method is relatively easy to use with athletes who have speciﬁc training or exercise programmes and who already keep training logs. TDEE can also be estimated by recording all activities over a 24-h period and then calculating the energy expended in each of these activities (kJ · kg–1 · min–1). The amount of energy expended in each activity is then added and represents TDEE. Many computer programs calculate energy expenditure in this way. Regardless of the method used, keep in mind that all values are estimates. The accuracy of these values will depend on a number of factors: the accuracy of the activity records, the accuracy of the data base the overweight athlete used, and the accuracy with which the calculations are done. Energy intake Since energy intake is one part of the energy balance equation, knowing total energy intake will give some indication of TDEE if body weight is stable. The assessment of dietary records is one of the most frequently used procedures for monitoring the energy and nutrient intakes of athletes. The goal of assessing dietary intake is to achieve the most accurate description of the athlete’s typical food intake. This information is then used to assess mean energy intake and composition of the diet, make recommendations for improving food habits and adjusting energy intake, and determine the need for micronutrient supplements while dieting. methods for collecting energy and nutrient intake data For the athlete with limited time and skills for recording food intake, retrospective methods, such as 24-h diet recalls, food frequency questionnaires or diet histories, can be used. If more speciﬁc energy or nutrient intake data are needed, food records or weighed food records should be used. Deciding which method to use will depend on the capabilities and dedication of the athlete, and the detail and speciﬁcity of the data required by the sports medicine team (Dwyer 1999). The diet record is probably the most frequently used method for assessing the energy and nutrient intake of athletes. A diet record is a list of all food consumed over a speciﬁed time, such as 3–7 days. To more accurately predict energy and nutrient intakes, it is best if foods consumed can be weighed or measured, labels of convenience foods saved, and all supplements recorded from the label. This method also allows for the gathering of more in-depth information such as the time, place, feelings, and behaviours associated with eating. The dietitian working with the athlete can review the diet record to ensure its 477 accuracy. A primary drawback of this method is the tendency for individuals to change their ‘typical eating habits’ on days they record food intake. This method is also more time consuming than a 24-h recall; thus, the accuracy of the diet record depends on the individual’s cooperation and skill in recording foods properly. How many days must be recorded to give an accurate picture of an athlete’s diet? Diet records lasting from 3 to 14 days will provide good estimates of energy and nutrient intakes (Schlundt 1988). Within this range, reliability and accuracy appear to increase with each additional day up to 7 days. Thus, a 7-day diet record can give accurate data for energy and most nutrients. One advantage of the 7-day diet record is that it encompasses all the days of the week, including the dietary changes that frequently occur on weekends and the athlete’s weekly training routine. The disadvantage of this method is that as the number of days increases, so does the respondent burden. If only 3–4-day diet records are used, care should be taken in choosing which days will be recorded. Practical guidelines for achieving a competitive body weight For the overweight athlete, any weight loss attempt should be aimed at achieving a competitive body weight and composition that is optimal for performance and health. What is an optimal body weight for performance? How is this number determined? Who determines this goal? These are difﬁcult questions that need to be addressed by the athlete in consultation with the sports medicine team before a weight loss programme can begin. If the athlete is young and still growing, these questions are even harder. Table 35.1 gives ranges of relative body fat levels for elite athletes in various sports; Berning and . Steen (1998) also give body fat and Vo2max. data for athletes of varying ages. These ranges, however, do not take into account individual variability regarding body fat and performance. In addition, some athletes will perform at their best outside of these ranges. Remember that a 478 practical issues certain amount of body fat is essential for good health. Finally, the inherent error of body composition assessment, 1–3% under ideal conditions, must be considered (Wilmore 1992a). Weight loss goals The following outline offers some criteria and questions that may be helpful in determining an athlete’s optimal body weight. 1 Put emphasis on personal health and well being, and ﬁtness and performance goals — not only weight. • Set realistic weight goals. (What is your current weight goal? Is body weight reduction necessary? Is there any indication that weight loss will improve performance? Have you ever maintained your goal weight without dieting? When was the last time you were at your goal weight? At what weight or body-fat level do you perform well, do you feel good and are you injury free? What was the last weight you could maintain without constantly dieting?) • Place less focus on the scale and more on changes in body composition and lifestyle, such as stress management and making good food choices. • Pick the appropriate weight loss technique that works with your training schedule. Weight loss should be gradual, at approximately 0.5–1.0 kg · week-1. • Mark progress by measuring changes in ﬁtness level and performance levels (personal record times, level of fatigue at the end of a workout, level of energy at the end of the day, strength and power changes), and general overall well-being. 2 Make changes in diet and eating behaviour. • Do not starve yourself or restrict energy too severely. Do not go below 5–6.4 MJ (1200– 1500 kcal) daily for women and 6.4–7.6 MJ (1500–1800 kcal) daily for men. • Do not constantly deprive yourself of favourite foods or set unrealistic dietary rules. • Make basic dietary changes that moderately reduce energy intake, that ﬁt into your lifestyle, and that you know you can achieve. • Reduce fat intake but remember, a lower fat diet will not guarantee weight loss if a negative energy balance is not achieved. • Eat more whole grains, cereals, fruits, and vegetables, and get adequate ﬁbre (> 25 g · day-1). • Do not skip meals and do not let yourself get too hungry. Eat something for breakfast. This will prevent you from being too hungry and overeating later in the day. • Reduce or eliminate late night eating. • Plan ahead and be prepared for when you might get hungry. Carry healthy snacks with you. Always eat high carbohydrate foods immediately after strenuous exercise. • Identify your dietary weaknesses; plan a strategy for dealing with these difﬁcult times. Are you eating when you are bored, depressed, upset? Do you overeat when you are around food or eat out? • Do not go into a training session or competition without eating adequately. Be sure you are well fed both before and after you exercise. 3 Make changes in exercise behaviour. • If you do not already do aerobic exercise and strength training, start and maintain an exercise programme that includes both of these components. This is an absolute requirement for burning fat and the maintenance of a healthy competitive body weight. Strength training will help maintain FFM while you are working to lose body fat. • Plan regular exercise into your day (outside your training sessions) and add additional exercise by walking instead of driving, or using the stairs instead of the elevator. (Adapted from Burke 1995; Manore 1996.) Optimal body weight should be a weight that promotes both good health and performance, and is ‘reasonable’ to achieve and maintain. If an athlete has never been able to achieve or maintain his or her goal weight, then this may be an unrealistic weight that places them under unnecessary psychological stress. Determination of an athlete’s optimal weight must also consider the genetic background, age, gender, sport, health and past weight history. For the female athlete, the overweight athlete knowing menstrual history will also be important in setting weight loss and dietary goals (Dueck et al. 1996). Body composition should be measured and weight loss goals centred on the loss of body fat instead of just weight. This way the goal is shifted to changes in body composition instead of weight (Table 35.1). Knowing body composition also helps prevent the athlete from losing too much weight or setting an unachievable goal. This information can then be used to determine an optimal body weight and to set fat loss goals. For the athlete who is already lean, yet wants to diet, this process can help convince him or her Table 35.1 Ranges of relative body fat for men and women athletes in various sports. From Wilmore (1992b), with permission. Sport Men Women Baseball, softball Basketball Body building Canoeing and kayaking Cycling Fencing Football Golf Gymnastics Horse racing Ice and ﬁeld hockey Orienteering Pentathlon Racketball Rowing Rugby Skating Ski jumping Skiing Soccer Swimming Synchronized swimming Tennis Track and ﬁeld Field events Running events Triathlon Volleyball Weightlifting Wrestling 8–14 6–12 5–8 6–12 5–11 8–12 6–18 10–16 5–12 6–12 8–16 5–12 — 6–14 6–14 6–16 5–12 7–15 7–15 6–14 6–12 — 6–14 12–18 10–16 6–12 10–16 8–15 10–16 — 12–20 8–16 10–16 12–18 8–16 8–15 10–18 8–16 — 8–16 10–18 10–18 10–18 10–18 10–18 10–20 8–18 5–12 5–12 7–15 5–12 5–16 12–20 8–15 8–15 10–18 10–18 — 479 that weight loss is not necessary. Weight loss in a lean athlete is not possible without seriously compromising performance because of the inevitable loss of FFM. These athletes will beneﬁt more from establishing good dietary practices than from weight loss. These guidelines can also be used with the young athlete who does not want to gain weight even though growth and weight gain should be occurring. Role of diet If the athlete does need to lose weight (body fat), a weight loss plan needs to be developed early in the athlete’s training programme to avoid potentially harmful dieting practices and weight cycling. Weight loss is not recommended during periods of intense endurance training; athletes cannot be expected to train intensely and improve performance on low energy intakes. Thus, weight loss goals should be set at approximately 0.5–1 kg · week–1, depending on body size and gender, and focus on decreases in body fat, while maintaining or increasing FFM (Wilmore 1992b; Fogelholm 1994). The degree of energy restriction will depend on body size, typical energy intake and expenditure, and the period allotted for weight loss. In general, reducing energy intake by 10–25% (approximately 1680–3360 kJ or 400–800 kcal daily) may be all that is necessary. If the weight loss is occurring in the off season, then both the restriction of energy intake and increased energy expenditure need to occur. Severe energy restriction or fasting should not be used with athletes. This approach to weight loss only decreases carbohydrate and protein intake and, thus, the ability to replace muscle glycogen (Bogardus et al. 1981) and repair and build muscle tissue after exercise. These types of diets also increase the risk of injury and the feelings of fatigue after routine workouts, which in turn can dramatically undermine self-conﬁdence and performance. Finally, these diets increase FFM losses and decrease RMR (Donnelly et al. 1994; Thompson et al. 1996). These factors, combined with the feelings of deprivation that 480 practical issues accompany severe dieting, usually result in diet failure or relapse. If energy intake decreases below 7.6–8 MJ · day–1 (1800–1900 kcal · day–1), nutrient intakes can be severely compromised (Beals & Manore 1994, 1998; Manore 1996). This level of energy intake is not adequate to replace muscle glycogen and fuel the athlete during intense training periods. Athletes have higher protein and carbohydrate requirements than their sedentary counterparts (Coyle 1995; Lemon 1995). When dieting, carbohydrate intake should remain as high as possible (60–70% of energy) and protein intake at 1.2–1.8 g · kg–1 body weight (Lemon 1995), while fat intake is reduced to 15–25% of energy. Prolonged energy restriction also places that athlete at risk for low dietary intakes of calcium, iron, magnesium, zinc and B complex vitamins (Manore 1996; Beals & Manore, 1998). Thus, it may be necessary for athletes to use vitamin and mineral supplements during long periods of energy restriction (> 3–4 weeks). This may be especially true if the athlete makes poor food choices, eats primarily processed or convenience foods, or eliminates various food groups from the diet. Any weight loss plan for an athlete should moderately reduce energy intake while teaching good food choices. It is much easier to teach athletes how to eliminate or reduce high fat and energy dense foods from their diet than to count kilocalories. They also need to become aware of the situations and emotions that trigger overeating or binge eating. Athletes need to learn the nutrient composition of the foods they eat and why they eat them. This knowledge is useful in developing a diet plan around better food choices, training schedules, budgets and periods when overeating is most likely to occur. Role of exercise Exercise is necessary for both weight loss and weight maintenance. Unlike the general population, most athletes participate in hard physical activity. However, which activities are best for fat loss? It is well documented that aerobic activity oxidizes fat; however, recent evidence indicates that high-intensity anaerobic activity added to an aerobic exercise programme may be better at reducing body fat than aerobic-only exercise (Trembly et al. 1994). Weight training can also help preserve FFM and strength while dieting if energy restriction is not too severe (Donnelly et al. 1994). Thus, the type of exercise added to a weight-loss programme will depend on the current training practices of the athlete. Behaviour modiﬁcation and weight maintenance In order for weight loss to be maintained, changes in diet and exercise habits need to become part of the athlete’s lifestyle. Foreyt and Goodrick (1993) and Klem et al. (1996) found that individuals who are successful at losing and maintaining weight loss have the following characteristics in common: they modify diet, especially energy intake from fat; they exercise regularly and monitor their weight; and they have high levels of social support from family and friends. These changes can be achieved by ﬁrst identifying the eating or exercise behaviour that needs to be changed, then setting speciﬁc and realistic goals for changing this behaviour. Changes in behaviour should be made slowly and modiﬁed as necessary. Finally, successful behaviour is rewarded. This approach to weight loss and maintenance will take time and may require continuous social and professional support (Foreyt & Goodrick 1991). Conclusion Successfully guiding the overweight athlete through the weight loss process is a challenge for both the athlete and the sports medicine team. Identifying the appropriate weight loss goal and method is imperative for a successful outcome. These basic considerations need to be remembered before beginning any weight loss programme: • Both energy intake and expenditure are important. If energy intake is less than energy expendi- the overweight athlete ture, weight will be lost. Increases in energy expenditure and moderate decreases in energy intake may help preserve FFM and muscle strength while dieting. • Rate of weight loss is important. Do not use severe energy restriction or fasting as a means of weight loss. For most athletes, a weight loss of 0.5–1 kg · week–1 is the maximum recommended. • Composition of the diet is important, especially for weight maintenance. Carbohydrate, protein and alcohol oxidation appear to match their energy intake, while fat oxidation does not. • The protein/energy intake ratio is important. When energy intake is low, a higher protein/energy ratio is required. In addition, athletes have higher protein requirement than sedentary individuals. • Micronutrients are important. 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