Eating disorder research is lacking in long-term prospective studies, which are key to establishing risk factors. Most research relies on scores from eating attitudes and behavior surveys to determine clinical and subclinical levels of eating disorders. The true incidence of eating disorders is not often measured. The available evidence suggests that eating disorders have multiple associations. Personal characteristics, such as perfectionism, may be predisposing, whereas others factors, such as competitive pressure or injury, may act as triggers or perpetuate the behavior.119,120 Female athletes are more at risk than male athletes, and the risk is higher in some sports than others. Also, eating disorders are more prevalent at higher levels of competition.110,114 Table 9-6 summarizes the risk factors currently being studied by researchers.
Schaal et al30 reported that endurance sports and aesthetic sports had the highest prevalence of eating disorders for women, whereas sports with weight classes have the greatest risk for male athletes.30 However, this distinction may not apply to adolescents, for whom few sport-specific differences have been reported.121 The gender difference is more than just sport related. Eating disorders manifest differently in men and women. Anorexia nervosa is much less common in males than females. Male athletes suffering from eating disorders are striving to gain muscle mass and may view themselves as undersized even when they are not.16 This is known as muscle dysmorphia. Female athletes have a drive for thinness and view themselves as overweight even when they are underweight (Side Bar 9-2).17
Aspects of an athletes personality may place them at a higher risk for an eating disorder. Predisposing factors, such as a high achievement orientation, obsessive compulsive traits, body dissatisfaction, and perfectionism, have been proposed links to disordered eating. The combination
The evidence in athletes is limited, but some cross-sectional studies have shown moderate to strong associations between perfectionism and body dissatisfaction122 and between perfectionism and risk for eating disorders.123
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The presence of a predisposing factor is not enough to initiate an eating disorder. Often, an event triggers an athletes experimentation with behaviors such as fasting, vomiting, or laxative use. That event could be a negative comment from a coach, parent, or teammate or perceived pressure to improve performance. Coaches that focus heavily on leanness as a way to increase ability and closely monitor their athletes weights may push a susceptible athlete toward disordered eating unknowingly.119 Krentz et al120 found that desire for leanness to improve performance was predictive of disordered eating in youth participating in gymnastics, figure skating, diving, and ballet. Injury may be another contributing factor. Athletes who have long recovery periods may gain weight or lose muscle mass while away from training. The desire to make a quick return to sport could spur an athlete to use unhealthy dieting or purging behaviors.
The sport itself may perpetuate disordered eating. Sports that are judged in part based on the physique of the athlete or are meant to be visually pleasing can be categorized as aesthetic sports. Body size and proportion may be important in the skills of the sport, such as in gymnastics where the ability to generate rotational force increases with smaller frames and greater muscle mass. Krentz and Warschburger124 found that adolescents in aesthetic sports had more symptoms of disordered eating than age-matched adolescents who played ball sports. Other sports in which athletes compete in weight classes are also concerning. Wresting and weight lifting emphasize power in the smallest body possible to gain a competitive advantage. Eating disorders in male athletes are most likely to occur in the sports of wrestling, crew, and track.30,106 Recent changes to weigh-in rules in wrestling appeared to decrease the practice of weight cutting in NCAA Division I athletes.125
Early specialization in aesthetic or weight class sports may leave young athletes at a disadvantage if they grow out of the physical characteristics key to those sports.114,119 Efforts to resist puberty-induced growth spurts may lead an athlete to restrictive dieting. Intense training is known to slow the onset of puberty in females. Puberty marks a critical change in how adolescents view their bodies. Postpubescent females had greater body dissatisfaction and restricted between-meal eating than those who were prepubescent, and postpubescent males reported more desire to increase muscle and lose weight than prepubescent males.126 The potential loss of a sport they have been involved with from an early age is an additional threat during an important stage of physical and emotional growth.
Higher levels of competition are thought to increase the prevalence of eating disorders. However, direct comparisons between high school, college, and elite athletes are lacking. There is evidence that adolescents and adults who compete at elite levels in Norway (regional or national teams) have higher rates of eating disorders than their nonathlete peers.110,114 Prevalence among elite adolescents was reported as 7% vs 2.3% of adolescent nonathletes.110 Sundgot-Borgen and Torstveit114 found even great rates of eating disorders in the adult elites (13.5%) with a slightly higher prevalence in nonathletes (4.6%). A comparison of risk factors between elite and nonelite adolescent athletes found that elite females had significantly higher risk than nonelite females, but no differences existed between male athletes.4 Several studies of specific sports show high rates of eating disorders among elite athletes in the United States, but these did not compare prevalence directly to other levels of participation.123,128