Over the past fifteen years, there has been an increase in research on eating pathology in sports [1]. Eating pathology is often described as a continuum ranging from disordered eating (DE) to a clinical eating disorder (ED). DE encompasses symptoms of dysfunctional eating patterns such as fasting, dieting, vomiting, over-eating, binge eating and use of laxatives and/or diet pills [2]. In athletes, DE frequently occurs due to the desire to achieve a sport-specific body-ideal and alleviate sport-specific body dissatisfaction [3]. DE can lead to EDs if left unaddressed and can cause increased incidence of mood, anxiety, and substance abuse disorders [4, 5]. ED are clinical diagnoses that meet DSM-5 criteria, including Anorexia Nervosa (AN), Bulimia Nervosa (BN), and Other Specified Feeding and Eating Disorder (OSFED) [6, 7].
Estimates of the prevalence of DE among athletes varies widely in research due to the different populations of athletes studied (different sports, ages, levels of competitiveness, gender, etc.). In a study of DE amongst elite adolescent athletes by Martinsen et al., 606 Norwegian first year elite sport high school athletes reported higher prevalence of DE compared to the control group [8]. It was found that in the athlete group there was a significantly higher prevalence of DE in females who participated in lean sports compared to males in the same group [8]. Athletes competing in sports such as gymnastics, figure skating, diving, and dancing, where leanness is emphasized, have been found to be at higher risk of DE, which frequently leads to a decrease in sport performance [9].
Perfectionism plays a role in the psychological impact of DE in an athlete, acting both as a symptom and a risk factor for DE [10]. Perfectionism often influences an athlete to have unrealistic expectations, which can result in dissatisfaction with body image and sport performance [5]. Research has found a correlation between DE and perfectionism, with an emphasis on precision and personal expectation for an athlete to achieve a sport-specific body to improve performance [10].
The female athlete triad encompasses three disorders in female athletes: DE, amenorrhea and osteoporosis [11]. This is demonstrated in the desire to lose weight to achieve a sport-specific body ideal, commonly resulting in an energy deficit, which may lead to amenorrhea and osteoporosis. Additionally, this energy deficit will ultimately result in poor performance [10]. A study by Cobb et al. examined 91 competitive female distance runners ages 18–26 years and found that female runners with poor nutrition and irregular eating patterns had an energy imbalance, which often led to amenorrhea [12]. The female athlete triad refers to female athletes of all kinds of sports, regardless of sport type category. While the term ‘female athlete triad’ has been established for many years, more recently the term ‘Relative Energy Deficiency in Sport’ (RED-S) has been used to describe these same three traits coupled with a multitude of other systemic consequences that are associated with low energy availability [13]. RED-S syndrome demonstrates the multitude of physiological consequences associated with DE, such as hematological, cardiovascular, and gastrointestinal disruptions.
Athletes can be divided into lean and non-lean categories. Lean sports emphasize achieving and maintaining a lower body weight due to the belief that lower body weight improves performance [8]. A few examples of lean sports include dancing, judo, long-distance running, swimming, and diving [8, 14]. Alternatively, non-lean sports do not require a low body weight in order for an athlete to be competitive [15]. Some non-lean sports include golf, basketball, table tennis, and horse riding [8]. Lean sports may increase risk for DE because athletes may engage in pathogenic weight-control behavior to achieve a lower body weight [16]. A study by Kong et al. found athletes participating in lean sports scored higher on the Eating Attitudes Test (EAT-26) compared to athletes competing in non-lean sports. Additionally, lean sport athletes reported significantly more eating pathology compared to non-competitive athletes with 84% of the female athletes who screened positive participating in lean sports [15, 17]. Examples of sports that fit into each category, along with categories of sports that make up lean and non-lean sports, are referenced in Fig. 1.
Sports can be further divided into six categories: aesthetic, weight-dependent, endurance, ball game, power, and technical sports [18]. Of these categories, aesthetic, weight-dependent and endurance sports are typically considered lean sports, whereas ball game, power and technical sports are considered non-lean sports.
In aesthetic sports, the performance of an individual or team is assessed by a judge or judges of the competition [19]. In aesthetic sports, the winner is determined by judging an individual or team performance using a complex set of rules [19]. Thus, appearance is a major factor in the judging. Examples of aesthetic sports include gymnastics, diving, figure skating, dancing, ballet [16]. All of these sports are considered lean sports due to the pervasive belief that a lower body weight results in more favorable judging [20].
Weight-dependent sports divide competitors into different categories based on the weight of the competitor. Examples of weight-dependent sports include wrestling, karate, and judo [18]. Studies have shown athletes competing in weight-dependent sports are at an increased risk for eating pathology, such as DE, compared to nonathletes [21]. This is likely due to athletes attempting to achieve lower body weight while maintaining muscle mass to gain a competitive advantage by competing in a lower weight class. Athletes competing in weight-dependent sports may utilize pathogenic weight control behaviors to achieve rapid weight loss prior to a competition in order to achieve higher levels of success [8]. Due to this emphasis on achieving a low body weight, weight-dependent sports can be categorized as lean sports.
Endurance sports include cycling, rowing, running, swimming, cross-country skiing and speed skating [18, 22]. In these sports, a lower body weight is typically associated with a higher level of competition [23]. As a result, endurance athletes may utilize abnormal eating behaviors to achieve a body weight that is too low, resulting in an energy imbalance. This imbalance of energy is a frequent consequence of DE in endurance athletes due to the high metabolic requirements of high-volume aerobic training [22, 24]. Thus, endurance sports can also be categorized as lean sports.
Ball-game sports involve a ball where the objective is to move the ball between members of the same team with a specific goal to score more points than the other team [18]. Ball sports include football, soccer, and volleyball, as well as bat/stick sports (hockey, baseball, cricket) [15, 18]. Ball-game sports are considered non-lean sports as performance is determined by the athlete’s ability to maneuver the ball as desired and thus is not dependent on a specific weight.
Power sports emphasize strength and include powerlifting, shot put, and sprinting [18, 25]. The goal in these sports is to maximize strength and power to improve performance [25]. Appropriate nutrition plays a fundamental role in the athlete’s ability to increase strength and muscle mass for competitive success [25]. Thus, power sports are considered non-lean sports due to this desire to achieve strength.
Technical sports place an emphasis on a certain skill with a piece of specialized equipment [18]. An example of a technical sport is rifle shooting [18]. There has been very little research on eating behaviors in technical sports. However, as this category of sport emphasizes a specific skill and not a specific body type, it can be categorized as a non-lean sport.
Some sports may have higher prevalence rates of DE than other sports, and it is important to consider different activities and focus groups when assessing for prevalence of DE. Athletes who participate in endurance sports have a higher emphasis on aerobic training compared to others [18]. When emphasis is placed on different aspects of training and competition, one can expect an outcome that entices an athlete to continue pursuing the method that allowed them to gain a competitive advantage. In doing so, this may result in the athlete normalizing irregular diet patterns/quantity with respect to their training, resulting in DE.
This systematic literature review is, as far as the authors are aware, first of its kind to date to examine current data in the field of DE in leanness athletes and other activity types to assess for prevalence. It is critical to understand the potential risk factors that are present for athletes, making them susceptible to further health complications. By evaluating the athlete for DE, it facilitates early detection of irregular eating patterns that could lead to ED. This systematic review aims to address the variable prevalence and presentation of DE behaviors in the various types of athletes.
