– Written by Margo Mountjoy, Canada, Anna Melin, Sweden, Jorunn Sundgot-Borgen, and Monica Torstveit, Norway

INTRODUCTION

Athletics athletes have significant energy requirements to sustain effective training adaptation and successful competitive performances. In particular, athletes competing in weight-sensitive and leanness-demanding events, are considered an at-risk group for developing Relative Energy Deficiency in Sport (REDs). This can be athletes competing in events in which a low body weight might provide a performance advantage (e.g., anti-gravity disciplines where the power to weight ration is required for success in the event such as high jump and pole vault), or in events requiring high exercise energy expenditure (e.g., endurance disciplines such as long-distance events, marathon, and racewalking)¹. REDs has also been identified in female sprinters². The prevalence of REDs in female and male Athletics athletes ranges between 18-58%, depending on the event³.

WHAT IS REDS?

REDs was first identified in 2014 by the International Olympic Committee (IOC)⁴ as a syndrome of impaired physiological functioning caused by low energy availability (LEA). In 2023, the IOC published an updated consensus statement on REDs to incorporate the interim scientific advances in the field⁵.

The drive to improve sport performance can result in decreased energy availability either through decreasing energy intake through restrictive eating or increasing energy expenditure through excessive exercise. These practices may be motivated by a desire to achieve an ‘ideal’ physique, or to improve power-to-weight ratio. The energy disruption can be either intentional (e.g., erroneous body composition practices, disordered eating behaviour (DE), eating disorders (EDs) or unintentional (e.g., excessive training loads, ignorance of nutritional energy requirements, food insecurity). This mismatch of energy intake and energy expenditure is called LEA. Exposure to LEA that is of prolonged duration or of significant magnitude is termed problematic LEA, which over time, leads to a variety of negative effects on several body systems as well as on sport performance. These health and performance outcomes are the signs and symptoms of the syndrome REDs. According to the 2023 IOC consensus statement⁵, “REDs is a clinically diagnosed, multifactorial syndrome characterised by the accumulation of the deleterious health and performance outcomes resulting from exposure to problematic LEA” and is defined as:

“a syndrome of impaired physiological and/or psychological functioning experienced by female and male athletes that is caused by exposure to problematic (prolonged and/or severe) low energy availability. The detrimental outcomes include, but are not limited to, decreases in energy metabolism, reproductive function, musculoskeletal health, immunity, glycogen synthesis, and cardiovascular and haematological health, which can all individually and synergistically lead to impaired well-being, increased injury risk, and decreased sports performance”⁵.

Health Implications

A conceptual model was developed by the IOC REDs expert writing group to demonstrate the variety of body systems that can be affected in REDs. LEA is situated at the centre of the model as it is the underpinning cause. The graduated arrows depict the time continuum and increasing severity of exposure to LEA which results in the numerous body systems that can potentially be impaired – depending on the athlete’s exposure to LEA, and their physiological moderating and mediating factors (e.g., age, genetics). The body systems in the model were identified in the scientific literature as resulting from exposure to LEA in sports populations. The two body systems with the strongest evidence for impairment are the reproductive and bone systems. It is important to note that all of the body systems listed may have other aetiologies, and thus it is important to rule out other potential causes when diagnosing REDs (i.e., amenorrhea can be also caused by pregnancy or polycystic ovary syndrome). See Figure 1 for the health system consequences of REDs.

Performance Implications

Similarly, a conceptual model depicting the potential sport performance outcomes of REDs was developed by the IOC REDs expert writing group following a review of the scientific literature. See Figure 2 for the sport performance consequences of REDs.

The purpose of these conceptual models is to provide a visual depiction of the health and performance consequences of REDs to raise awareness and educate athletes, coaches, members of the athlete health and performance team, sport scientists, as well as the general public.

Mental Health and REDs

Mental Health Risk Factors for LEA and REDs in Athletics

As mentioned above, suggested risk factors for developing REDs can be both intentional (i.e., when runners and jumpers attempt to achieve low body weight or low percent body fat) and unintentional (i.e., poor nutritional knowledge, lack of resources, increase in training volume without adequate increase in energy intake)⁵.  Athletes who engage in unhealthy dietary behaviours due to body dissatisfaction, drive for thinness, and/or having experienced pressure from a coach or via social media to modify their body composition, are at risk for developing problematic LEA leading to REDs⁶. While REDs can occur in the presence or absence of DE or EDs, exposure to problematic LEA, a history of DE behaviours or an ED increases an athlete’s risk for developing REDs⁵. LEA is often associated with concerns and distress around body weight and shape. The science shows that REDs can occur in all sports, but it occurs more frequently in leanness and weight-sensitive sports such as endurance running and jump events. Thus, participating in these events is also considered a risk factor for developing REDs. Furthermore, pressure to attain an unrealistic body composition (i.e., low body weight or low body fat) has been identified as a form of physical and/or psychological harassment and abuse resulting in the development of REDs and EDs.  Attention must be given to develop safe sport policies and procedures for body composition manipulation to protect athletes from the potential intended or unintended negative outcomes of REDs from erroneous body composition practices⁷. Finally, using safe methods to manipulate body composition in the highest level of elite sport under professional guidance might enhance sport performance⁵. However, without professional supervision including clear policies with respect to screening, consent, methods and data sharing, the improved sport performance results are often short-lived, and can lead to the development of REDs, DE or EDs. Due to the potential negative physical and psychological outcomes from the assessment and manipulation of body composition for performance purposes, this practice is not recommended for athletes under the age of 18 years^{5 6}.

Mental Health Symptoms and Disorders Associated with REDs

Psychological indicators associated with REDs as outcomes from exposure to problematic LEA are cognitive dietary restriction, mood disturbances or fluctuations, perfectionistic tendencies, drive for thinness and reduced sleep quality. Furthermore, depressive symptoms and affective disorders, reduced well-being, primary or secondary exercise dependence/addition, anxiety, the development of DE and EDs,

The psychological risk factors and mental health outcomes described above indicate that action needs to be taken to protect athletes’ health and well-being.

Given these REDs related psychological risk factors and mental health associations, it is essential to include mental health screening when evaluating athletes for REDs, and if REDs is diagnosed, to develop a clinical approach that also manage the psychological consequences.

PREVENTION OF REDS

Primary Prevention

The goal of primary prevention is to identify athletes at risk for REDs before it develops further by implementing prevention strategies targeting the athlete health and performance team (e.g., physicians, physiotherapists, dietitians, psychologists, and physiologists), the athlete entourage (e.g., coaches, parents, and managers), and sports organizations (Figure 3)⁸.

Considering that problematic LEA is the underlying cause of REDs, primary prevention aims to minimise exposure to and reduce behaviours associated with LEA. Important primary prevention strategies are to de-emphasise body weight and leanness as well as to increase awareness and understanding of this syndrome through educational interventions. Body composition and body weight assessment are not recommended for underage athletes, except for medical purposes⁶.  For adult elite Athletics athletes, body composition manipulation may improve performance if implemented under expert supervision with careful planning to ensure realistic body weight/composition goals⁶.

Educational interventions may include topics such as sports nutrition (e.g., the importance of adequate energy availability for health and performance and adequate fuelling strategies for various training durations and intensities), growth and development (e.g., understanding of the maturational changes and nutritional requirements for transition periods such as puberty and physical and mental changes related to adolescence), and media literacy (e.g., awareness of photo retouching and the importance of critical thinking).

Secondary Prevention

The goal of secondary prevention is to identify the REDs signs and symptoms early to facilitate medical intervention to prevent more serious, long-term REDs outcomes, such as an ED or osteoporosis. Secondary prevention strategies can be either self-reported questionnaires (e.g., screening instruments or individual health interviews), or objective assessments (e.g., laboratory tests or imaging) (see Figure 3⁸).

Using validated questionnaires to assess self-reported signs and symptoms are convenient and inexpensive methods to implement to identify signs and symptoms of REDs. One should be aware of the risk of response bias and under-reporting with self-report screening tools. It is therefore recommended to screen for a broad number of symptoms, such as physical symptoms (e.g., menstrual dysfunction in females, reduced erectile function in males, recurrent illnesses, and injuries), psychological symptoms (e.g., mood changes, reduced well-being, depression), and symptoms related to an athlete’s behaviour (e.g., excessive exercise, frequent non-performance-related measurements of body weight or composition, DE behaviours). Considering the limitations of self-report questionnaires, other information-gathering tools, such as personal interviews and/or observation of behaviours from coaches, parents, health personnel or others, may also serve as valuable options to identify REDs signs and symptoms among Athletics athletes. 

Objective assessments for REDs may also be used to identify early signs and symptoms of REDs and to verify self-reported symptoms. To accurately diagnose and determine the severity of REDs, evaluation of multiple REDs signs is necessary. A comprehensive summary of recommended objective indicators of REDs can be found in Table 1 (Primary, Secondary, and Potential indicators of REDs). Of importance to note, endogenous sex hormone levels and menstrual status cannot be reliably determined in individuals taking hormone-based contraceptives. Likewise, thyroid hormone levels are confounded in athletes taking thyroid medication. Laboratory values should be interpreted in comparison with the laboratory-specific reference range and both sex and age related norms⁹. Furthermore, as Athletics athletes with REDs may have body weight or body fat that is under, within, or above the normal reference range, body weight, body mass index, and body fat percentage are not valid indicators of REDs⁸.

DIAGNOSING REDS

As with other multi-system syndromes, there is no single diagnostic test to identify REDs. Clinicians must thus rely on a validated assessment tool to diagnose REDs. The original REDs Clinical Assessment Tool (CAT) was published in 2015¹⁰. Since then, advances in the science of REDs have evolved necessitating an update of the CAT. In 2023, the IOC REDs expert writing group published the second version of the IOC REDs CAT which is scientifically validated and available as a free download for clinical use from the British Journal of Sports Medicine website via the following link https://bjsm.bmj.com/content/57/17/1068, or via a QR code found in Figure 3¹¹.

The IOC REDs CAT2 defines a 3-step process for the diagnosis of REDs.  For screening at-risk populations for REDs, Step 1 includes the implementation of validated, REDs-related screening questionnaires and/or clinical interviews. These may include LEA Questionnaires (e.g., LEAF-Q, LEAM-Q), or an eating disorder questionnaire (e.g., EDE-Q). If the clinician is working with an individual athlete, these questionnaires can be completed as part of the clinical work up. 

Step 2 involves a variety of investigations to identify REDs signs or symptoms, known as primary, secondary, or potential indicators. These terms are defined in Box 1. ‘Primary indicators’ depict an increase severity and risk of REDs and have the most underpinning scientific predictive validity. ‘Secondary indicators’ have less severity/risk and lower measurement validity. Finally, ‘Potential indicators’ have low or inconsistent predictive validity, or lack of availability of a screening tool.  For a complete list of these indicators, please see Table 1.

Next, the collected data points (indicators) are entered into the REDs calculator found in the IOC REDs CAT2 to identify the athlete’s severity/risk of REDs, and to determine their sport participation guidelines. If an athlete is found to be in the green-light zone, the athlete does not have REDs. If the athlete is categorized in the yellow, orange, or red-light zone, REDs is diagnosed following physician assessment to rule out other potential aetiologies or differential diagnoses in Step 3. At this stage, a treatment plan is developed, and sport participation guidelines are implemented. The severity and risk of REDs is on a continuum increasing from yellow to red and athletes can change risk category as they improve through response to treatment over time. See Figure 5 and 6 for more details.

In summary, the IOC REDS expert writing group defines the diagnosis of REDs as:

A diagnosis of REDs results from the clinical assessment by a physician with expertise in REDs, utilising information collected from a multi-disciplinary team (e.g., sports medicine physician, sports dietitian, sports physiologist, sports psychologist/psychiatrist), which ideally includes: 1) appropriately validated questionnaires and/or clinical interview; 2) physical assessment; and 3) laboratory and imaging data as indicated in the IOC REDs Severity/Risk Assessment and Stratification Tool. A REDs diagnosis is predicated on excluding other aetiologies in the differential diagnosis for each REDs indicator and ranges from yellow to orange to red severity/risk.⁹

TREATMENT OF REDS

The objective of treatment of REDs is to promote rehabilitation to prevent severe health consequences of REDs⁷ (Figure 1). The cornerstone of treatment is reversal of problematic LEA, either by increasing energy intake, decreasing exercise energy expenditure or a combination of both. Examples of treatment recommendations in addition to increasing energy availability are presented in Table 2⁷.

The treatment of REDs is multifaceted (Figure 7), and the expected timeline for recovery is variable and depends on the affected body system (Figure 1), the severity, the presence of other medical issues, and the underlying cause of LEA⁷. Independent of the underlying cause, a multidisciplinary treatment approach including medical, nutritional, and psychological support is essential for compliance and treatment outcomes and enables an individual treatment plan that ensures eating practices that support the athlete’s physical and mental health (Figure 7). The dietary counselling should not only address the quantity of energy intake and the timing of food intake around exercise, but also within-day energy balance and food choices to maximize macronutrient and micronutrient availability as well as eating behaviour, special diets, and food intolerances or allergies¹².

The dietary recommendation for increasing energy intake in athletes with problematic LEA is presented in Box 2. The energy intake should be increased with 300-600 kcal/day³ in small increments to avoid unwarranted weight gain¹². Restricted or reduced energy intake most often comes with a concomitant reduction in macronutrients, especially carbohydrate and fat intake⁴. Low carbohydrate intake may not only compromise glycogen stores and performance during high-intensity exercise, but it also has negative effects on sex hormone levels, as well as bone, immune-and iron biomarkers⁴. Therefore, macronutrient needs should be calculated based on macronutrient requirements (g/kg/day) derived from the individual athlete’s training regimen and severity of REDs. Furthermore, the dietary counselling should support the Athletic athlete’s capability of periodizing energy and macronutrient intake to meet varying training demands across the yearly training plan and competition cycle.

Low energy dense diets are common in female athletes with problematic LEA and are associated with an increased drive for thinness and restricted eating behaviour¹² and should be addressed during nutritional counselling (Box 2). Also, increasing energy density of the diet is key if the underlying cause of problematic LEA is poor appetite and/or excessive exercise energy expenditure. An exaggerated dietary fiber intake not only reduces energy density of the food, but it also reduces intestinal energy absorption. Furthermore, dietary fibers prolong satiety, and may therefore limit the energy intake within a meal and delay the return of hunger. Indigestible dietary fibers bind with water in the large intestine and increase satiation because of their bulking effect. Therefore, the general dietary guidelines of absolute dietary fiber intake (e.g., 25-35 g/day) but not relative to energy intake (e.g., g/1000 kcal/day) should be followed (Box 2)¹².

Gastrointestinal symptoms such as bloating and abdominal pain are common among athletes with problematic LEA and EDs⁴ and may inhibit the will power or ability to increase food intake and change dietary behaviours. Medications can be used to improve specific symptoms (e.g., bloating, constipation, diarrhea) on an interim basis until symptoms improve with improvement in energy availability. If symptoms do not improve, it is necessary to clarify whether the symptoms derive from an underlying condition (e.g., coeliac disease), and the registered sports dietitian and medical doctor may aid in narrowing the differential diagnosis or when gastrointestinal specific adjunctive treatment is needed⁷.

CONCLUSION

Given the prevalence of REDs in Athletics athletes, clinicians working with this population should have the clinical competence to prevent, diagnose, and treat REDs. Following the practical guidelines outlined in this article, the athlete health and performance teams will be able to implement strategies to ensure adequate energy availability to optimize both health and sport performances on the track, road and in the field.

Margo Mountjoy M.D., Ph.D.

Professor

Department of Family Medicine, McMaster University, Hamilton, Canada

IOC Medical Commission Games Group, International Olympic Committee, Lausanne, Switzerland

Anna Melin Ph.D.

Professor

Department of Sport Science, Linnaeus University, Kalmar/Växjö, Sweden, Swedish Olympic Committee Research Fellow

Jorunn Sundgot-Borgen Ph.D.

Professor

Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway

Monica Torstveit Ph.D.

Professor

Department of Sport Science and Physical Education, University of Agder, Kristiansand, Norway

Contact: mmsportdoc@mcmaster.ca

References

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