The Prevalence of REDs: How Common Is Relative Energy Deficiency in Sport?

Recent studies suggest that up to 80% of female athletes and 70% of male athletes may experience or be at risk for Relative Energy Deficiency in Sport (REDs), a condition with serious health and performance consequences. This widespread issue, driven by low energy availability, can severely impact an athlete's physical and psychological well-being.

Quick Summary

This article explores the prevalence of Relative Energy Deficiency in Sport (REDs) across various athletic populations, discussing how factors like gender, sport type, and training intensity influence its occurrence.

Key Points

• High Prevalence in Athletes: Studies report that a significant percentage of both male (15–70%) and female (23–80%) athletes are affected by or at risk of REDs.

• Disparity Across Genders: Female athletes tend to have a higher overall prevalence of REDs compared to males, although both genders are impacted.

• Sport-Specific Risk: Aesthetic, weight-class, and endurance sports have higher rates of REDs due to increased pressure to maintain low body weight or high training volume.

• Influencing Factors: Intentional or unintentional low energy availability, psychological stress, and inadequate nutritional knowledge are key drivers of REDs prevalence.

• Diagnostic Challenges: Inconsistent measurement methods and the presence of subclinical symptoms make accurate prevalence estimation and diagnosis difficult in real-world settings.

Understanding the Prevalence of REDs

Relative Energy Deficiency in Sport (REDs) is a functional impairment caused by low energy availability (LEA), where an athlete’s energy intake is insufficient to cover the energy expended during training and daily activities. The prevalence of this condition varies significantly across different athletic populations, genders, and sports. While often associated with the 'Female Athlete Triad,' REDs affects both male and female athletes, with concerningly high rates reported in recent studies. The wide range in reported prevalence rates (e.g., 23–80% in female athletes and 15–70% in male athletes) reflects the challenge in accurate measurement and diagnosis, given that many cases involve subclinical or unreported low energy states.

The Impact of Gender on REDs Prevalence

Research consistently indicates a higher prevalence of REDs among female athletes compared to their male counterparts. This is often linked to societal pressures regarding body image and the historically greater focus on eating disorders in female athletic populations. However, while the risk is higher in females, modern research confirms that males are also significantly affected, a realization that led the International Olympic Committee (IOC) to rebrand the condition from the 'Female Athlete Triad' to the more inclusive REDs in 2014.

Studies show distinct differences in presentation and tolerance levels for low energy states between genders. While hormonal disruptions like amenorrhea are a key indicator in females, male athletes with REDs may present with suppressed reproductive hormones and impaired bone health, often requiring more severe energy deficits before symptoms become apparent. For example, one study on national athletes found a higher risk of REDs in females (41.2%) than males (26%). The continued underestimation of REDs in males, especially in sports that do not emphasize leanness, remains a problem in the athletic community.

Prevalence by Sport Type

The prevalence of REDs is not uniform across all sports but is more concentrated in certain categories based on the physiological and aesthetic demands of the discipline. A crucial distinction is made between sports that emphasize leanness or specific weight classes and those that do not.

High-Risk Sports (aesthetic and weight-sensitive):

• Aesthetic Sports: Gymnastics, figure skating, and dance have a higher reported prevalence due to pressure to maintain a specific appearance.
• Weight-Class Sports: Disciplines like wrestling and lightweight rowing, where athletes restrict calories to 'make weight,' have elevated risk. One study in Malaysian national athletes found that weight-class (23.9%) and intermittent (20.3%) sports had the highest risk prevalence.
• Endurance Sports: Marathon runners and cyclists are at high risk due to the immense energy expenditure of training, making it difficult to maintain adequate energy availability. Some research indicates that up to 65% of ultra-endurance athletes may be at risk.

Lower-Risk Sports (potentially underestimated):

• In some team sports, the risk may be less immediately obvious, but it is still a concern. For example, a study of female football players found a 22% risk of REDs within the cohort. The prevalence can still be significant, particularly due to high-volume training schedules.

Factors Influencing REDs Prevalence

Several interconnected factors contribute to the wide-ranging prevalence of REDs observed in athletic populations. These factors often interact, creating a complex web of risk for an individual athlete.

• Intentional vs. Unintentional Low Energy Availability (LEA): Some athletes intentionally restrict calories for performance or aesthetic reasons, while others unintentionally under-fuel due to a lack of nutritional knowledge or busy schedules. This unintentional LEA can occur when a sudden increase in training volume or intensity is not matched by a corresponding increase in energy intake.
• Psychological Factors: Athletes experiencing anxiety, depression, and disordered eating behaviors are at a higher risk of developing REDs. A study on ultra-endurance athletes noted that psychological factors were often linked to restrictive eating, underscoring the need for mental health support.
• Training Volume and Intensity: The sheer volume and intensity of training required for many sports significantly increase an athlete's energy demands. Failing to meet these demands is a primary driver of LEA.
• Poor Nutritional Knowledge: Inadequate education on proper sports nutrition can lead to poor fueling strategies, especially concerning nutrient timing and overall caloric needs.

Comparison of REDs Indicators by Risk Level

Indicator	Mild REDs Risk	Moderate/High REDs Risk	Very High/Extreme REDs Risk
Primary Indicators	1-2 indicators present	3 primary indicators ± max 1 secondary OR 2 primary and ≥2 secondary	≥4 primary OR 3 primary and ≥2 secondary
Secondary Indicators	≥2 indicators present	-	-
Symptom Examples	Mild fatigue, minor changes in mood, occasional missed training	Persistent fatigue, noticeable performance decline, altered hormone levels	Significant training disruption, severe health consequences, bone stress injuries
Health Implications	Subclinical hormonal changes	Detrimental health effects affecting multiple bodily systems (e.g., bone, reproductive, and metabolic)	Serious long-term consequences on health, potentially irreversible
Performance Effects	Minimal or subtle performance impact	Noticeable decline in performance, reduced muscle strength	Severe performance impairment, increased risk of injury, and decreased endurance

Conclusion

The prevalence of REDs is high among athletic populations, with multiple studies documenting widespread risk across genders and sport types. Female athletes, particularly those in aesthetic and weight-sensitive sports, consistently show higher rates, though male athletes and those in endurance sports are also significantly affected. The wide range in reported prevalence rates underscores the complexities of accurate detection, often involving subclinical symptoms and varied measurement methods. Awareness of REDs indicators, including performance decrements, hormonal imbalances, and psychological changes, is crucial for early identification and intervention. Ultimately, addressing the prevalence of REDs requires a holistic approach that educates athletes, coaches, and sports practitioners on proper nutrition, training load management, and the crucial mind-body connection in athletic health.

Frequently Asked Questions

What is the primary cause of REDs?

The primary cause of Relative Energy Deficiency in Sport (REDs) is low energy availability (LEA), which occurs when an athlete's dietary energy intake is insufficient to support the energy demands of exercise and daily bodily functions.

Are female athletes more affected by REDs than male athletes?

While female athletes often show a higher prevalence of REDs, it affects both genders. Early research focused more on females, but recent studies confirm male athletes are also at significant risk, with some estimates suggesting up to 70% of male athletes could be affected.

Which sports have the highest prevalence of REDs?

Aesthetic sports (like gymnastics), weight-class sports (wrestling), and endurance sports (marathon running, ultra-running) tend to have the highest prevalence of REDs due to the emphasis on low body weight or the immense energy expenditure.

How is the prevalence of REDs measured?

The prevalence of REDs is challenging to measure consistently due to varied methodologies. Researchers use questionnaires (like LEAF-Q and LEAM-Q), physical assessments (bone mineral density), and psychological evaluations to identify risk and indicators of REDs.

Can unintentional under-fueling lead to REDs?

Yes, unintentional low energy availability (LEA) due to factors like busy schedules, inadequate nutritional knowledge, or simply miscalculating caloric needs is a major contributor to REDs, especially during periods of high training volume.

Does REDs only affect elite athletes?

No, REDs can affect athletes of any level, age, or gender. While it is highly prevalent in elite populations, amateurs who increase their training load without adjusting their energy intake are also at risk.

What are the common indicators of REDs?

Common indicators of REDs include fatigue, recurrent illness, increased risk of injury (especially bone stress injuries), hormonal imbalances, irregular menstrual cycles in female athletes, and psychological changes like irritability and anxiety.