Undernutrition in Sports - An Underestimated Risk: Relative Energy Deficiency in Sport (RED-S)

Physical performance is a cornerstone of success in sports. But what happens when nutrition can't keep up with the high demands of training? What if athletes, out of fear of gaining weight, avoiding carbs, or subconsciously, just don't eat enough?

The phenomenon of "Relative Energy Deficiency in Sport" (RED-S) is gaining attention in sports science and medicine. RED-S describes the varied health consequences of chronic inadequate energy intake compared to an athlete's energy expenditure. The challenge lies in the fact that RED-S is not always obvious. Often, it remains unnoticed as symptoms are diverse and can mistakenly be attributed to other causes. In this article, we aim to give you an overview of this important topic and raise awareness about particular risks for women.

IOC Consensus Statement

In September 2023, the International Olympic Committee (IOC) released a consensus statement on Relative Energy Deficiency in Sport (RED-S). The full statement is available for download in the British Journal of Sports Medicine.

The statement highlights the risks of RED-S for both professional and recreational athletes who experience prolonged energy deficits. This syndrome affects various bodily functions and athletic performance.

The consensus, informed by an international panel of experts, builds on significant scientific advancements in RED-S over the past five years. The aim is to increase awareness of the syndrome and promote prevention to optimize athlete health, psychological well-being, and performance. The statement specifically highlights:

  • New findings on the role of insufficient carbohydrate intake;
  • The overlap between RED-S and overtraining syndrome;
  • The development process of RED-S;
  • The interplay between mental health and RED-S;
  • Advances in understanding the syndrome among male and para-athletes.

The true extent of RED-S varies across sports, with estimates suggesting that between 15% and 80% of professional athletes may be affected. The syndrome often goes unrecognized by both athletes and their coaches and team doctors and can unintentionally be reinforced by "sports culture," especially by perceived short-term performance gains from limiting calorie intake.

According to Professor Margo Mountjoy, a member of the IOC's Medical and Scientific Commission and lead author of the consensus statement, RED-S is prevalent in various sports for both male and female athletes. Despite a better understanding of the syndrome's causes, awareness of RED-S and its impact on health and performance remains low among athletes, their medical and support teams, and the public.

What is RED-S and What Does it Mean for Recreational Athletes?

RED-S, or "Relative Energy Deficiency in Sport," describes a syndrome where there is an imbalance between energy intake and expenditure in athletes. This syndrome affects not only elite athletes but can also occur in recreational sports, especially when athletes have inadequate diets or engage in excessive training without sufficient recovery periods.

What Are the Consequences of RED-S?

RED-S affects various body functions and systems, potentially leading to decreased athletic performance and health issues. These include hormonal disruptions, reduced bone density, impaired immune function, decreased cardiovascular health, and psychological issues like stress and depression. Over time, this can lead to serious health problems.

 

EDs Performance Conceptual Model. The effects of LEA exist on a continuum. While some exposure to LEA is mild and transient, termed adaptable LEA (arrow depicted in white), problematic LEA is associated with a variety of adverse REDs performance outcomes (arrow depicted in red). LEA, low energy availability; REDs, Relative Energy Deficiency in Sport. September 26, 2023. Protected by copyright.


Typical Warning Signs

  • Absence of menstruation and menstrual irregularities in women.
  • Extended recovery times in training.
  • Performance plateau despite increased training intensity.
  • Fatigue, mood swings, even depression.
  • Digestive problems.
  • Susceptibility to infections.
  • Tendon and muscle pain.
  • Tendon and ligament injuries.
  • Stress fractures.


RED-S in Women – An Underestimated Health Risk

Historically overlooked in sports science, it has now become clear how severe the consequences of inadequate energy intake can be for women.

Claudia Römer, a sports medicine expert at Charité Berlin, has long focused on this widespread phenomenon among elite female athletes and dedicated recreational female athletes. The frequency with which she encounters athletes affected by this condition is alarmingly high. According to Römer, based on international studies, up to 60% of female athletes in certain sports may be affected. "Even among ambitious recreational athletes, we observe very high rates of over 40-50%," she states in the ARD documentary on "The Discovery of Gender Medicine." (German language)

The Female Athlete Triad, a specific manifestation of RED-S, involves excessive training combined with insufficient energy intake, osteoporosis, and menstrual irregularities. This energy deficit can unintentionally arise from rapid training volume increases without corresponding calorie adjustments or from overly ambitious weight loss efforts. Unlike anorexia athletica, RED-S may not necessarily have a psychological component.

To prevent severe health consequences, like low bone density, experts recommend early diagnosis and a conscious approach to energy intake, especially for women. A body fat percentage of not less than 15-17% can serve as a rough guideline. Symptoms such as prolonged recovery times, performance plateaus, fatigue, and digestive issues should be taken seriously and examined by a specialist network to detect RED-S early and prevent long-term damage.

What Does LEA (Low Energy Availability Disruption) Mean?

LEA, or "Low Energy Availability," refers to a state in which the body does not have enough energy to meet both daily metabolic requirements and the additional demands of athletic activity. This state can disrupt various body functions and is closely linked with RED-S. LEA can occur in both athletes and non-athletes when energy intake is insufficient to meet the body's needs.

Source: IOC

What Are the Energy Availability Thresholds?

Energy Availability Thresholds describe the minimum energy requirements needed for the body to sustain essential functions while supporting athletic activities. These thresholds are individual and depend on several factors, including gender, age, body composition, and type of sport. Falling below these thresholds can lead to LEA and subsequently to RED-S. Knowing and monitoring these thresholds is essential to ensure adequate energy supply and minimize the risk of health problems.

Energy Availability Thresholds: Important Guidelines

Energy Availability (EA) is calculated by subtracting energy expended through exercise from energy intake, adjusted for lean body mass:

For example, EA thresholds for physically active women are as follows:

  • A minimum of 188 kJ (45 kcal)/kg lean mass/day is recommended to ensure adequate energy for all physiological functions.
  • Reduced or subclinical energy availability is between 125-188 kJ (30-45 kcal)/kg lean mass/day. This is considered an acceptable range for athletes aiming for short-term weight loss within a well-structured nutrition and training plan.
  • Low energy availability is defined as less than 125 kJ (30 kcal)/kg lean mass/day and indicates an unsafe energy level, potentially leading to adverse health outcomes and sports performance issues.

What Nutritional Strategies Can Be Applied to RED-S?

To counteract RED-S, targeted nutritional strategies are essential:

  • Increase energy intake: Daily calorie intake should be increased, particularly through nutrient-rich foods.
  • Optimize macronutrient distribution: A balanced ratio of carbohydrates, proteins, and fats is important to meet energy needs and support recovery.
  • Adjust carbohydrate intake: Adequate carbohydrate intake before, during, and after exercise is essential to optimize glycogen stores.
  • Ensure protein intervals: Regular protein intake throughout the day helps maintain muscle mass.
  • Ensure micronutrient intake: Sufficient vitamins and minerals are essential to avoid deficiencies. (Micronutrients for bone mineralization: Calcium, Protein, Magnesium, Phosphorus, Vitamin D, Potassium, and Flour)
  • Pay attention to meal timing: Nutrition should be aligned with training to maximize energy availability and support recovery.
  • Optimize fluid intake: Proper hydration is crucial for maintaining physiological functions and performance.
  • Seek nutritional counseling: Professional nutrition counseling can create individual plans tailored to the athlete’s specific needs.

Additionally, training should be reduced, and active stress management should be practiced.