Low Energy Availability and Relative Energy Deficiency in Sport: What Every Athlete Needs to Know
Are You Fueling Enough to Perform at Your Best?
For endurance athletes and those in weight-class or aesthetic sports, balancing nutrition and training is crucial. But what happens when you’re unintentionally under-fueling? A recent systematic review and meta-analysis sheds light on the risks of low energy availability (LEA) and Relative Energy Deficiency in Sport (RED-S)—conditions that can compromise performance, recovery, and long-term health.
Let’s dive into the research and what it means for athletes striving for peak performance.
Research Deep Dive: The Impact of LEA and RED-S
A large-scale systematic review analyzed 59 studies involving over 6,100 athletes across various sports. The goal? To examine how common LEA and RED-S are and how they impact performance and injury risk.
What is Low Energy Availability (LEA)?
LEA occurs when an athlete doesn’t consume enough energy (calories) to meet both training demands and basic physiological functions like hormone regulation, bone maintenance, and immune function.
What is Relative Energy Deficiency in Sport (RED-S)?
RED-S is a more severe condition resulting from chronic LEA. It was first identified by the International Olympic Committee and can affect all athletes regardless of gender.
How Does RED-S Affect Athletes?
RED-S can impact nearly every system in the body, leading to:
Chronic elevated cortisol levels—increased stress response
Dysregulated sex hormones—low testosterone in men and decreased estrogen in women
Amenorrhea—loss of period in female athletes
Poor bone health—Increased risk of bone stress injuries and stress fractures
Impaired recovery—Greater risk of overuse injuries
Mental health struggles—Increased risk of depression and anxiety
Reduced performance—Slower times, poor endurance, impaired coordination and judgment
Key Findings
44.7% of athletes had LEA—including 49.4% of male athletes and 44.2% of female athletes.
63% of athletes in a subset of studies were at risk for RED-S.
Athletes with LEA experienced:
Decreased running performance, endurance, and training response
Impaired coordination, concentration, and judgment
Increased illness-related absences from training
Decreased bone health and higher rates of stress fractures
This research confirms what sports dietitians and physiologists have observed: under-fueling doesn’t just lead to short-term fatigue—it can cause lasting damage to an athlete’s health and career.
Why This Matters for Athletes
The findings highlight the importance of early detection and prevention of LEA to avoid the more severe consequences of RED-S.
The Solution? Prioritizing Proper Fueling
Your body isn’t just burning calories for workouts. It needs energy for:
Muscle recovery and growth
Bone strength and repair
Hormone regulation (testosterone, estrogen, cortisol balance)
Cognitive function (decision-making, reaction time, focus)
If you’re constantly exhausted, struggling with injuries, or feeling mentally burned out, you may be under-fueling.
How to Detect and Prevent LEA
Since LEA often goes unnoticed, athletes and coaches should use screening tools to identify those at risk.
✔️ The LEAF-Q (Low Energy Availability in Females Questionnaire) is a validated tool for identifying female athletes with potential LEA.
✔️ Tracking menstrual health (for female athletes) is essential—amenorrhea (loss of a period for 3+ months) is a major red flag for RED-S.
✔️ Paying attention to performance and recovery trends—if you’re struggling with fatigue, poor training adaptation, frequent illness, or slow injury healing, it’s time to assess your fueling strategy.
✔️ Working with a sports dietitian to optimize intake and ensure you’re getting the right balance of carbohydrates, protein, and fats to support both performance and long-term health.
Key Takeaways
🔹 Food fuels your performance. Your body needs enough energy from your diet to power your training, recovery, and essential functions.
🔹 Under-fueling is more common than you think. Nearly half of all athletes in endurance, aesthetic, and weight-class sports may be at risk for LEA.
🔹 Long-term consequences can be serious. From bone fractures to hormone imbalances and mental health struggles, RED-S can end athletic careers if not addressed early.
🔹 Preventative screening and proper nutrition strategies can help. If you suspect LEA, take action before it escalates to RED-S.
Need Help Fueling for Performance?
If you’re unsure whether you’re eating enough to meet your training demands, I can help. As a Board Certified Specialist in Sports Nutrition, I work with endurance athletes to create personalized fueling strategies that enhance performance and prevent energy deficiencies.
Click Here to book a discovery call and start optimizing your nutrition for long-term success.
Let’s make sure you’re fueling stronger, smarter, and healthier—so you can perform at your peak without burnout or injury.