Relative Energy Deficiency
REDs is a condition where an athlete doesn’t take in enough energy (calories) to support both their training and basic bodily functions. It can lead to problems with metabolism, hormone function, menstrual health, bone density, and performance.
RED-S can affect athletes at any level, even high school or recreational athletes, if they are not fueling properly for their activity and daily needs.
RED-S is about energy imbalance, not body size. It can happen at any weight and often goes unnoticed in athletes who appear “healthy.” When you are not giving your body enough fuel, your body will sometimes compensate by shutting down certain systems to save energy. This is why not everyone with RED-S will lose weight.
Amenorrhea (missing your period) is a red flag, not a badge of athletic dedication. It signals that the body isn’t getting enough energy and can harm bone and reproductive health.
REDs affects all genders. Boys and nonbinary athletes can experience hormone disruption, low testosterone, poor recovery, and bone issues too.
While RED-S can coexist with eating disorders, it can also occur unintentionally. Many athletes develop RED-S simply by underestimating how much energy their body truly needs.
Common Causes of REDs
Intentional Restriction
When athletes deliberately eat less, due to dieting, weight goals, or pressure to look a certain way, it can lead to a chronic lack of fuel for both performance and health.
Unintentional Restriction
Without realizing it, athletes may skip meals, underestimate portion sizes, or fail to increase intake as training ramps up. This is often due to busy schedules or lack of nutrition education.
High Training Volume
Training intensely without enough rest or increased nutrition demands more from the body than it can replenish, putting athletes at risk even if eating habits seem “normal.”
Pressures from Society
Messages from coaches, teammates, or media that glorify thinness or promote unrealistic body standards can lead athletes to ignore hunger cues or restrict eating.
Common Signs of REDs
- Fatigue
- Frequent injuries
- Missed periods
- Low bone density
- Poor immune system function
- Gastrointestinal issues
- Irritability
- Mood swings
- Trouble focusing
- Anxiety about food or body
- Plateauing or declining in performance
- Slow recovery
- Reduced strength or endurance
Missing or irregular periods
Reproductive issues
Constant low energy and fatigue
Weak bones and high risk of stress fractures
Frequent injuries and slow recovery
Heart complications
Hormone imbalances
Weakened immune system
Irritability and mood swings
Trouble focusing
Decreased speed, strength, and endurance
Prevention Tips
Fuel Often and Enough
Eat regular meals and snacks throughout the day, especially around training sessions, to give your body the energy it needs for both performance and recovery. Make sure to prioritize fats.
Rest and Recover
Your body needs rest to repair and rebuild. Include rest days, get 8–10 hours of sleep, and avoid overtraining. Recovery is just as important as the workout itself.
Block Out Diet Culture
Challenge harmful messages that glorify thinness, restrict foods, or tie worth to appearance. You don’t have to “earn” your food. Nourishing your body is not optional—it's essential.
Have Open Conversations
Understanding sports nutrition and energy needs can prevent underfueling. Work with a dietitian or healthcare provider, and build a support system that values health over appearance.