What is RED-S and Why Does it Matter?

Rachael Burke 3 September 2021
Relative energy deficiency in sport RED-S athlete nutrition

RED-S stands for "Relative Energy Deficiency in Sport," describing a condition affecting high-performing athletes who don't consume sufficient energy for their activity levels. The fundamental problem is expressed as: Input < Output.

When energy intake falls short of expenditure, the body cannot maintain normal functions. Energy typically reserved for essential bodily processes gets redirected toward athletic performance, creating serious health and performance consequences.

Why RED-S Matters

The condition can reduce:

  • Performance capability
  • Bone density
  • Menstrual function
  • Energy metabolism
  • Infection resistance
  • Protein synthesis
  • Cardiovascular health
  • Psychological well-being

Warning Signs

Athletes may experience:

  • Poor performance despite training
  • Persistent fatigue
  • Recurring injuries (especially tendon-related)
  • Menstrual irregularities
  • Stress fracture history
  • Reluctance to rest
  • Perfectionist behaviours
  • Mood changes including diminished enjoyment of sport

At-Risk Groups

  • Females (over 50% of active exercising females face risk due to menstrual energy losses)
  • Endurance sport athletes with high energy demands
  • Athletes in lean-emphasis sports like gymnastics
  • Those with disordered eating patterns

Support Strategies

Family and friends should recognise athletes' broader value beyond competition, offering encouragement consistently rather than only during victories.

Professional Help

Physiotherapists can identify RED-S risk and coordinate referrals for medical investigation, working with dieticians, nutritionists, and psychologists when needed.