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Relative Energy Deficiency in Sport

Alice Brown. Physiotherapist

RED-S describes a condition characterised by low energy availability.

This can have a negative effect on not only athletic performance, but also on the health and functioning of other body systems (such as cardiovascular, skeletal, gastrointestinal or immune).

Low energy availability can lead to the two other pillars that define the phenomenon – menstrual disturbances (for females) and osteoporosis (low bone mineral density).

Is it the same as the female athlete triad?

RED-S is a broader adaptation of the triad. RED-S acknowledges that the resultant issues from the condition are not gender exclusive, and also recognises the spectrum it can exist on rather than the clinical end points described in the triad.

Who is at risk of developing RED-S?

All athletes can be at risk of developing RED-S, however there are some groups who are more prone to this diagnosis. This includes:

  • Females
  • Athletes involved in sports where low body weight and lean physique are advantageous (eg dancing, long distance running, endurance sports such as triathlon)

What are the some of the symptoms of RED-S?

  • Menstrual changes (in females)
  • Recurrent injury (soft tissue or bone)
  • Recurrent illness
  • Unexpected fatigue
  • Disrupted sleep patterns
  • Unexplained changes in mood
  • Problematic relationship with food / training
  • Stagnation or deterioration of performance

What is “low energy availability”

Put simply, it is when Energy In (e.g. food) < Energy Out (e.g. training/activity  demands)

When energy available = energy used, the body is in equilibrium. A state of low energy availability will become an issue one of two scenarios:

  • Training load is NORMAL, but energy availability is LOW (ie. the athlete isn’t fuelling sufficiently for the demands of training)
  • Training load is HIGH and energy availability is LOW


So do I just need to eat more?

Nutrition certainly plays a role in the management or prevention of RED-S, however it’s not just about how much you eat – the type of food and timing of meals can be key in ensuring your body has adequate energy available for the activities you participate in.

Factors outside nutrition are also important to consider (such as training load, individual and environmental factors that could be contributing to RED-S developing).


What are the consequences of low energy availability?


Low energy availability can dampen the expression of hormones in the reproductive system (namely oestrogen and testosterone). For females, clinically this presents as disturbances in menstrual function (causing the cycle to be missed or absent entirely).

Low energy availability (particularly when in combination with menstrual dysfuction) will also decrease the speed of bone turnover by the body, resulting in lower bone mineral density (ie. weaker bones that are more prone to stress injury).

How is RED-S managed?

Best practice management of athletes presenting with RED-S involves a multidisciplinary approach including sports physician, dietitian, endocrinologist, physiotherapist and if applicable, psychologist input. Each profession plays a role in identifying and managing different factors that have contributed to the development of RED-S or are resultant of its presence.

Zone 34 Physiotherapists

David Hillard

David Hillard


Nicole Baer

Nicole Baer

Gloria Spratt

Gloria Spratt

Bernadette Petzel

Bernadette Petzel

Simon Hall

Simon Hall

Alice Brown

Alice Brown


Keay, N., & Francis, G. (2019) Infographic. Energy availability: concept, control and consequences in relative energy deficiency in sport (RED-S). British Journal of Sports Medicine, 53(20), 1310.

Mountjoy, M., Sundgot-Borgen, J.K., Burke, L.M., Ackerman, K.E., Blauwet, C., … & Budgett, R. (2018) IOC consensus statement on relative energy deficiency in sport (RED-S): 2018 update. British Journal of Sports Medicine, 52, 687-697.