What is low energy availability in athletes?

What are the ‘relative energy deficiency in sport’ (RED-S), the ‘athlete triad’ and low energy availability? Definition of concepts and history.

Concepts that deal with the availability of energy in athletes

What is RED-S?

The relative energy deficiency in sport (RED-S) is currently a very hot topic in sports nutrition, and for a good reason. The RED-S is a theoretical model originally defined in 2014 and it is thought to have the potential to explain the origin of a wide range of signs and symptoms that may negatively affect the health and performance of physically active individuals (both males and females). These effects include endocrine, physiological, metabolic, and psychological dysregulations, which are thought to ultimately affect physical capacity and performance.


RED-S explains the origin of a wide range of signs and symptoms that may negatively affect the health and performance of physically active individuals (both males and females)

It is typically said that someone suffers from ‘RED-S’ when a range of these systems shows altered function. The cause of these alterations is thought to be ‘energy availability’ or —specifically— ‘LOW energy availability’ (or LEA, see explanation below).


Banner to show Jose Areta's lecture on RED-S


What is The Triad?

Interestingly, there is another — anteceding — model that also provides a theoretical framework to understand negative effects of LEA, which is the ‘triad’ model. Originally called the ‘female athlete triad’, this model was first mentioned in the literature in 1993 and formally established by a group of experts in 1997. The recognition came in an effort to find a solution to the large incidence of female athletes showing a coexistence of the ‘triad’ of symptoms of menstrual dysfunction, osteoporosis (weakened bones) and eating disorders (reduced energy availability).


Decades of research have provided strong support to this model, and thanks to this we have now a clearer understanding of how to diagnose this condition and what are the typical signs and symptoms. More recently, in the last couple of years, parallels have been drawn between this condition and observations of bone and re