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Do you exercise? You need to know about Low Energy Availability (LEA)...

Low energy availability (LEA) can be quite common and is well researched in athletes. In recent years, with an increase in ‘diet and fitness culture’ trends, which are seen in many aspects of modern life, signs of LEA are becoming more apparent in the ‘health and fitness’ focused population and recreational athletes.

What is LEA?

Low energy availability (LEA) is essentially a state in which there is insufficient energy to support physiological function to promote optimal health. Insufficient energy intake can disrupt normal bodily functions and the energy demands of exercise can worsen this.

LEA can occur through either a combination of decreased energy intake (less food), increased energy expenditure via exercise (more exercise) or a combination of both. LEA is underpinned by the concept of energy availability (EA)(1).

Energy Availability (kcal/kg FFM/day) = Energy Intake – Exercise Energy Expenditure/Fat Free Mass (FFM)

For example:

Jim eats 2500 kcal/day and completes a tough training session where he expends 1000 kcal. His fat free mass (FFM) is 70kg.

EA = 2500 - 1000 = 1500

We then divide this by Jim’s FFM.

EA = 1500/70 = 21.5 kcal/kg FFM/day (Generally EA = 45 kcal/kg FFM/day for optimal health)(2)

*It is important to note that this type of calculation is not always as simple in practice, due to constraints with measuring EEE and FFM accurately in a non-clinical setting. The duration of time in LEA must be considered too. However, it can be used as a guide.

What do we know so far?

The concept of LEA initially arose from observations in female athletes and has been extensively investigated in female populations. As a result of this, the female athlete triad was developed in 1997(6), the triad model was updated in 2007(7) and is underpinned by three interrelated components; LEA, menstrual dysfunction and poor bone health.

From more recent studies, it is apparent that the accompanying consequences of this energy deficiency is not just a triad of three components but is a syndrome which affects multiple aspects of physiological function, not just menstrual function and bone health, and its effects can be identified in both males and females(5, 8).

Based on this updated outlook, the International Olympic Committee (IOC) expanded the triad model with the term relative energy deficiency in sports (RED-S) to acknowledge the many associated consequences of LEA on health and performance in both males and females(8). Despite the naming, RED-S is not only seen in athletes, but can be experienced by the wider population.

Who is at risk?

LEA risk is greatest to those who partake in sports where leanness is considered a performance advantage (e.g., cycling, running, gymnastics), those with weight divisions (e.g., boxing and combat sports) and endurance-based events(4, 8, 9). The reasoning behind this is that disordered eating, which can influence energy intake, can be more prevalent in sports where leanness is considered a performance advantage and in sports with weight divisions, thereby increasing participants risk of LEA.

Secondly, endurance-based events are associated with high volumes of training where participants have a large energy expenditure, if energy intake is not increased to meet this demand, it could result in LEA(10).

What are the outcomes of LEA?

While the long-term physiological effects of LEA are thought to affect multiple aspects of human function including bone health, muscle synthesis and breakdown, endocrine and immune systems (seen in the figure below), there is limited research characterising a causal link between LEA and its physiological effects.

LEA is not always associated with weight loss, for example, when energy output is higher than energy input, the body’s own energy reserves can contribute to fuel needs and/or there is reduction of TEE involved with other bodily functions as an evolutionary adaptation (i.e., ‘non-essential’ functions begin to shutdown to conserve energy). It is understood that this inbuilt adaptive mechanism preserves essential bodily functions and tissues during periods of starvation - essentially reducing your TEE in an attempt for the body to decrease the amount of energy required to stay alive(4).

Historically a loss of a menstrual cycle was observed in females suffering with LEA (Female Athlete Triad), however it is now understood there is a vast array of symptoms linked with LEA, and that these are seen in males as well as females.

The figures below give an overview of the health and performances consequences associated with RED-S(5).

Signs of LEA to watch out for:

  • Loss of menstrual cycle (females)

  • Decline in morning erectile function (males)

  • Decrease in sex drive

  • Poor development of muscle mass

  • Issues with sleep

  • Becoming withdrawn and reclusive

  • Lack of concentration

  • Poor recovery between training sessions

  • Digestive issues

  • Recurrent injuries

  • Recurrent infections and illnesses

  • Disordered eating thoughts/tendencies

  • Poor mood

Take home message:

  1. Despite the effects of LEA being observed in females originally, LEA outcomes are seen in males also.

  2. LEA does not only affect the ‘elite’ athletes but is becoming more prevalent in recreational athletes.

  3. Even if you are not losing weight, you can still be under fuelling and susceptible to the effects of LEA.

  4. Both health and sporting performance can be affected by LEA.

This article was written by Sian Law (MSc)


1. Loucks AB, Verdun M, Heath EM (1998) Low energy availability, not stress of exercise, alters LH pulsatility in exercising women. J Appl Physiol 84(1):37-46.

2. Koehler K, Williams NI, Mallinson RJ et al. (2016) Low resting metabolic rate in exercise-associated amenorrhea is not due to a reduced proportion of highly active metabolic tissue compartments. Am J Physiol Endocrinol Metab 311(2):E480-E7.

3. De Souza MJ, Koltun KJ, Williams NI. (2019) The Role of Energy Availability in Reproductive Function in the Female Athlete Triad and Extension of its Effects to Men: An Initial Working Model of a Similar Syndrome in Male Athletes. Sports med 49(Suppl 2):125-5137.

4. Logue DM, Madigan SM, Melin A et al. (2020) Low Energy Availability in Athletes 2020: An Updated Narrative Review of Prevalence, Risk, Within-Day Energy Balance, Knowledge, and Impact on Sports Performance. Nutrients 12(3):835.

5. Mountjoy M, Sundgot-Borgen J, Burke L et al. (2014) International Olympic Committee (IOC) Consensus statement on relative energy deficiency in sport (red-s): 2018 update. Int J Sport Nutr Exerc Metab 28(4):316-31.

6. Otis CL, Drinkwater B, Johnson M et al. (1997) American College of Sports Medicine position stand. The Female Athlete Triad. Med Sci Sports Exerc 29(5):i-ix.

7. Nattiv A, Loucks AB, Manore MM et al. (2007) American College of Sports Medicine position stand. The female athlete triad. Med Sci Sports Exerc 39(10):1867-82.

8. Mountjoy M, Sundgot-Borgen J, Burke L et al. (2014) The IOC consensus statement: beyond the Female Athlete Triad—Relative Energy Deficiency in Sport (RED-S). Br J Sports Med 48(7):491-7.

9. Staal S, Sjödin A, Fahrenholtz I et al. (2018) Low RMR ratio as a Surrogate Marker for Energy Deficiency, the Choice of Predictive Equation Vital for Correctly Identifying Male and Female Ballet Dancers at Risk. Int J Sport Nutr Exerc Metab 28:412–418

10. De Souza MJ, Nattiv A, Joy E et al. (2014) Female Athlete Triad Coalition Consensus Statement on Treatment and Return to Play of the Female Athlete Triad: 1st International Conference held in San Francisco, California, May 2012 and 2nd International Conference held in Indianapolis, Indiana, May 2013. Br J Sports Med 48(4):289

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