Introduction
Energy Availability
Introduction
A fundamental nutrition consideration for athletes is ensuring sufficient energy for the exercise that they are undertaking.
On the other hand, if energy needs are consistently not met, this may have a negative impact on health and performance. The following information will explain the importance of energy, the concepts of energy balance and energy availability, as well as the consequences of inadequate energy availability. Finally, practical solutions will be shared to help female athletes consistently meet their energy needs.
Providing the body with an adequate amount of energy is beneficial to an athlete’s health and performance.
Energy balance
Energy balance refers to the balance between the amount of energy (kilocalories, kcal) consumed through food and drink (i.e., energy intake) and the amount of energy expended by the body (i.e., energy expenditure). Depending on the difference between energy intake and energy expenditure, an athlete can be in an ‘energy deficit’, an ‘energy surplus’ or ‘energy balance’:
Daily energy requirements
There are three main processes which contribute to the body’s total daily energy expenditure (TEE) which are basal metabolic rate, thermic effect of food, and thermic effect of activity. Daily energy intake requirements to ensure energy balance vary from athlete to athlete, mainly dependent on the duration and intensity of exercise.
Energy availability
Energy availability refers to the amount of energy available for bodily physiological and homeostatic processes to function properly, after accounting for the energy expended through exercise (i.e., exercise energy expenditure).
Energy availability is expressed relative to fat free mass, the body’s most metabolically active tissue. The calculation for energy availability is as follows:
The body requires enough energy available for important physiological functions and systems, such as:
Immune system
Reproductive system
Hematological function
Neurocognitive function
Cardiovascular function
Low energy availability (LEA)
Many athletes expend large amounts of energy on a daily basis through undertaking intense training loads. It is important that athletes consistently meet their energy needs to ensure that their body has sufficient energy available to carry out fundamental physiological processes that are important for health, as well as to support their exercise demands. If an athlete’s body consistently does not have enough energy left after exercise to support fundamental physiological functions, this can result in what is known as ‘low energy availability’ (LEA).
LEA is the underlying cause of the conditions known as Relative Energy Deficiency in Sport (REDs) and the Female Athlete Triad. For more about these conditions, see the reference and resources list.
According to the IOC 2023 consensus statement
(Mountjoy et al., 2023), LEA occurs as a continuum between:
1
Adaptable LEA
Exposure to reduced energy availability. Associated with benign effects which are mild and easily reversible, typically having little to no impact on long-term health, well-being or performance.
2
Problematic LEA
Exposure to low energy availability. Associated with greater disruption to body systems, which can potentially cause long-term impairments to health and performance.
Causes of LEA
The fundamental causes of LEA are inadequate energy intake and/or failure to match energy intake to training regimes.
This is demonstrated in mathematical terms in the table below.
Factors contributing to the development of LEA
There are a number of factors which can contribute to the development of LEA, related to either inadequate energy intake or failure to match energy intake to high training load (see below). Through education and awareness, many of these barriers can be addressed to minimize the likelihood of an athlete inadvertently experiencing low energy availability.
Assessing LEA
It is challenging for practitioners to accurately measure all components of energy availability i.e., energy intake, exercise energy expenditure and fat free mass, in particular energy intake and exercise energy expenditure. In turn, this makes it difficult to identify LEA, particularly in the field.
Alternatively, there are several screening tools which have been produced to assess LEA and its associated outcomes. These include:
Low Energy Availability in Females Questionnaire (LEAF-Q)
RED-S Specific Screening Tool (RST)
Eating Disorder Examination Questionnaire (EDE-Q)
Exercise Addiction Inventory (EAI)
Exercise Dependence Scale (EDS)
IOC Relative Energy Deficiency in Sport Clinical Assessment
Tool-2 (IOC
REDs CAT2)
Signs, risk factors and consequences of LEA
It is important for coaches, support staff and athletes to be aware of potential signs and risk factors of LEA in female athletes (see below). It is important to note that the signs and risk factors shown below are not an exhaustive list. In addition, an athlete does not need to show all of these symptoms to be experiencing LEA.
Potential indicators of LEA in female athletes
Menstrual irregularities
or complete loss
of menstrual cycle
Chronic dietary
restriction and/or
extreme dieting
History of
bone stress
injuries
Low bone
mineral
density
Poor recovery
between training
sessions
Clinically diagnosed depression
and/or anxiety
Lack of
ovulation
Urinary
incontinence
Gastrointestinal
symptoms at
rest/during exercise
Reduced or
low resting
metabolic rate
Sleep
disturbances
Increased stress
or anxiety
Exercise dependence/ addiction
Difficulty
concentrating
Perfectionist
tendencies
Frequent
injuries
Training
inconsistencies
Constant
fatigue
See 
, 
and 
for more information on some of the indicators shown above
Health and performance impacts of LEA
The REDs Health/Performance conceptual models (Mountjoy et al., 2023) outline the range of impacts that LEA can cause. The outcomes shown will occur over different time periods, and with differing severities. In addition, the outcomes experienced may differ between individuals.
Please also note that the impacts captured within the conceptual models can occur due to etiologies other than problematic LEA.
Prevalence of LEA
It is suggested that LEA is more likely to occur in certain types of sports:
Aesthetic sports (e.g., gymnastics) and weight sensitive sports (e.g., wrestling, jockeys): potentially due to eating disorders and/or disordered eating* being more prevalent in these sports, which impacts energy intake, thus increasing the risk for LEA. In weight sensitive sports, adaptable LEA may be more common during periods of weight loss in preparation for competition.
Endurance based sports (e.g., running, cycling): potentially due to high volumes of training resulting in increased exercise energy expenditure, which in turn increases the risk for LEA.
*It should be noted that LEA can occur both with and without an eating disorder/disordered eating
LEA: Females vs. males
Both females and males can experience LEA, however research suggests that the prevalence of LEA is higher in female athletes vs. male athletes.
One explanation for this is that the energetic cost of maintaining the reproductive system, as well as gestation, are significantly higher for females in comparison to males. This means that females may be more sensitive to reductions in energy availability, due to the body preserving energy to ensure successful gestation can still occur during periods of LEA.
Research into the endocrine and bone metabolism responses to LEA suggest that females are less resilient to the effects of LEA in comparison to males.
energy availability
References
Çetiner-Okşin, B., Güzel, Y., Aktitiz, S., Koşar, Ş. N., & Turnagöl, H. H. (2023). Energy balance and energy availability of female basketball players during the preparation period. Journal of the American Nutrition Association, 42(8), 807–813.
Civil, R., Lamb, A., Loosmore, D., Ross, L., Livingstone, K., Strachan, F., Dick, J. R., Stevenson, E. J., Brown, M. A., & Witard, O. C. (2018). Assessment of Dietary Intake, Energy Status, and Factors Associated With RED-S in Vocational Female Ballet Students. Frontiers in Nutrition, 5, 136.
Foley Davelaar, C., Ostrom, M., Schulz, J., Trane, K., Wolkin, A., & Granger, G. (2020). Validation of an Age-Appropriate Screening Tool for Female Athlete Triad and Relative Energy Deficiency in Sport in Young Athletes. Cureus, 12(6).
Griffiths, M., Szabo, A., & Terry, A. (2005). The exercise addiction inventory: A quick and easy screening tool for health practitioners. British Journal of Sports Medicine, 39(6), e30.
Hausenblas, H., & Downs, D. (2002). How much is too much? The development and validation of the exercise dependence scale. Psychology and Health, 17(4), 387–404.
Heikura, I. A., Uusitalo, A. L. T., Stellingwerff, T., Bergland, D., Mero, A. A., & Burke, L. M. (2018). Low Energy Availability Is Difficult to Assess but Outcomes Have Large Impact on Bone Injury Rates in Elite Distance Athletes. International Journal of Sport Nutrition and Exercise Metabolism, 28(4), 403–411.
International Olympic Committee Relative Energy Deficiency in Sport Clinical Assessment Tool 2 (IOC REDs CAT2). (2023). British Journal of Sports Medicine, 57(17), 1068.
Jagim, A. R., Fields, J., Magee, M. K., Kerksick, C. M., & Jones, M. T. (2022). Contributing Factors to Low Energy Availability in Female Athletes: A Narrative Review of Energy Availability, Training Demands, Nutrition Barriers, Body Image, and Disordered Eating. Nutrients, 14(5), Article 5.
Keay, N., Francis, G., & Hind, K. (2018). Low energy availability assessed by a sport-specific questionnaire and clinical interview indicative of bone health, endocrine profile and cycling performance in competitive male cyclists. BMJ Open Sport & Exercise Medicine, 4(1).
Klein, D. J., McClain, P., Montemorano, V., & Santacroce, A. (2023). Pre-Season Nutritional Intake and Prevalence of Low Energy Availability in NCAA Division III Collegiate Swimmers. Nutrients, 15(13), 2827.
Logue, D. M., Madigan, S. M., Melin, A., Delahunt, E., Heinen, M., Donnell, S.-J. M., & Corish, C. A. (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.
Luce, K. H., Crowther, J. H., & Pole, M. (2008). Eating Disorder Examination Questionnaire (EDE-Q): Norms for undergraduate women. International Journal of Eating Disorders, 41(3), 273–276.
Melin, A. K., Heikura, I. A., Tenforde, A., & Mountjoy, M. (2019). Energy Availability in Athletics: Health, Performance, and Physique. International Journal of Sport Nutrition and Exercise Metabolism, 29(2), 152–164.
Melin, A., Tornberg, A. B., Skouby, S., Faber, J., Ritz, C., Sjödin, A., & Sundgot-Borgen, J. (2014). The LEAF questionnaire: A screening tool for the identification of female athletes at risk for the female athlete triad. British Journal of Sports Medicine, 48(7), 540–545.
Moss, S. L., Randell, R. K., Burgess, D., Ridley, S., ÓCairealláin, C., Allison, R., & Rollo, I. (2021). Assessment of energy availability and associated risk factors in professional female soccer players. European Journal of Sport Science, 21(6), 861–870.
Mountjoy, M., Ackerman, K. E., Bailey, D. M., Burke, L. M., Constantini, N., Hackney, A. C., Heikura, I. A., Melin, A., Pensgaard, A. M., Stellingwerff, T., Sundgot-Borgen, J. K., Torstveit, M. K., Jacobsen, A. U., Verhagen, E., Budgett, R., Engebretsen, L., & Erdener, U. (2023). 2023 International Olympic Committee’s (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs). British Journal of Sports Medicine, 57(17), 1073–1098.
Mountjoy, M., Sundgot-Borgen, J., Burke, L., Carter, S., Constantini, N., Lebrun, C., Meyer, N., Sherman, R., Steffen, K., Budgett, R., & Ljungqvist, A. (2014). The IOC consensus statement: Beyond the Female Athlete Triad--Relative Energy Deficiency in Sport (RED-S). British Journal of Sports Medicine, 48(7), 491–497.
Papageorgiou, M., Elliott-Sale, K. J., Parsons, A., Tang, J. C. Y., Greeves, J. P., Fraser, W. D., & Sale, C. (2017). Effects of reduced energy availability on bone metabolism in women and men. Bone, 105, 191–199.
Schaal, K., Tiollier, E., Le Meur, Y., Casazza, G., & Hausswirth, C. (2017). Elite synchronized swimmers display decreased energy availability during intensified training. Scandinavian Journal of Medicine & Science in Sports, 27(9), 925–934.
Scheffer, J. H., Dunshea-Mooij, C. A. E., Armstrong, S., MacManus, C., & Kilding, A. E. (2023). Prevalence of low energy availability in 25 New Zealand elite female rowers – A cross sectional study. Journal of Science and Medicine in Sport, 26(12), 640–645.
Torres-McGehee, T. M., Emerson, D. M., Pritchett, K., Moore, E. M., Smith, A. B., & Uriegas, N. A. (2021). Energy Availability With or Without Eating Disorder Risk in Collegiate Female Athletes and Performing Artists. Journal of Athletic Training, 56(9), 993–1002.
Traversa, C., Nyman, D. L. E., & Spriet, L. L. (2022). Dietary Intake over a 7-Day Training and Game Period in Female Varsity Rugby Union Players. Nutrients, 14(11), 2281.
Villa, M., Villa-Vicente, J. G., Seco-Calvo, J., Mielgo-Ayuso, J., & Collado, P. S. (2021). Body Composition, Dietary Intake and the Risk of Low Energy Availability in Elite-Level Competitive Rhythmic Gymnasts. Nutrients, 13(6), 2083.
Woodruff, S. J., & Meloche, R. D. (2013). Energy availability of female varsity volleyball players. International Journal of Sport Nutrition and Exercise Metabolism, 23(1), 24–30.
Zabriskie, H. A., Currier, B. S., Harty, P. S., Stecker, R. A., Jagim, A. R., & Kerksick, C. M. (2019). Energy Status and Body Composition Across a Collegiate Women’s Lacrosse Season. Nutrients, 11(2), 470.
