The Effects of Relative Energy Deficiency in Sport (RED-S) on Endocrine, Bone, and Metabolic Health and Athletic Performance: A Narrative Review

Authors

DOI:

https://doi.org/10.12775/QS.2026.54.70460

Keywords

Relative Energy Deficiency in Sport, RED-S, low energy availability, athletes, bone health, endocrine function, metabolic adaptations, injury risk, athletic performance

Abstract

Background: Relative Energy Deficiency in Sport (RED-S) is a syndrome caused by low energy availability that impairs multiple aspects of athletes’ health and performance. It affects both female and male athletes and may lead to endocrine, bone, and metabolic disturbances, as well as impaired recovery and increased injury risk.
Aim: To review the effects of Relative Energy Deficiency in Sport (RED-S) on athletes’ endocrine, bone, and metabolic health, as well as on athletic performance and injury risk.
Material and methods: A narrative review of studies published between 2016 and 2025 was conducted using PubMed, Scopus, and Web of Science to evaluate the effects of LEA and RED-S on endocrine, bone, metabolic, and performance-related outcomes in athletes
Results: RED-S was consistently associated with endocrine and metabolic disturbances, impaired bone health, and a higher risk of bone stress injuries. Evidence for adverse effects on recovery, training adaptation, and performance was also identified, although these findings were more heterogeneous.
Conclusions: RED-S is a multisystem condition that can compromise athletes’ endocrine, bone, and metabolic health, with the strongest evidence relating to skeletal health and bone stress injury risk. Early recognition and correction of low energy availability are essential to protect both health and athletic performance.

References

1. Mountjoy M, Ackerman KE, Bailey DM, et al. 2023 International Olympic Committee’s (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs). Br J Sports Med. 2023;57(17):1073-1097. doi:http://doi.org/10.1136/bjsports-2023-106994

2. Gallant TL, Ong LF, Wong L, et al. Low Energy Availability and Relative Energy Deficiency in Sport: A systematic review and meta-analysis. Sports Med. 2025;55(2):325-339. doi:http://doi.org/10.1007/s40279-024-02130-0

3. Melin AK, Areta JL, Heikura IA, Stellingwerff T, Torstveit MK, Hackney AC. Direct and indirect impact of low energy availability on sports performance. Scand J Med Sci Sports. 2024;34(1):e14327. doi:http://doi.org/10.1111/sms.14327

4. Burke LM, Ackerman KE, Heikura IA, et al. Mapping the complexities of Relative Energy Deficiency in Sport (REDs): Development of a physiological model by a subgroup of the International Olympic Committee (IOC) Consensus on REDs. Br J Sports Med. 2023;57(17):1098-1108. doi:http://doi.org/10.1136/bjsports-2023-107335

5. Stellingwerff T, Mountjoy M, McCluskey WT, et al. Review of the scientific rationale, development and validation of the International Olympic Committee Relative Energy Deficiency in Sport Clinical Assessment Tool: V.2 (IOC REDs CAT2). Br J Sports Med. 2023;57(17):1109-1118. doi:http://doi.org/10.1136/bjsports-2023-106914

6. International Olympic Committee Relative Energy Deficiency in Sport Clinical Assessment Tool 2 (IOC REDs CAT2). Br J Sports Med. 2023;57(17):1068-1072. doi:http://doi.org/10.1136/bjsports-2023-107549

7. Angelidi AM, Stefanakis K, Chou SH, et al. Relative Energy Deficiency in Sport (REDs): Endocrine manifestations, pathophysiology and treatments. Endocr Rev. 2024;45(5):676-708. doi:http://doi.org/10.1210/endrev/bnae011

8. Marzuki MIH, Jamil NA, Mohamad MI, et al. Energy availability and its association with health-related outcomes among national athletes at risk of relative energy deficiency in sports (REDs). BMJ Open Sport Exerc Med. 2024;10(4):e002193. doi:http://doi.org/10.1136/bmjsem-2024-002193

9. Moore EM, Drenowatz C, Williams BT, Brodrick TC, Stodden DF, Torres-McGehee TM. Male endurance athletes: Examination of energy and carbohydrate availability and hormone responses. Nutrients. 2024;16(21):3729. doi:http://doi.org/10.3390/nu16213729

10. Jurov I, Keay N, Spudić D, Rauter S. Inducing low energy availability in trained endurance male athletes results in poorer explosive power. Eur J Appl Physiol. 2022;122(2):503-513. doi:http://doi.org/10.1007/s00421-021-04857-4

11. McGuire A, Warrington G, Walsh A, Byrne T, Doyle L. Measurement of energy availability in highly trained male endurance athletes and examination of its associations with bone health and endocrine function. Eur J Nutr. 2024;63(7):2655-2665. doi:http://doi.org/10.1007/s00394-024-03433-8

12. Silvennoinen JIK, Sipilä PN, Valtonen M, et al. Association between the risk of relative energy deficiency in sport and cholesterol levels in Finnish endurance athletes. BMJ Open Sport Exerc Med. 2025;11(3):e002644. doi:http://doi.org/10.1136/bmjsem-2025-002644

13. Ikegami N, Samukawa M, Sakamaki-Sunaga M, et al. The influence of low energy availability on bone mineral density and trabecular bone microarchitecture of pubescent female athletes: A preliminary study. Int J Environ Res Public Health. 2022;19(9):5580. doi:http://doi.org/10.3390/ijerph19095580

14. Smith EM, Drager K, Groves EM, Gabel L, Boyd SK, Burt LA. New approach to identifying elite winter sport athletes’ risk of relative energy deficiency in sport (REDs). BMJ Open Sport Exerc Med. 2025;11(1):e002320. doi:http://doi.org/10.1136/bmjsem-2024-002320

15. Haines MS, Kaur S, Scarff G, et al. Male runners with lower energy availability have impaired skeletal integrity compared to nonathletes. J Clin Endocrinol Metab. 2023;108(10):e1063-e1075. doi:http://doi.org/10.1210/clinem/dgad215

16. Holtzman B, Popp KL, Tenforde AS, Parziale AL, Taylor KM, Ackerman KE. Low energy availability surrogates associated with lower bone mineral density and bone stress injury site. PM R. 2022;14(5):587-596. doi:http://doi.org/10.1002/pmrj.12821

17. von Brackel FN, Munzinger R, Bartosik M, et al. Impact of Relative Energy Deficiency in Sport (REDs) on bone health in elite athletes: A retrospective analysis. J Cachexia Sarcopenia Muscle. 2025;16(5):e70082. doi:http://doi.org/10.1002/jcsm.70082

18. Lundstrom EA, Williams NI, Allaway HCM, et al. Pre-season energy deficiency predicts poorer performance during a competitive season in collegiate female long-distance runners. Eur J Sport Sci. 2025;25(3):e12261. doi:http://doi.org/10.1002/ejsc.12261

19. Stenqvist TB, Torstveit MK, Faber J, et al. Impact of a 4-week intensified endurance training intervention on markers of Relative Energy Deficiency in Sport (RED-S) and performance among well-trained male cyclists. Front Endocrinol (Lausanne). 2020;11:512365. doi:http://doi.org/10.3389/fendo.2020.512365

20. Ackerman KE, Holtzman B, Cooper KM, et al. Low energy availability surrogates correlate with health and performance consequences of Relative Energy Deficiency in Sport. Br J Sports Med. 2019;53(10):628-633. doi:http://doi.org/10.1136/bjsports-2017-098958

21. Cabre HE, Moore SR, Smith-Ryan AE, Hackney AC. Relative Energy Deficiency in Sport (RED-S): Scientific, clinical, and practical implications for the female athlete. Dtsch Z Sportmed. 2022;73(7):225-234. doi:http://doi.org/10.5960/dzsm.2022.546

22. Marzuki MIH, Mohamad MI, Chai WJ, et al. Prevalence of Relative Energy Deficiency in Sport (RED-S) among national athletes in Malaysia. Nutrients. 2023;15(7):1697. doi:http://doi.org/10.3390/nu15071697

23. Lodge MT, Ward-Ritacco CL, Melanson KJ. Considerations of low carbohydrate availability (LCA) to Relative Energy Deficiency in Sport (RED-S) in female endurance athletes: A narrative review. Nutrients. 2023;15(20):4457. doi:http://doi.org/10.3390/nu15204457

24. Everett S. Optimizing performance nutrition for adolescent athletes: A review of dietary needs, risks, and practical strategies. Nutrients. 2025;17(17):2792. doi:http://doi.org/10.3390/nu17172792

25. Holtzman B, Kelly RK, Saville GH, et al. Low energy availability surrogates are associated with Relative Energy Deficiency in Sport outcomes in male athletes. Br J Sports Med. 2024;59(1):48-55. doi:http://doi.org/10.1136/bjsports-2024-109165

26. Vardardottir B, Gudmundsdottir SL, Tryggvadottir EA, Olafsdottir AS. Patterns of energy availability and carbohydrate intake differentiate between adaptable and problematic low energy availability in female athletes. Front Sports Act Living. 2024;6:1390558. doi:http://doi.org/10.3389/fspor.2024.1390558

27. Meyer A, Haigis D, Klos B, et al. Relative Energy Deficiency in Sport-Multidisciplinary Treatment in Clinical Practice. Nutrients. 2025;17(2):228. doi:http://doi.org/10.3390/nu17020228

28. DeJong Lempke AF, Reece LM, Whitney KE. Nutrition educational interventions for athletes related to low energy availability: A systematic review. PLoS One. 2025;20(2):e0314506. doi:http://doi.org/10.1371/journal.pone.0314506

Quality in Sport

Downloads

Published

2026-04-19

How to Cite

1.
KWITOWSKA, Patrycja, UBYSZ, Eryk, MURASZEWSKI, Łukasz, MURASZEWSKA, Emilia, NIERADKA, Kornelia and KRAKOWIAK, Dominika. The Effects of Relative Energy Deficiency in Sport (RED-S) on Endocrine, Bone, and Metabolic Health and Athletic Performance: A Narrative Review. Quality in Sport. Online. 19 April 2026. Vol. 54, p. 70460. [Accessed 19 April 2026]. DOI 10.12775/QS.2026.54.70460.

Issue

Vol. 54 (2026)

Section

Medical Sciences

License

Copyright (c) 2026 Patrycja Kwitowska, Eryk Ubysz, Łukasz Muraszewski, Emilia Muraszewska, Kornelia Nieradka, Dominika Krakowiak

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Stats

Number of views and downloads: 1
Number of citations: 0