Authors’ 2015 additions to the IOCconsensus statement: Relative EnergyDeficiency in Sport (RED-S)Margo Mountjoy,1 Jorunn Sundgot-Borgen,2 Louise Burke,3

Susan Carter,4 Naama Constantini,5 Constance Lebrun,6

Nanna Meyer,7 Roberta Sherman,8 Kathrin Steffen,2,9

Richard Budgett,9 Arne Ljungqvist9

In April 2014, the International OlympicCommittee (IOC) published a ConsensusStatement in this journal entitled “Beyondthe Female Athlete Triad: Relative EnergyDeficiency in Sport (RED-S)”.1 In reference tothat Consensus Statement, Professor MaryJane De Souza and colleagues published aneditorial ( July 2014).2 The editorial belowexpands on the original ConsensusStatement and comments on the 2014Editorial by Professor Mary Jane De Souzaand colleagues.

RELATIVE ENERGY DEFICIENCY INSPORT (RED-S)Albert Einstein said: “The important thingis to never stop questioning.” A group of 11IOC authors have called attention, as othersin the past,3 4 to a problem that is widerand more complex than originally identi-fied when the term ‘Female Athlete Triad’(Triad or FAT) was first coined in 1992. Justas knowledge evolves, so too should ideasand constructs on how to address it.

Given the evolution of science since1992, and to more accurately describe theclinical syndrome originally known as theFemale Athlete Triad, the IOC introduceda more comprehensive, broader term:Relative Energy Deficiency in Sport.

The syndrome of RED-S refers toimpaired physiological functioningcaused by relative energy deficiency, andincludes but is not limited to impair-ments of metabolic rate, menstrual func-tion, bone health, immunity, proteinsynthesis, and cardiovascular health.

Our April 2014 Consensus statementidentifies the aetiological factor underpin-ning the syndrome as:

an energy deficiency relative to the balancebetween dietary energy intake and theenergy expenditure required to supporthomeostasis, health and the activities ofdaily living, growth and sporting activities.

We reaffirm the principle that the IOCConsensus Statement highlights aboutenergy deficiency/low energy availabilityamong exercising people. De Souza andcolleagues’ editorial criticises the use of theword ‘balance,’ suggesting that the IOCauthors have confused the terms energyavailability and energy balance. We used theterm ‘balance’ in the context of comparingtwo items which are not necessarily equal.To clarify, the underlying aetiology ofRED-S is the same as that which underpinsthe Triad—low energy availability. Thereason we chose the term RED-S—RelativeEnergy Deficiency in Sport—is to recognisethat low energy availability can occur in thepresence of energy balance.To clarify:

The cause of the Relative EnergyDeficiency in Sport is the scenariotermed ‘low energy availability’, wherean individual’s dietary energy intake isinsufficient to support the energyexpenditure required for health, func-tion and daily living, once the costs ofexercise and sporting activities are takeninto account.

LIMITATIONS OF THE TERMINOLOGY‘FEMALE ATHLETE TRIAD’—WHY IT’SOVERDUE FOR A ‘REBRAND’The understanding of the Triad hasstrengthened over the past three decadesbecause people were brave enough to

stand up and describe a problem withsome apparent features that neededurgent and focused investigation. Parts ofthe original model have been updatedover time with new knowledge, and thesports medicine and exercise science com-munity has embraced this evolution ratherthan insisting that the Triad be invalidatedbecause the details have changed. In fact,

Relative Energy Deficiency in Sport

Key Definitions:Energy balance:5 6 Energy Balance is theamount of dietary energy added to orlost from the body’s energy stores afterall of the body’s physiological systemshave completed their work for the day.(EB=Energy intake—Total energyexpenditure)Energy deficit: Energy deficit is thediscrepancy in energy balance whendietary energy intake is less than totalenergy expenditure, such that energy islost from the body’s energy stores and/orcompensatory mechanisms take place toreduce total energy expenditure.Energy availability:5 6 Energy availabilityis the amount of dietary energyremaining to support remainingmetabolic systems in the body after theenergy cost for a particular system hasbeen removed: In the case of athletes,energy availability is the amount ofenergy remaining to support all otherbody functions after the energyexpended in exercise and sportingactivities is removed from energy intake.(EA=Energy intake—Energy expended inexercise)Low energy availability:5 6 Low energyavailability occurs when an individual’sdietary energy intake is insufficient tosupport the energy expenditure requiredfor health, function and daily living, oncethe cost of exercise and sportingactivities is taken into account.Relative Energy deficiency: Relativeenergy deficiency connotes that lowenergy availability can occur even in thescenario where energy intake and totalenergy expenditure are balanced(ie, there is no overall energy deficit).Relative Energy Deficiency in Sport:1

The syndrome of RED-S refers toimpaired physiological functioningcaused by relative energy deficiency, andincludes but is not limited toimpairments of metabolic rate, menstrualfunction, bone health, immunity, proteinsynthesis and cardiovascular health.

1Department of Family Medicine, Michael G. DeGrooteSchool of Medicine, McMaster University, Hamilton,Ontario, Canada; 2Department of Sports Medicine,The Norwegian School of Sport Sciences, Oslo, Norway;3Department of Sports Nutrition, Australian Institute ofSport, Belconnen, Australia; 4University of NorthernColorado, University of Colorado Medical School,Colorado, USA; 5Orthopedic Department, Hadassah-Hebrew University Medical Center, Jerusalem, Israel;6Department of Family Medicine, Faculty of Medicine &Dentistry, Glen Sather Sports Medicine Clinic, Universityof Alberta, Edmonton, Alberta, Canada; 7HealthSciences Department, University of Colorado, ColoradoSprings, Colorado, USA; 8The Victory Program atMcCallum Place, St. Louis, Missouri, USA; 9IOC Medicaland Scientific Department, Lausanne, Switzerland

Correspondence to Margo Mountjoy, Department ofFamily Medicine, Michael G. DeGroote School ofMedicine, McMaster University, Hamilton, Ontario,Canada; mmsportdoc@mcmaster.ca

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if one applied a pedantic critique of theTriad, many of the criticisms levelled atRED-S could also apply to it:A. Female: scientific publications clearly

demonstrate that relative energy defi-ciency also affects men.7–24

B. Athlete: by identifying the ‘athlete’ inthe title, the Female Athlete Triad failsto account for recreational exercisersand dancers who would not identifythemselves as athletes but who candevelop relative energy deficiency.

C. Triad:1. The literature describes many more

than two negative outcomes of lowenergy availability, so it either isnot really a triad or it ignores/undervalues these other issues.

2. According to many studies, ath-letes have one or two of the threetraditional components of thetriad, so it is not a true triad.

3. De Souza and colleagues’ editorialstates that it can continue to callthe syndrome a triad because thethree corners (low energy availabil-ity/menstrual dysfunction/poorbone health) are the most seriousparts. However, it is unclear whatcriteria are used to justify thisassessment and why other aspectsof the health/performance impair-ments associated with low energyavailability do not merit toplinerecognition.

4. The term ‘Triad’ does not prioritisethe key element. When the ‘Triad’was first coined, investigators werenot aware that energy deficiencywas the key problem. Subsequently,Anne Loucks and others have pro-vided compelling data on the pre-eminence of energy deficiency asthe causative element. Why confusetrainees, health professionals andathletes by referring to a ‘triad’when the culprit is not osteoporosis,not amenorrhoea (two elements ofthe ‘triad’ as coined in 1992) butenergy deficiency? Hence the rec-ommendation of ‘Relative EnergyDeficiency in Sport (RED-S)’.

D. The Female Athlete Triad acronym(FAT): While researchers and clini-cians involved in the work of FemaleAthlete Triad refer to it as ‘Triad,’many others refer to it as ‘FAT,’ anunfortunate acronym.

E. Female Athlete Triad Model: The presentmodel/diagram and description fail toportray the interrelatedness of all thefactors, the concern about subclinicallevels of presentation, and the concern ifall three issues are not involved. Thus, it

does not accurately describe the com-plexity of the syndrome.

MALE ATHLETES ARE AFFECTED—ITIS IRREFUTABLEAlthough most studies related to RED-Shave been performed on female athletes,there is a growing body of evidence thatthe negative sequelae of low energy avail-ability also occur in male athletes fromleanness-demanding or weight categorysports, and in scenarios of high volumetraining.8 In particular, these male athletesalso have an increased risk of disorderedeating,9–11 disruption of GonadotrophinReleasing Hormone and Luteinizinghormone (GnRH) and LH pulsatility, aswell as lower sex hormone levels,12–18

impaired reproductive function,20 14 21

decreased immunity11 and impaired bonehealth.22–24

It is certainly possible, as hypothesisedin DeSouza and colleagues’ editorial, thatmale athletes have a different set of issues,outcomes and modifying factors involvedin these observations. However, the IOCauthors believe that these health issuesneed attention, rather than being ignoredbecause they seem less defined.The original version of the Triad pro-

posed that clinical outcomes of disorderedeating, amenorrhoea and osteoporosis werealways involved. The subsequent publishedmodel now recognises that this may not bethe case, and that we still need to be con-cerned about female athletes whose energyavailability, menstrual function and/or bonehealth are suboptimal, even if not yet a clin-ically recognised problem. So why are wediscounting problems of male athletesbecause of a hypothesis that they may notbe as ‘serious’ as those of female athletes?Any level of suboptimal body functioncaused by inadequate energy intake is apotential issue worthy of study and needingthe attention of athletes/coaches/profes-sionals. As knowledge grows, the discussionand recommendations for different groupscan evolve.The hypothesis that low energy avail-

ability/energy deficiency is not as import-ant for men because they do not have thesame energetic cost of reproduction todefend also raises questions aboutwhether the Triad is problematic forwomen outside the reproductive age. Dowe stop worrying about premenarchealand postmenopausal women with lowenergy availability? If energy availability islow, it will reduce the capacity for sometype of body function, activity and/or per-formance. Therefore, since energy defi-ciency and eating disorders seem to havemany similar physiological and health

impairing effects in men as they do inwomen, it is time to broaden the conceptto include men as well as women. Indeed,the Olympic Charter, which documentsthe fundamental principles of Olympism,provides clear direction regarding humanrights in sport and, in particular, againstdiscrimination on the basis of gender:

“The practice of sport is a human right.Every individual must have the possibil-ity of practicing sport, without discrim-ination of any kind…..Any form ofdiscrimination with regard to a country,or a person on grounds of race, religion,politics, gender or otherwise is incom-patible with belonging to the OlympicMovement.”25

The Olympic Movement Medical Codegoes even further, underscoring the obli-gation to avoid gender discrimination inthe provision of medical care of athletes:

“Athletes should receive such health careas appropriate to their needs….Servicesshould be continuously available andaccessible to all equitably, withoutdiscrimination.”26

The current IOC leadership has repeat-edly underscored their commitment to theprotection of athlete health (women andmen).27

RED-S HEALTH AND PERFORMANCECONSEQUENCESThere is always a challenge in developinga simple model for handling complex,multifactorial problems. The RED-S con-ceptual models of potential Health andPerformance Consequences of relativeenergy deficiency are designed for simpli-city of understanding the main principleof the underpinning aetiology of RED-S,which is placed in the centre of the ‘huband spoke’ model. The conceptual modelsare also designed to show a plethora ofphysical, psychological and potential per-formance sequelae that develop as a resultof energy deficiency, regardless of theirrelative importance. The chief purpose ofthe models is to serve as a clinical teachingtool for athletes and coaches to demon-strate the numerous health consequencesof relative energy deficiency, as well as theperformance consequences, which are apriority for them.

The RED-S conceptual models are notdesigned to illustrate either the complexinteractions of physiological and psycho-logical factors involved in the process or theinterconnectivity among the functions andmechanisms involved in the syndrome.Indeed, these synergistic and antagonisticprocess mechanisms are also not captured inthe current Triad model.28 As knowledge of

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the interactions of the functional processesof RED-S advances, the IOC ConsensusStatement authors will embrace theexpected evolution of the RED-S conceptualmodels of the Health and PerformanceConsequences (figures 1 and 2).29

RED-S RISK ASSESSMENT ANDRETURN TO PLAY MODELSThe RED-S ‘Red Light—Yellow Light—Green Light’ Risk Assessment and Return

to Play (RTP) models are designed to takea complex clinical assessment and RTPdecision-making process and integratethem into a functional model that issimple to understand by the athlete andthe clinician, as well as relatively easy toimplement in the ‘real world’. The chal-lenge of designing a functional model tobetter manage complex clinical scenariosarises in all areas of medicine. Clinicianswant guiding principles to assist with

medical management and harm minimisa-tion. All models have limitations, but theyare designed with latitude in the interpret-ation of an individual’s situation byexperts, acknowledgement of mitigatingfactors, ongoing monitoring of the indi-vidual, and continual re-evaluation of themodel.

The RED-S ‘Red Light—Yellow Light—Green Light’ Risk Assessment and Returnto Play models were developed with thisflexibility to allow clinicians in the field theability to adapt the model to their particularathlete situation. For example, the specificlength of ‘prolonged period with lowenergy availability’ is not provided in theRED-S model because there are no studiesindicating the time frame an athlete canexperience energy deficit without com-promising health and performance.However, it is the experience and belief ofthe IOC authors that treating clinicians’knowledge of the sport-specific demandsand case-specific parameters, combinedwith their clinical experience, is sufficientfor them to be able to adapt their particularclinical scenario to the RED-S models tofacilitate a safe RTP decision. In fact, themodels presented in the IOC ConsensusStatement for Risk Assessment and RTPhave been developed and implementedfor more than 2 years at the competitivelevel, for all ages and sport disciplinesof athletes at the Norwegian OlympicTraining Center.30 These models havealready been demonstrated to be successfulin practice.

The models were developed to beadaptable for men and women. The endpoints identified as red light ‘high risk’criteria and yellow light ‘caution’ criteriaapply to male and female athletes, exceptfor the two end points related to the men-strual cycle. Since there are many differentmethods to estimate body compositionand the SE of measurements can be high(as high as 5% and higher for commonlyused field methods if not standardised)31

depending on the method and standard-isation used, it is difficult to specify thelower limit of body fat for male andfemale elite athletes, even though thegeneral guidelines recommend >5% bodyfat for men and 10% for women.31

To further support clinicians in the fieldwith the management of RED-S athletes,the IOC authors have developed a RED-SClinical Assessment Tool (RED-S CAT)modelled after the Sport ConcussionAssessment Tool (SCAT-3),32 which iswidely used in clinical practice. Like theoriginal SCAT, the RED-S CAT is a start-ing point to facilitate clinical practice andto encourage further research and

Figure 1 Health Consequences of Relative Energy Deficiency in Sport (RED-S) (*Psychologicalconsequences can either precede RED-S or be the result of RED-S).

Figure 2 Potential Performance Effects of Relative Energy Deficiency in Sport (**Aerobic andanaerobic performance).

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validation; it is expected to evolve overtime as the body of science in the fieldgrows. The RED-S CAT is also publishedin this issue (see page 421).

FUTURE DIRECTIONSThe IOC authors of the ConsensusStatement on RED-S recommend that thesports medicine and sport science commu-nities gain an increased understanding andawareness of the broadened concept ofRED-S. The RED-S conceptual modelsshould be integrated into performancenutrition educational approaches, as theyoffer an opportunity for athletes andcoaches to understand the broad scope ofissues related to suboptimal eating practices.The RED-S CAT should be implementedglobally to facilitate and improve themedical management of male and femaleathletes.

DeSouza and colleagues are correct thatthe body of published research on RED-Sis not yet as robust as that on the Triad.Indeed, most of the Triad research wasdone AFTER the term was coined. It is arecommendation of the IOC authors, aswritten in the IOC Consensus paper, thatthe scientific experts in the field work col-laboratively to further enhance our under-standing of:▸ The aetiology and best treatment of ath-

letes with RED-S, including men andwomen, able-bodied and disabled popu-lations, and individuals of various races.

▸ The design and validation of tools toaccurately measure energy availabilityin the clinical setting.

▸ The validation of screening tools (suchas the RED-S CAT), prevention andtreatment programmes.In summary, it is evident that the term

‘Female Athlete Triad’ is not only inaccur-ate, but also inadequate to describe thesyndrome. As the underlying aetiology islow energy availability, the coining of new,more comprehensive terminology ‘relativeenergy deficiency in sport’ (RED-S) isintroduced by the IOC following a robustreview and debate of the current sciencebase. It is also time to acknowledge andaddress the health and performance of themale athlete who also suffers fromRED-S. It is time for change.

“Progress is not possible without change.”George Bernard Shaw

Contributors MM and JS-B were involved insubstantial contributions to conception and design,drafting and revising the manuscript and the finalversion to be published. LB, SC, NC, CL, NM, RS andKS were involved in the contribution to design, revisingthe manuscript and the final version to be published.

RB and AL were involved in the review of the finalversion to be published.

Competing interests None.

Provenance and peer review Commissioned;externally peer reviewed.

To cite Mountjoy M, Sundgot-Borgen J, Burke L,et al. Br J Sports Med 2015;49:417–420.

Accepted 17 January 2015

▸ http://dx.doi.org/10.1136/bjsports-2014-094559

Br J Sports Med 2015;49:417–420.doi:10.1136/bjsports-2014-094371

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