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Relative Energy Deficiency in Sport, what is it and how does it affect athletes?

As discussed in episode 1 of the Paper to Podium podcast.

Pushing both your mind and body to its limits is often praised and celebrated within sport culture as a recognition of discipline and strength, but where is the line drawn in regard to both mental and physical health? “No pain, no gain”, “No excuses”, this mindset alongside an increasing number of accessible metrics to the everyday athlete and beyond (i.e. sports watches or commercially available scales allowing estimations of body composition), can lead to fixation on our performance, rarely taking a moment to consider the future losses of our present gains. An unhealthy athlete. Is there such a thing? Relative Energy Deficiency in sport, often referred to as RED-S, is a syndrome that can lead to just that. RED-S by definition is impairments in our physiological function due to low energy availability, caused by a caloric deficit(1). Simply put, RED-S is when we are not eating enough to support normal bodily functions alongside the stress of exercise.

Originally, RED-S was referred to as the female athlete triad until 2014 when the International Olympic Committee updated their position statement with the new term RED-S. RED-S can affect an athlete of any level, elite or recreational, both males and females. It can negatively impact almost every system of the body if left untreated. However, despite its potential severity, RED-S often goes under the radar until highlighted by circumstances such as an injury or extreme mental fatigue.

RED-S impact on performance

RED-S manifests in a number of psychological/physiological symptoms where overall lack of energy means our biological process’ can’t keep up. Psychological effects of this include increased irritability, depression, impaired judgement and decreased concentration. Whilst physiological effects can include decreased muscle strength, impaired endurance performance, decreased training response, impaired co-ordination, decreased glycogen stores and an increased injury risk. All of these factors can impact performance in their own way and collectively have the potential to severely impair performance. Signs of RED-S impacting your performance could present themselves as poor recovery between training sessions, digestive issues or recurrent injuries.

If so impactful, how does RED-S go so unnoticed?

Despite its potential to have such adverse effects, RED-S is still only just becoming widely discussed within a majority of sports. In female runners at a marathon event only 7% knew about RED-S with 44% being at high risk(2)! In research looking at the knowledge of coaches, 98.6% were aware of the female athlete triad but only 33% were aware of RED-S(3). Then similar findings have also been witnessed in health professionals with 76% of professionals being aware of the female athlete triad, but only 29% recorded an awareness of RED-S (4). It is clear that more awareness is needed across the board in athletes, coaches and practitioners.

In females specifically, a key indicator of RED-S is the absence of menstruation, also known amenorrhea. Wait, no period? No cramps or headaches? The ability to be able to continue training as normal? Although every female experience of menstruation is different, in a lot of females it is seen as an inconvenience and can be uncomfortable. A lack of menstruation is often ignored by the athlete themselves if they are too focused on performance metrics. Further to this, the lack of menstruation can also be hidden due to contraceptive methods, so the athlete may not even realise they aren’t menstruating anymore. This alongside a cultural inability to discuss menstruation means this major symptom is easily disregarded. As such, the danger of RED-S is largely due to our failure to recognise them.

Warning signs of RED-S

Physiological signs of RED-S can include poor development of muscle mass, low body weight, reduced bone mineral density, prolonged low-calorie intake or injury such as stress fractures. Behavioural signs include disordered eating patterns such as a constant pre-occupation with food, restricting or strict control of food intake. Other behavioural signs can include overtraining and poor sleep patterns. Finally, psychological signs include irrational behaviour, fear of food or weight gain, socially withdrawing themselves or severe anxiety.

Take home messages

– Fuel your training and competition right. At Science in Sport we have a variety of different ways you can fuel your training and recovery.
Listen to your body and start a conversation. Raise awareness of this condition and talk to people if you have any concerns, the first step in helping those with RED-S is educating others about the area.
Performance should not be at a cost of our health. EVER.


Episode 1 of the Paper to Podium podcast explores weight and mind management with Geraint Thomas, Professor Steve Peters and leading Researcher in this field, Dr Trent Stellingwerff. Find out more here.


If you concerned about RED-S or disordered eating in yourself, someone you know or just want to find out more check out these resources.


1. Mountjoy M, Sundgot-Borgen JK, Burke LM, Ackerman KE, Blauwet C, Constantini N, Lebrun C, Lundy B, Melin AK, Meyer NL, Sherman RT, Tenforde AS, Klungland Torstveit M, Budgett R. IOC consensus statement on relative energy deficiency in sport (RED-S): 2018 update. Br J Sports Med. 2018 Jun;52(11):687-697. doi: 10.1136/bjsports-2018-099193. PMID: 29773536.
2. Folscher LL, Grant CC, Fletcher L, Janse van Rensberg DC. Ultra-Marathon Athletes at Risk for the Female Athlete Triad. Sports Med Open. 2015;1(1):29. doi: 10.1186/s40798-015-0027-7. Epub 2015 Sep 9. PMID: 26380807; PMCID: PMC4564455.
3. Kroshus, E.; DeFreese, J.D.; Kerr, Z.Y. Collegiate athletic trainers’ knowledge of the female athlete triad and relative energy deficiency in sport. J. Athl Train. 2018, 53, 51–59.
4. Tenforde AS, Beauchesne AR, Borg-Stein J, Hollander K, McInnis K, Kotler D, Ackerman KE. Awareness and comfort treating the female athlete triad and relative energy deficency in sport among healthcare providers. Dtsch Z Sportmed. 2020; 71: 76-80.

Written By

Dr Emily Jevons - PhD in Exercise Physiology & Nutrition, Clean Sport Advisor

Emily has worked with Science in Sport since 2021. With a PhD in Exercise Physiology & Nutrition, she currently provides nutritional advice for endurance athletes. Emily not only understands the science behind performance nutrition solutions, but also the physiological and psychological demands of sport after competing competitively in swimming and triathlon for a number of years.