What if the reason you aren’t hitting your performance goals isn’t your training, but that you aren’t giving your body enough energy to adapt, build and recover?
As athletes, we’re driven by strong internal and external pressures, and we often assume that better performance comes from training harder, pushing through fatigue, or changing how we look. But training is only one part of the equation. Without adequate fuelling and recovery, even the best training programme can stop producing results.
These pressures take many forms: the desire for extreme leanness, physique changes for a specific sport, attempts to improve athletic ability, and very high training volumes. By altering both energy intake and exercise energy expenditure, they can lead to low energy availability and increase the risk of Relative Energy Deficiency in Sport (REDs).
What is REDs?
“A syndrome of impaired physiological and/or psychological functioning experienced by female and male athletes that is caused by exposure to problematic (prolonged and/or severe) LEA. The detrimental outcomes include, but are not limited to, decreases in energy metabolism, reproductive function, musculoskeletal health, immunity, glycogen synthesis and cardiovascular and haematological health, which can all individually and synergistically lead to impaired well-being, increased injury risk and decreased sports performance.”
The International Olympic Committee (IOC) first introduced Relative Energy Deficiency in Sport in 2014 to describe a syndrome, seen in both female and male athletes, in which low energy intake relative to exercise expenditure impairs physiological and psychological functioning. As research in the field grew, the IOC updated its definition in 2023, quoted above.
Causation of REDs?
How low does your energy intake need to be, and for how long, before it becomes problematic? To answer that, it helps to understand the different grades of energy imbalance.
Energy availability is the energy left for your body’s essential functions once exercise has been accounted for. Low energy availability occurs when a mismatch between dietary intake and exercise expenditure leaves the body’s total energy needs unmet. Adaptable low energy availability causes mild, benign effects, with no impact on long-term health and biomarkers that easily return to baseline. Problematic low energy availability, by contrast, is associated with persistent disruption, and with signs and symptoms that affect longer-term health, well-being and performance.
Duration also matters, from short-term (a couple of weeks) to long-term (a year or more). Understanding this progression helps us, as clinicians, treat and prevent the energy mismatch before health and performance decline.
In some cases, athletes experience low energy availability through cycles of intensified training or competition, periodised into annual programming. This is usually adaptable: experienced coaches build in recovery and monitor the athlete’s physical and psychological readiness. It is the extended duration of low energy availability, shifting from adaptable to problematic, that leads to detrimental performance outcomes and REDs.
Although most research has focused on females, males are also affected, with impacts on hormonal health, immune function, bone health, libido and performance. It is sometimes suggested that males can tolerate lower energy availability before these effects appear, but the thresholds for males are much less well defined, and this remains an emerging area of research.
As the body of REDs research has grown, studies consistently show that problematic low energy availability is one of the biggest factors in its development, along with reduced carbohydrate intake. When energy intake falls and energy demands rise, the body prioritises processes essential for immediate survival and trades off functions linked to growth, reproduction and maintenance. When we think about changing body composition, we tend to emphasise protein and cut carbohydrates during periods of calorie restriction, but could this be doing more harm than good?
There is growing interest in how low carbohydrate availability may contribute to the health-related effects of REDs. Compared with a moderate carbohydrate intake, a lower intake has been linked to impaired markers of bone remodelling, immunity and iron status, in some studies even when energy availability appears adequate, though this independent effect is still being established.
Are you at risk of REDs?
Although REDs was first recognised in elite sport because of its high training demands, we are increasingly aware of how much recreational participation has changed. Many recreational athletes now train at high volumes, with performance-focused goals, structured programmes and competitive targets. Fitting these demands around work and life can push energy expenditure up, blurring the line between recreational exerciser and athlete, but without the regular access to sports dietitians, physicians and physiotherapists that elite athletes rely on to monitor training load, nutrition and recovery.
While more participation at every level is positive, the body can struggle to cope with the demands of some modern elite training programmes, particularly in endurance sports where weekly volumes can be very high (in some cases exceeding 30 hours). Risk tends to rise with the duration, magnitude and frequency of training, as very high energy expenditure outstrips intake, one of the major causes of REDs: problematic low energy availability.
This is why education about REDs matters for a more active population, raising awareness of a condition that arises when the energy available to the body cannot meet the demands placed on it. Recreational athletes may unintentionally develop low energy availability by underestimating their energy needs or following misinformation from social media, fitness culture or popular diet trends.
What are the warning signs your body isn’t coping?
REDs can present in many ways, with signs and symptoms developing gradually depending on the severity of low energy availability. Some are noticeable to the individual; others only show up through more comprehensive medical screening and laboratory testing.
Symptoms you might notice include persistent fatigue or low energy, reduced performance or difficulty progressing with training, frequent injuries (particularly bone stress injuries), a change or loss of menstrual cycle (amenorrhoea), low libido, increased hunger or, in some cases, reduced appetite, mood changes (irritability, anxiety, depression), and difficulty recovering between sessions. Less obvious signs, which a healthcare professional can assess, include hormonal changes (reduced sex hormone levels), a lowered resting metabolic rate, altered cholesterol or other blood markers, and evidence of impaired bone health or reduced bone density.
There is currently no single test or symptom that can diagnose REDs, which is why it is important to seek support from a suitable healthcare professional who can assess the bigger clinical picture: not just your symptoms, but your training load, medical and injury history, energy intake and expenditure, relevant blood markers, and imaging for bone health.
In many cases REDs is preventable, and if recognised early it can be reversible. Research and clinical guidelines continue to evolve, improving how we prevent, diagnose and treat it. By educating people about appropriate fuelling, helping them understand their energy needs, and encouraging them to seek support when something doesn’t feel right, we can reduce the risk of poor health and performance outcomes.
How can we help at Remedy?
If you are experiencing persistent fatigue, recurring injuries, changes in your menstrual cycle, declining performance, or you’re concerned that your nutrition may not be supporting your training, seeking professional advice early can make a real difference. These symptoms don’t automatically mean you have REDs, but they shouldn’t be ignored, particularly if they are affecting your health, recovery or ability to perform at your best.
At Remedy, we take a comprehensive, individualised approach. Rather than focusing on a single symptom, we look at the bigger picture: your training history and current load, nutritional habits, injury and medical history, lifestyle demands and performance goals. This helps us identify contributing factors and build a management plan tailored to you.
Where clinically appropriate, we can guide you through further investigations to rule out other conditions and give a clearer picture of your health. This may include referral for imaging, such as bone health assessments, or blood tests to check nutritional status, hormonal function and other biomarkers. If specialist input is needed, we work alongside GPs, sports physicians, dietitians and other professionals to make sure you receive the most appropriate care.
Recovery from REDs is not simply about eating more or training less. It takes an individualised approach that balances adequate nutrition, appropriate training load and recovery around your personal goals, whether you are preparing for your next race, returning from injury, or simply want to feel healthier and perform at your best. Together, we can assess where you are, answer your questions, and create a plan that supports both your long-term health and your performance.
