Low Energy Availability in Young Athletes
Low energy availability in young athletes happens when a child or teenager is not taking in enough energy from food and drink to support both their sport and the body’s normal needs such as growth, recovery, hormone balance and general health. Kids Back 2 Sport explains that this can happen either because energy intake drops, or because training volume or intensity increases without enough extra fuelling.
It is an important topic for parents, coaches and young athletes because low energy availability can affect performance, increase fatigue, disrupt hormone health and raise the risk of illness and injury, including bone stress injuries. The PDF also explains that sustained low energy availability may contribute to Relative Energy Deficiency in Sport (RED-S) or dance-related RED-D.
What Is Low Energy Availability?
Low energy availability, often shortened to LEA, describes a mismatch between how much energy a young athlete consumes and how much energy their body uses. After exercise is taken into account, there may not be enough energy left to support the body’s essential functions, including growth, repair, hormone regulation, immunity and performance.
This does not only affect elite athletes. It can affect active children and teenagers across many sports, especially during busy training periods, competition blocks, growth spurts or times of poor recovery. The PDF notes that energy availability sits on a continuum, so some athletes may move in and out of low energy availability depending on their training and lifestyle demands.
Why Low Energy Availability Matters in Growing Athletes
Young athletes are not just exercising bodies. They are also growing and developing, which means their energy needs can be higher than many adults realise. Kids Back 2 Sport explains that adolescents involved in sport often need more energy than their non-athletic peers in order to support wellness, growth and performance.
When the body does not receive enough energy, it may begin to prioritise basic survival over higher-level functions. Our free download compares this to a mobile phone switching into power-saving mode. In that state, hormone function, growth, bone health, muscle growth and recovery may all be affected.
This is one reason why some young athletes seem to train hard but do not get stronger, fitter or more resilient. Poor fuelling and poor recovery can reduce the body’s ability to adapt positively to training.
What Causes Low Energy Availability?
Low energy availability can develop in different ways. According to the Kids Back 2 Sport PDF, the two main routes are:
1. A drop in energy intake – This might happen when a child skips meals, follows a restrictive diet, avoids key food groups or simply does not eat enough for how active they are.
2. An increase in exercise without enough extra fuel – This can happen when training volume or intensity rises, but food intake does not rise with it.
Our free resource also explains that low energy availability may be intentional or unintentional. Intentional LEA may be linked to body image concerns, pressure around performance, weight-category sports or aesthetic sports such as dance and gymnastics. Unintentional LEA may occur in sporty children who are time poor, unaware of their nutritional needs, in a rapid growth spurt, fussy eaters, vegan, or affected by digestive issues or food intolerances.
Signs and Symptoms of Low Energy Availability in Young Athletes
Low energy availability does not always look the same in every child, but the PDF highlights several warning signs that may suggest the body is struggling to cope. These include fatigue, poor sleep quality, low motivation, recurrent sore throats or infections, niggling injuries, a drop in performance, stress, irritability and, in girls who have started menstruating, irregular or stopped periods.
Other possible effects mentioned in the PDF include poor healing time, trouble building muscle, digestive dysfunction, bone stress injuries and wider impacts across multiple body systems.
Not every young athlete with these symptoms has RED-S or low energy availability, but persistent symptoms should not be ignored. Kids Back 2 Sport advises seeking medical assessment when symptoms continue or hormonal patterns change.
Low Energy Availability, Hormones and Growth
One of the most important messages in the PDF is that insufficient energy can disrupt hormone health. When the body senses that there is not enough available energy, it may down-regulate processes linked to growth, reproduction, immunity and bone health.
For girls, menstrual regularity can be an important sign of hormonal health. The PDF states that if periods become irregular, stop after previously starting, or have not begun by age 15, medical review is recommended to investigate the cause.
For boys who have gone through puberty, low testosterone linked to under-fuelling may contribute to reduced motivation, fatigue and other changes. The broader point is that conversations around hormone health need to be normalised in adolescent sport.
Low Energy Availability and Bone Health
Bone health is a major concern in growing athletes. The PDF explains that healthy bone is constantly remodelling, but inadequate energy availability can slow bone turnover, reduce bone mineral density and increase the risk of bone stress injuries and fractures.
That matters even more in children and teenagers because adolescence is a key period for building peak bone mass. When low energy availability combines with high training loads, poor recovery or rapid growth, injury risk may rise further. Related Kids Back 2 Sport content on shin splints also connects bone stress injury risk with inadequate nutrition and low energy availability.
What Is RED-S?
RED-S stands for Relative Energy Deficiency in Sport. The PDF explains that this term is used to describe the wide-ranging physical and psychological consequences of sustained low energy availability across different body systems and in athletes of different ages and levels.
RED-S may affect performance, bone health, healing, immunity, digestion, mood, the reproductive system and cardiovascular health. The presentation varies from person to person, which is why proper assessment matters.
How Low Energy Availability Is Managed
The aim of treatment is to restore healthy energy availability. The PDF explains that this may involve improving fuelling, reducing exercise volume or intensity, introducing more low-intensity days, and planning recovery more effectively.
In some cases, especially when under-fuelling is unintentional, education alone can help young athletes and families make changes quickly. In more complex cases involving disordered eating, eating disorders or significant psychological drivers, support from appropriately trained health professionals may be needed.
In our free resource it also notes that recovery times vary. Energy status may improve relatively quickly, but hormonal recovery can take months and bone mineral density may take a year or longer to recover, meaning return to sport should be planned carefully with clinical guidance.
How Parents and Coaches Can Help
Young athletes need a balanced diet with adequate carbohydrates, fats and protein, especially at breakfast and around training. Food should not be demonised or treated as something that must be earned through exercise.
Adults around the child should also pay attention to periods of high demand, such as growth spurts, competitions, double training days and busy school weeks. These are times when extra fuelling and better recovery planning may be needed. The aim is to create a positive environment where athletes understand that good fuelling and recovery support both health and performance.
When to Seek Professional Help
If a young athlete has ongoing fatigue, repeated injuries, poor recovery, recurrent illness, a drop in performance, menstrual changes or other concerning symptoms, it is sensible to seek professional advice early. The PDF recommends medical input, and mentions sports medicine doctors, sports nutritionists and MSK physiotherapists as appropriate professionals who may help assess the next steps.
Frequently Asked Questions About Low Energy Availability in Young Athletes
What is low energy availability in sport?
Low energy availability means a young athlete is not taking in enough energy to support both exercise and the body’s normal needs such as growth, hormone function, bone health, recovery and immunity.
Can children and teenagers get RED-S?
Yes. The Kids Back 2 Sport PDF explains that sustained low energy availability can lead to RED-S, which can affect male and female athletes of different ages and levels, with consequences across multiple body systems.
What are the warning signs of low energy availability?
Possible signs include fatigue, poor sleep, recurrent sore throats or infections, niggling injuries, low motivation, a drop in performance, irritability and menstrual changes in girls.
Does low energy availability affect bone health?
Yes. The PDF states that inadequate energy availability can slow bone turnover, lower bone mineral density and increase the risk of bone stress injuries and fractures.
Is low energy availability always caused by an eating disorder?
No. Kids Back 2 Sport makes clear that low energy availability is not always caused by disordered eating or an eating disorder. It can also happen unintentionally when a child is very active, in a growth spurt, skipping meals, time poor, or not aware of how much fuel they need.
What should parents do if they are worried?
If symptoms are persistent, or if there are concerns about health, periods, recovery, repeated injury or eating habits, it is best to seek assessment from an appropriate healthcare professional.
Concerned About Your Child’s Energy Levels, Recovery or Recurrent Injuries?
Reviewed by Kids Back 2 Sport
Based on educational material by Angela Jackson and Lucy Gillbanks on low energy availability, RED-S and young athlete health.
Reviewed by Kids Back 2 Sport
Based on educational material by Angela Jackson and Lucy Gillbanks on low energy availability, RED-S and young athlete health.
This information is for patients who already have a diagnosis from a qualified health practitioner. The material on this website is designed to support, not replace, the relationship that exists between you and your qualified health professional. If your symptoms are not settling, please do ask for help from one of the practitioners listed on the Kids Back 2 Sport directory or a health professional with experience in children’s conditions.