May 26, 2026 //
Rob Anderson //
Gym News //
6 min read
Many parents of youth athletes assume that if their child is eating three meals a day, they are getting enough fuel. But when a child is training multiple times a week, playing matches on the weekend, and going through a growth spurt, their energy demands skyrocket.
When the energy going in does not match the energy going out, they enter a state called Low Energy Availability (LEA).
Low Energy Availability affects youth athletes of all sports and all levels. If they do not eat enough for what they do, they will eventually break down with injury or illness.
Low energy availability: The Body In Power Saving Mode
Think of your childs body like a smartphone on 10% battery. When energy is too low, the body goes into power saving mode. It shuts down non-essential systems just to survive.
For a youth athlete, those “non-essential” systems include growth, hormone production, bone health, and immunity.
The result is a frustrating cycle. They train hard, but because they lack the fuel to recover and adapt, they actually get weaker, slower, and more injury prone. You train, but without getting fitter and stronger.
Who Is Most At Risk of Low Energy Availability?
Low Energy Availability can be intentional or unintentional.
Unintentional Low Energy Availability is incredibly common. This is the teenager who skips breakfast, trains every day, and simply does not realise how much fuel they actually need to support their activity level. They are not trying to lose weight; they are just under-fuelling by accident.
Intentional Low Energy Availability happens when an athlete deliberately cuts calories or carbohydrates. Often, this is based on the outdated and dangerous advice that “lighter is faster.”
The Warning Signs of Low energy availability:
As a parent or coach, you need to be able to spot the red flags. Look out for these warning signs:
Physical Signs
Niggly injuries that will not heal.
Recurrent sore throats and viruses.
Stress fractures.
Extreme, chronic fatigue.
Behavioural Signs
A sudden drop in performance despite hard training.
Loss of motivation for their sport.
Being grumpy, stressed, and exhausted all the time.
The Impact on Girls and Boys
Low Energy Availability affects both male and female athletes, but the hormonal signals look different.
The Impact on Girls
Regular periods are a barometer of healthy hormones. If they become irregular or stop completely, this is a major red flag for Low Energy Availability. Irregular or absent periods drastically increase the risk of bone stress injuries and long-term bone health problems.
The Impact on Boys
In male athletes, Low Energy Availability causes a drop in testosterone. This leads to low mood, a loss of motivational drive, and chronic exhaustion. They are not just being grumpy teenagers. They may simply not be eating enough for the activity they do.
The Bone Health Danger
One of the most severe consequences of Low Energy Availability is the impact on bone health.
When energy is inadequate, bone turnover slows down. Less new bone is formed, and overall bone mineral density drops. This creates a much greater risk of bone stress injuries and fractures, even in young athletes who appear completely healthy on the outside.
Because adolescence is the critical window for building lifelong bone density, the damage done by Low Energy Availability during these years can have permanent consequences.
When Low Energy Availability Becomes “REDs”
If Low Energy Availability is ignored and prolonged, it develops into a clinical syndrome known as REDs (Relative Energy Deficiency in Sport).
REDs occurs when sustained low energy affects every single body system. It impacts digestion, cardiovascular health, immunity, protein synthesis, and mental wellbeing.
It is important to note that REDs can only be diagnosed by a doctor once other medical conditions have been ruled out, as many of the symptoms mimic other illnesses. If you suspect your child is suffering from REDs, you must always seek medical advice.
How To Fix The Energy Balance
For athletes dealing with unintentional Low Energy Availability, the fix is often straightforward: they need to eat more.
The Golden Rule
Never train on an empty tank. Athletes must eat more on heavy training and match days to meet the increased demand. Do not borrow the energy needed for basic survival and use it for sport.
Prioritise Recovery
Schedule proper recovery days where training stops. However, on these rest days, athletes should eat as though they are still training. This helps to restore the energy balance and allows the body to repair and adapt.
If you are concerned about your childs training load and whether they are at risk of Low Energy Availability, get our free Peak Performance Profile tool.
The Bone Health Danger One of the most severe consequences of LEA is the impact on bone health. When energy is inadequate, bone turnover slows down. Less new bone is formed, and overall bone mineral density drops. This creates a much greater risk of bone stress injuries and fractures, even in young athletes who appear completely healthy on the outside. Because adolescence is the critical window for building lifelong bone density, the damage done by LEA during these years can have permanent consequences. When LEA Becomes REDs If Low Energy Availability is ignored and prolonged, it develops into a clinical syndrome known as REDs (Relative Energy Deficiency in Sport). REDs occurs when sustained low energy affects every single body system. It impacts digestion, cardiovascular health, immunity, protein synthesis, and mental wellbeing. It is important to note that REDs can only be diagnosed by a doctor once other medical conditions have been ruled out, as many of the symptoms mimic other illnesses. If you suspect your child is suffering from REDs, you must always seek medical advice. How To Fix The Energy Balance For athletes dealing with unintentional LEA, the fix is often straightforward: they need to eat more. The Golden Rule Never train on an empty tank. Athletes must eat more on heavy training and match days to meet the increased demand. Do not borrow the energy needed for basic survival and use it for sport. Prioritise Recovery Schedule proper recovery days where training stops. However, on these rest days, athletes should eat as though they are still training. This helps to restore the energy balance and allows the body to repair and adapt.
If you are concerned about your child’s training load and whether they are at risk of LEA, comment PPP on our latest Instagram post to get our free Peak Performance Profile tool. Sources: Mountjoy et al. IOC Consensus on REDs, BJSM 2023 | Jackson & Lawton, Kids Back 2 Sport 2026
