Under-fuelling is one of the biggest risks to female athlete health and performance. Here's what to understand.
Under-fuelling is one of the biggest risks to female athlete health and performance. Here's what to understand.
Of all the topics in female athlete nutrition, energy availability is the most important and the most misunderstood. It sits beneath performance, health and long-term wellbeing, and getting it wrong, usually through inadvertent under-fuelling, is one of the biggest risks a female athlete faces. Yet it is rarely discussed as clearly as it should be.
Understanding energy availability empowers female athletes to fuel in a way that supports both their performance and their health. Here is what it means and why it matters so much.
Energy availability is the amount of energy left to support your body's essential functions after the energy cost of your training has been met. If you take in enough to cover both your training and your body's basic needs, your energy availability is adequate. If you consistently take in too little, it is not.
The concept matters because your body prioritises fuelling exercise, so when total intake is too low, it is your essential functions, not your training, that lose out. This is why chronic under-fuelling has consequences that reach well beyond feeling tired.
Consistently low energy availability can disrupt hormonal function, affect bone health, impair recovery, weaken immune function and ultimately harm performance. In female athletes it is associated with disruption to the menstrual cycle, which is an important warning sign that energy intake is inadequate relative to output.
These effects can develop gradually and are easy to miss until they become significant. This is what makes energy availability so important to understand proactively, rather than only recognising a problem once it has taken hold.
Low energy availability is often inadvertent rather than deliberate. It can arise simply from increasing training without increasing intake to match, from a busy life crowding out adequate eating, or from underestimating how much energy training actually costs. It does not require any intention to restrict.
This is why awareness matters so much. Many female athletes running at a chronic deficit have no idea they are doing so, because the gap between what they burn and what they eat has crept in gradually and unnoticed.
The solution is to ensure your total energy intake genuinely matches your training load, which for a hard-training athlete means eating more than many expect. This includes adequate carbohydrate to fuel your training and support availability, alongside protein and overall energy.
Fuelling around your sessions, before, during longer efforts, and after, is part of this, both for performance and to help meet your overall energy needs. Adequate fuelling is not indulgent; it is what allows your body to function and adapt.
Warning signs that energy availability may be too low include menstrual cycle disruption, persistent fatigue, frequent illness or injury, and stalling performance despite training hard. Any of these warrants attention and, where appropriate, professional guidance from a qualified practitioner.
Taking these signs seriously rather than pushing through them is important, because addressing low energy availability early is far easier than dealing with its longer-term consequences. This is a case where listening to your body genuinely matters.
Energy availability, having enough energy left for your body's essential functions after training, is foundational to female athlete health and performance. Under-fuelling is often inadvertent, its effects develop gradually, and awareness is the key protection.
For female athletes, fuelling adequately to match your training load is not just about performing better; it is about protecting your health for the long term. It is the most important nutritional principle there is.