.png)
.png)
.png)
.png)
_2026122-125305.png)
_2026122-125305.png)
_2026122-125305.png)
_2026122-125305.png)
_2026122-125305.png)
Flat sessions, persistent fatigue and slow recovery are not always signs that your training needs to change. They may be signals that your energy intake is not keeping pace with the demands you are placing on your body.
- Understanding what low energy availability means.
- Recognising common performance and recovery warning signs.
- Matching overall energy and carbohydrate intake to training demand.
Before You Question Your Fitness, Question Your Fuel
You are training consistently, you are showing up, you are putting the work in. But something is off. The sessions feel harder than they should, the reps are not landing, the energy is not there and you have a few niggles that will not shift. Before you question your fitness, question your fuel.
That running on empty feeling is not great, is it? But it can quickly become the norm without you even realising. Falling behind in sessions, heavy legs, muscle soreness lasting all week and no clear explanation for any of it. Your first thought is that it is a training problem. But what if I told you it is a nutrition signal? Here is how to recognise what your body is actually trying to tell you.
What Low Energy Availability Actually Is
Low energy availability is not about being unfit, undertrained, or lacking motivation. It is about a mismatch between the energy going in and the energy going out — and your body has very clear ways of letting you know.
Energy availability is the amount of dietary energy left over for normal bodily functions after the cost of exercise has been accounted for. When that number drops too low, the body starts making decisions about where to direct what little energy it has. Symptoms such as an irregular or missing menstrual cycle, frequent illness, injuries and niggles, low mood, poor sleep, and poor adaptation to training begin to surface. Not all at once, but they start to stack up.
And this does not only happen to athletes who intentionally under-fuel. It can happen to athletes who are eating well but simply not matching their intake to their training output. I call it accidental under-fuelling.
Two of the most common examples I see in elite sport are during pre-season, when training load is high and athletes are consuming the same calories regardless of the daily demand, and athletes eating what they consider healthy but massively under-consuming calories, particularly carbohydrates. Both can lead to low energy availability if they are not spotted early enough.
Spot the Signs
Your body will always tell you when something is wrong. The problem is most athletes are not listening, or they are putting the signs down to something else entirely.
Here are some of the most common ones to look out for.
- Flat sessions and missed reps. The weights that felt fine last week suddenly feel impossible, not because fitness has dropped but because the muscles do not have the fuel to perform and have not recovered from the previous session.
- Persistent fatigue. Tiredness that sleep does not fix. The heaviness that follows you into sessions you should feel fresh for, still feeling lethargic after a rest day, feeling like you could nap at any point in the day.
- Getting ill more than usual. The immune system is one of the first things the body deprioritises under energy restriction. Picking up every cold going is a common early sign and points to weakened immunity, often driven by high physical stress, suboptimal recovery, and vitamin and mineral deficiencies.
- Brain fog. Concentration dips, decision-making in sport suffers, and the mental sharpness athletes rely on starts to fade.
- Slow recovery. DOMS lasting longer than usual, sessions taking more out of you than they put back in, and that consistent underlying fatigue that never quite clears.
- Irregular or missing menstrual cycle. For female athletes this is one of the most significant red flags. The menstrual cycle is a vital sign and when energy availability drops, it is one of the first things the body switches off to conserve resources. Keep an eye on it.
Ask yourself honestly whether any of the above resonates. If it does, it is worth making a note and keeping a log over the coming weeks.
The Solution — More Food, Smarter Fuelling
The fix is not complicated. It rarely is. More calories from good food and fluids, a closer look at training load, and letting go of the fear around carbohydrates on your hardest days.
Start by increasing overall calorie intake from food and fluids to match your training demand. This does not mean tracking obsessively — it means becoming more aware of what your training week looks like and which days genuinely need more fuel.
Second, take a look at training load. Sometimes the mismatch is not just about eating more but about the volume of training increasing without the nutrition following it.
And third, embrace carbohydrates on hard training days. This links back to fuelling for strength versus high intensity and reinforces the point that carbohydrates are a performance tool, not something to be afraid of.
Fuel the Output You Are Asking For
Eating more is not a step backwards. It is the thing that allows everything else you are doing to actually work. Start seeing your body as an engine that needs the right fuel to deliver the output you are asking of it.
The athletes who address low energy availability do not just feel better — they perform better, sleep better, recover better, and stay healthier across the full year. Underfuelling is not discipline. It is a barrier to every performance goal you are working towards.
The Bottom Line
- Low energy availability is a mismatch between energy in and energy out, not a fitness problem.
- Your body will ration energy when intake is too low and performance is the first thing it cuts.
- Flat sessions, persistent fatigue, brain fog and a missing cycle are all signs worth taking seriously.
- Getting ill more than usual and slow recovery are early red flags that nutrition needs attention.
- The fix is more food, smarter fuelling around sessions and letting go of the fear of carbohydrates.
- Underfuelling is not discipline, it is a barrier to every performance goal you are working towards.
Quality Assurance
Quality assurance is an important consideration when choosing sports nutrition products. Athletes should look for products that are manufactured to high standards and, where relevant, tested through recognised third-party programmes such as the Informed Sport Program.
