What Is Low Energy Availability and Why It Matters for Endurance Athletes?
Dec 09, 2024When you’re deep into endurance training, it’s easy to overlook some of the finer details of fuelling yourself right. Next thing you know, you’re constantly tired, your performance has plateaued, and you’re too embarrassed to ask for advice.
Don’t worry—that’s precisely why I’m here.
In this post, I’ll break down low energy availability (LEA) and explain why understanding it is crucial to avoid burnout, optimise your training, and achieve peak performance in your endurance sport.
What is low energy availability (LEA)?
At its most basic, low energy availability happens when the energy you consume through food isn’t enough to support both your training and the essential functions of your body.
In other words, your body doesn’t have enough fuel left after exercise to power key processes like:
- Hormone regulation
- Muscle repair
- Other core functions like digestion and temperature regulation
For athletes, LEA often sneaks in when training volume increases, eating habits don’t keep up, or restrictive dieting practices get in the way.
How does it affect you?
Chronic low energy availability can lead to Relative Energy Deficiency in Sport (RED-S), which impacts both physical and mental performance. Symptoms include:
- Reduced bone density and higher injury risk
- Hormonal imbalances
- Difficulty concentrating, mood swings, and loss of motivation
How energy availability is calculated
Energy availability (EA) is calculated as:
Energy Availability (EA) = (Energy Intake - Exercise Energy Expenditure) / Fat-Free Mass (FFM)
Here’s what each term means:
- Energy Intake (EI): Total calories consumed from food and beverages in a day.
- Exercise Energy Expenditure (EEE): Calories burned during intentional exercise.
- Fat-Free Mass (FFM): The body’s lean tissue mass, measured in kilograms (kg), excluding fat mass.
Curious to find out your energy availability? Use this calculator to see how your energy intake matches your training demands.
Energy Availability Calculator
What do these numbers mean?
- An energy availability below 30 kcal/kg FFM per day is considered low energy availability.
- Optimal energy availability for health and performance is around 45 kcal/kg FFM per day or more.
If your energy availability consistently falls below 30 kcal/kg FFM, your body enters a state of low energy availability, increasing health risks and reducing performance potential.
Why should endurance athletes care about LEA?
I’m not here to tell you what to care about, but let me share why addressing low energy availability is non-negotiable for endurance athletes:
1. Optimised training performance
When you fuel adequately, your body has the energy to complete high-quality training sessions consistently. Without it, your body doesn’t have the resources it needs to hit key intensity levels or sustain efforts for as long as you need to.
2. Faster recovery
Without enough energy, your muscles can’t repair and rebuild effectively. This leads to extended soreness, fatigue, and a higher risk of overuse injuries.
3. Better long-term health
Chronic LEA can cause hormonal imbalances, bone loss, and weakened immunity. Addressing it isn’t just about this race season—it’s about staying in the sport you love for years to come.
4. Improved mental focus
LEA isn’t just physical. It can lead to mental fatigue, difficulty concentrating, and increased anxiety—things no athlete needs when preparing for key events.
Low energy availability in context
Let’s bring this to life with a real-world scenario (one that I’ve seen many times).
Imagine training for an ultra-marathon. You’re clocking 10+ hours of running a week. You head straight to work right after training, and your first meal for the day is not until lunchtime. By the time you get home, you’re exhausted, and all you can think of doing is hitting the pillow with nothing but a salad in your stomach.
What Happens Next?
You might notice:
- Poor recovery and persistent soreness
- Sleep issues or decreased energy
- A drop in performance metrics like pace or heart rate variability
Over time, you may experience menstrual irregularities (for female athletes) or a noticeable loss of libido (for both genders). These are signs that your body is running on empty, even if you’re still showing up for training.
Client Success Story
Let me tell you about Sophie, one of my clients who was struggling with recurring injuries and constant fatigue. Despite her dedication to training, she couldn’t figure out why her performance was declining.
After analysing her fuelling strategy, we discovered she was in a state of low energy availability. Being a fly-in, fly-out (FIFO) worker, Sophie prioritised training during whatever time she had available and struggled to fuel her body at key times during the day.
Sophie completely turned things around by being strategic about her fuelling and prioritising energy-dense options throughout the day. Implementing a training nutrition strategy that supported quality training, optimal energy and proper recovery became a game-changer as well.
The result? Sophie is now crushing her training sessions, recovering faster than ever, and feeling more energised throughout the day.
3 tips to avoid low energy availability
Raise your hand if you’ve ever felt unsure about how to eat enough to meet your training needs. It’s okay—we’ve all been there. Here are some practical steps to get you on track:
1. Implement a training nutrition strategy
Fuelling at the correct times can make all the difference in your performance and recovery. Before your workout, especially longer sessions, focus on easily digestible carbohydrates to provide quick energy and set yourself up for success.
Post-training, prioritise a mix of carbohydrates and protein within 30–60 minutes. This combination replenishes glycogen stores and kick-starts muscle repair, helping you recover faster and return stronger for your next session. It’s a simple but powerful way to maximise your training results.
2. Track more than calories
Numbers on a food log only tell part of the story. It’s just as important to pay attention to how your body feels—your energy levels, mood, and recovery times provide invaluable insight into how well you’re fuelling.
Focus on nutrient-dense meals that support your training demands, but don’t shy away from quick, easily digestible carbs when needed. Listening to your body helps you fine-tune your nutrition, ensuring you’re meeting both your energy needs and overall performance goals.
3. Work with an expert
Navigating energy availability can feel overwhelming, especially when balancing training, recovery, and daily life. Working with an expert takes the guesswork out of the equation. A professional can help you tailor a nutrition plan that aligns with your training demands, lifestyle, and personal goals, ensuring you’re fuelling for peak performance without overcomplicating things.
As someone who has helped countless endurance athletes optimise their nutrition, I understand your challenges and how to overcome them. Whether it’s refining your fuelling strategy or addressing specific concerns like fatigue or performance plateaus, I’m here to guide you every step of the way.
Key takeaways
Let’s wrap this up:
- Low energy availability (LEA) happens when you don’t fuel enough for both training and daily life.
- It can lead to poor performance, longer recovery, and serious health risks.
- Addressing LEA with smart fuelling strategies can keep you strong, sharp, and ready to perform at your best.
At IntensEATfit, I make it my mission to help endurance athletes fuel their training with confidence, optimising performance while safeguarding their long-term health.
If you’re ready to take the guesswork out of your nutrition, check out my Fuel to Thrive Academy, where you’ll gain the guidance, tools and support to fuel your endurance success.
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