Energy Availability: The Foundation of Nutrition

What is Energy Availability?

Energy availability is the foundation of nutrition, especially for active females. But what exactly does energy availability or 'EA', mean?

Simply put EA refers to the amount of energy the available for basic functioning of the body such as maintaining body temperature, repairing internal organs and tissue, supporting cardiac function and respiration. It is the energy that remains after accounting for dietary energy intake and the energy used for training.

When energy expenditure from training exceeds energy intake, we fall into a state of low EA. As a result, the body does not have enough energy left to sustain basic physiological functions outside of exercise, such as proper digestion of food, repair of muscles and maintaining a stable reproductive cycle. Research has shown that females training in a state of low EA experience muscle loss, slower muscle repair and rebuilding, increased cortisol levels, and reduced thyroid hormones in as little as 10 days (Oxfledt et al 2023 DOI:10.1113/JP284967). Another study found that young servicewomen in a state of low EA experienced a reduction in markers related to bone repair and maintenance within just 5 days (Ihle + Loucks, 2004 PMID: 15231009). You may still be able to swim, bike, run, lift weights (at least for a while), but your body doesn’t have enough energy and nutrition left over to keep your organ systems operating at optimal levels.

Are you in a state of low energy availability (LEA)?

There are many reasons female athletes find themselves in a state of low energy availability (LEA). Some are intentional, such as dieting and restricting carbohydrates. Others are unintentional–we are just unaware of how much energy our body needs to function and perform the activities we ask of them. Particularly when we are surrounded by messages promoting '1500-a-day-calorie diets' or 'eat less to lose weight'. And most often, we are not eating in and around training; if you delay food intake after training, your body stays in a catabolic (breakdown) state, which the brain interprets as insufficient energy to support adaptation as well as overall health.

How can you check if you’re dipping into LEA, even if unintentionally? The first step is to estimate your energy requirements based on your body composition and energy expended during exercise. Then compare this to your current energy intake. While I don’t generally advocate rigidly counting calories or tracking macro-nutrients (carbohydrates, fats and protein), it can be beneficial to keep track for a few days to assess the actual energy intake versus what you perceive it to be. You may be surprised by the results!

The next step is to increase your food intake around your training sessions, and then across the day. Pay attention to how you feel and perform when you’re meeting your energy needs. Again, you may be surprised. So many people feel better and reach their full performance potential once they finally meet their energy needs. A useful and simple to use app is Chronometer. It uses nutritional data which is verified and I find it to be more accurate than other food tracking apps.

It's important to note that calculating your energy needs, or tracking your energy intake, is not an exact science and this will change over time. That's why I encourage my clients to also be aware of other factors such as their mood, levels of tiredness, motivation and quality of sleep. By considering these aspects, we can work together to adjust eating patterns and energy intake based on how your body responds. Ultimately, my goal is to empower you with the confidence to intuitively understand how to provide your body with the necessary nutrients it needs.

Next Steps

The first step on my nutrition coaching pathway is to help people bring awareness to their energy requirements and their energy intake. From there, we can create an individualised plan to ensure you provide your body the right amount of energy, at the right time, not only to perform well in training but maintain optimal health.