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Do you feel fatigued? Low energy availability (LEA). What is it and how to look out for it?

Updated: Sep 28, 2023


Limited energy availability to support the normal functions of the body, once the energy expended through exercise is subtracted from the total dietary energy intake.

In short, we need to consume sufficient energy (foods) to support the activity we are doing throughout the day.

Think ‘body battery’ (as now often described on smart devices). We need to remain charged up and able to function properly.

If your body battery is low, various functions can malfunction and shut down in severe cases such as a loss of menstrual cycle or extreme fatigue.

I bring this to your attention as I see too many women beginning to increase activity and at the same time reducing calorie intake leaving them with some of the common signs below.

Common signs of LEA:

  • Inability to feel energised during activity

  • Feeling faint with activity

  • Feeling fatigued on non-active days

  • Changes in or loss of menstrual cycle

  • Changes in sleep patterns

  • Lack of motivation to do things you usually enjoy

  • Low mood & depression

  • Plateaus in performance

  • Injury

  • Gut issues

  • Illness (ie frequent colds, tonsillitis)

Symptoms that can be overlooked as LEA:

  • Plateauing in performance

LEA can be done intentionally (in the case in eating disorders) or unintentionally as I most often see, through lack of knowledge on exercise and nutrition, lack of knowledge on our own physiology and following diet fads that can be beneficial for men but not necessarily for women.

LEA is also very common in well-trained athletes due to a lack of realisation that they are under fuelling. This could be due to bad timing of nutrition, lack of particular food groups or thinking that they are eating enough when really more is needed.

How can LEA be prevented?

Planning and preparation of meals and activity is key, as well as an education on what works for women and you as an individual.

LEA can affect:

  • Bones: osteoclasts (that build bone) and osteoclasts (that eat up bone & reabsorb bone) are affected as insufficient fuel prevents these from working harmoniously to keep your bones strong.

  • For menopausal women, this is particularly important to be aware of as bone density is already on the decrease due to the decline/lack of estrogen. We need to regenerate bone through weight-bearing activity and certainly not aid weakening.

  • This can result in breaks, stress fractures or even osteoporosis.

  • The endocrine system: as estrogen can decline with LEA causing change or cessation of the menstrual cycle

  • Mood: Lack of focus/concentration, irritability, lack of motivation

  • Performance: decision making, slower responses, incoordination


Lady age 55, recreationally participating in swimming and cycling and wishing to lose belly fat/improve body composition.

She had just a coffee for breakfast, went for a steady run followed by a strength training session then drove her son 2.5hrs to university with only an apple post-training as she thought this kind of eating/exercising would result in weight loss.

Really what was happening here is increased levels of cortisol, (stress hormone and trigger to store more fat) inability to complete a really satisfying strength session and failure to consume enough protein, carbohydrates and healthy fats to maintain and build muscle from the hour of strength work she’d done. Likely she felt fatigued and hangry too!

She is also in peri-menopause, and needs to work on maintaining bone density, do heavy strength training to maintain muscle mass and strength/power for the activities she loves.

The calorie intake she describes was absolutely not enough to support activity and we could say that to some extent she’s wasting her time with strength training as the nutritional intake is key to supporting the activity and triggering muscle protein synthesis (building/maintaining muscle).

With her complaints of feeling tired at work and belly fat not shifting….this was a big LEA red flag.

Manageable, practical action steps:

We worked together on fuelling correctly around training and ensuring that she had the right education for her physiology through the menopause transition.

Things to consider:

If you're just starting out on your fitness journey, remember that fuelling well around activity is absolutely key to feeling good, getting results, maintaining good health and being happy!

If weight loss is a goal, restriction in dietary intake may be necessary, however, the non-training days are the ones to work.

For help with how to feel great, perform well, be a happy, energetic and a confident person to be around while seeing the changes you want in your body, get in touch to work with your coach.

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