Low Energy Availability and Relative Energy Deficiency in Sport: A Systematic Review and Meta-analysis
Gallant TL et al (2024). Sports Medicine
What did the study look at?
This systematic review and meta-analysis* had two objectives:
To determine the true prevalence of LEA and REDs among athletes with greater precision than existing estimates,
To present the first comprehensive analysis of the impact of LEA and REDs on athletic performance and injury risk.
Previous estimates from the International Olympic Committee in sports (IOC) had placed REDs prevalence anywhere between 15% and 80%, a range so wide it was of limited practical use for us practitioners. What I love about this study is that it set out to narrow that picture.
Researchers searched three major databases — PubMed, Embase, and Cochrane retrieving 3,242 articles in total.PRISMA guidelines and independent risk-of-bias assessment, 59 studies met the inclusion criteria. These studies covered 6,118 athletes across 46 studies for LEA prevalence, and 730 athletes across 8 studies for REDs prevalence.
What were the key findings?
Nearly half of all athletes, 44.7% were found to have Low Energy Availability (LEA). This broke down as 44.2% of female athletes and, interestingly, 49.4% of male athletes, directly challenging the widespread assumption that LEA and Relative Energy Deficiency in Sport (REDs) are predominantly female concerns. 63% of athletes across the REDs-specific studies were identified as being at risk of REDs - meaning nearly two thirds were already showing the downstream effects of chronic under-fuelling on their health and performance.
The health and performance consequences were wide-ranging. Athletes with LEA showed a significantly higher risk of bone stress injuries, with odds ratios of between 3.6 and 3.8 compared to athletes with normal energy availability. This means that LEA athletes were nearly four times more likely to sustain a bone stress injury. Hormonal disruption was well-documented in both sexes: in women, suppression of the hypothalamic-pituitary-ovarian (HPO) axis leading to decreased oestrogen, menstrual dysfunction, and risk of premature bone loss; in men, decreased testosterone and luteinising hormone.
On performance, athletes with LEA showed decreased training response, endurance performance, coordination, concentration and judgment. One study of female runners found that when caloric intake failed to keep pace with a 30% increase in training load, run performance declined by almost 2% and had not recovered even two weeks later. Explosive power was also impaired, with one study recording a reduction in vertical jump of up to 4.4cm following two weeks of induced LEA (the study deliverately created the energy deficit. Also, absence from training due to illness was three times more likely in athletes with LEA.
Psychological consequences included fatigue, mood disruption, irritability, elevated anxiety, and an increased predisposition to depression, even in athletes with no prior mental health history.
Overall conclusions - the authors and my take
I feel the authors' core message is clear: LEA is not a fringe issue affecting a small number of elite athletes with disordered eating. It is a widespread, under-appreciated condition with serious consequences and is commonly happening to athletes who believe they are eating healthily and training responsibly.
This is something I see in my practice frequently, and it is a topic I am deeply passionate about. The athletes sitting across from me are not reckless. They are disciplined, motivated, and doing everything the industry has told them to do, tracking their food, training hard, cutting back where they can. And yet the data is telling us that nearly half of them are under-fuelled, and that the consequences are showing up in their bones, their hormones, their mood, and their performance.
What strikes me most about these findings is that this isn't just a female story anymore. The research is showing us that male athletes are affected at an equal, if not greater rate, but the conversation in both clinical practice and the wider fitness world remains almost entirely focused on women. This needs to change.
Under-fuelling is not a character flaw. It is not a lack of discipline or awareness. In my view, it's the result of a fitness culture that has spent decades rewarding restriction and conflating leanness with health. Until we challenge that, we will keep seeing these numbers.
But this is exactly why I do what I do at Empowering Nutrition. My work isn't limited to elite athletes, it extends to everyday gym goers, working parents, recreational runners, and anyone who trains and genuinely wants to feel better in their body. What I want every single one of them to understand is that restriction is not the answer.
Fuelling yourself for the task ahead, nourishing and supporting your body is the answer. Your body is not your enemy. It is not something to be fought or overridden. It is always, without exception, trying to protect you. The least we can do is give it what it needs to do that well.
If you'd like to explore what that looks like for you specifically, this is exactly the work I do at Empowering Nutrition.
Get in touch to start the conversation.
*Definitions - Systematic review and Meta-analysis objectives:
A systematic review being a rigorous, structured process of identifying and evaluating all available research on a specific question
A meta-analysis is the statistical pooling of data from multiple studies to produce a combined result, more reliable and generalisable than any single study alone, because the larger the combined sample, the more confident we can be in the findings
Reference
Gallant TL, Ong LF, Wong L, Sparks M, Wilson E, Puglisi JL, Gerriets VA. Low Energy Availability and Relative Energy Deficiency in Sport: A Systematic Review and Meta-analysis. Sports Medicine. 2024.
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