More Than Half of Female Trail Runners Screened At Risk for RED-S. Here's What That Actually Means

A recent study published in PLOS One reported that more than half of female trail runners screened positive for eating disorder risk and low energy availability.

At first glance, those numbers are alarming.

The study found:

• 53.6% screened positive for eating disorder risk

• 55.1% screened positive for low energy availability (LEA)

• 34% screened positive for both

As clinicians and coaches, findings like these immediately grab our attention. But before we jump to conclusions, it's important to understand both what the study tells us and what it doesn't.

First, what is low energy availability?

Low energy availability occurs when an athlete doesn't consume enough energy to support both training and normal physiological function.

In simple terms, after accounting for exercise, there isn't enough energy left over for the body to perform all the jobs required to stay healthy.

Over time this can contribute to Relative Energy Deficiency in Sport (RED-S), which has been associated with:

• Bone stress injuries

• Menstrual dysfunction

• Hormonal disturbances

• Reduced recovery

• Mood changes

• Reduced performance

Most runners have heard of RED-S by now, but many still associate it with a very specific athlete profile.

The stereotypical image is a visibly underweight endurance athlete who is intentionally restricting food intake.

The reality is often far more complicated.

RED-S doesn't always look like RED-S

One of the most interesting findings from this study was that a higher BMI was associated with greater eating disorder screening risk.

That doesn't mean a higher BMI causes eating disorders, but it reinforces an important clinical point:

You cannot reliably identify athletes at risk simply by looking at them.

Many runners experiencing low energy availability or disordered eating behaviours may appear healthy, strong, and perform at a high level.

This is one reason why history taking is so important.

The athletes I worry most about are often not the ones who obviously look under-fuelled.

They're the runners who keep presenting with recurrent injuries, fatigue, poor recovery, hormonal issues, or unexplained performance plateaus.

The findings weren't just about nutrition

Another aspect of the study that caught my attention was the relationship between low energy availability and factors such as:

• Depression symptoms

• Reduced libido

• Longer participation in trail running

The authors also discussed the concept of allostatic load, which refers to the cumulative burden of training stress, life stress, recovery demands, and psychological pressures.

This is important because it challenges a common oversimplification.

Sometimes RED-S is discussed as though it is purely a nutrition problem.

Eat more, and the problem disappears.

For some athletes, that may be true.

For others, the picture is more complex.

An athlete may be managing:

• High training loads

• Poor sleep

• Work stress

• Family commitments

• Psychological stress

• Inadequate recovery

all while trying to maintain performance.

In those situations, energy deficiency may be only one piece of a much larger puzzle.

What are the limitations?

This is where it's important not to overstate the findings.

The study used screening questionnaires rather than diagnostic assessments.

That means the athletes were identified as being "at risk", not formally diagnosed with an eating disorder or RED-S.

The researchers also didn't directly measure:

• Energy intake

• Energy expenditure

• Hormone levels

• Bone density

• Metabolic markers

In addition, the study was cross-sectional, meaning it provides a snapshot in time.

We can identify associations, but we can't determine cause and effect.

For example, we can't say whether low energy availability contributed to mood disturbances or whether mood disturbances contributed to low energy availability.

The relationship may well go both ways.

What does this mean for runners and clinicians?

For me, the biggest takeaway isn't just the high prevalence numbers.

It's the reminder that RED-S screening needs to extend beyond body weight and training mileage.

When assessing runners, I think we should be routinely asking about:

• Fuelling habits

• Recovery between sessions

• Menstrual health

• Mood and stress levels

• Energy levels

• Injury history

• Sleep quality

These conversations often reveal issues long before a formal diagnosis is made.

And importantly, many of the athletes who need these conversations most won't fit the stereotypical RED-S presentation.

Final Thoughts

This study doesn't prove that more than half of female trail runners have RED-S.

What it does suggest is that a significant proportion may be experiencing symptoms or behaviours that warrant further attention.

As clinicians and coaches, that's probably the most important message.

Rather than focusing solely on biomechanics, training load, or body composition, we need to view the runner in front of us as a whole person.

Because sometimes the biggest performance limiter isn't how they're training.

It's how they're fuelling, recovering, and coping with everything else going on in life.

Reference

• Hill C, Vigne C, Basset P, Scheer V, Baud D. Screening for eating disorders and low energy availability in female trail runners: A cross-sectional study. PLoS One. 2026;21(5):e0348896.