REDs in Athletes: What Every Coach and Parent Should Know

There's a condition affecting young athletes that most coaches and parents have never heard of — and that's exactly why it's dangerous. It's called REDs: Relative Energy Deficiency in Sport. It doesn't announce itself. It shows up as a nagging stress fracture, a performance plateau nobody can explain, or a kid who seems a little "off" and nobody can say why.

I recently sat down with Laura Reece, MS, RD, CSSD, LDN, Director of Sports Nutrition at WHSP Medical (Women's Health, Sports & Performance), for an episode of my podcast, Strong, Inside and Out. Laura has spent her career in this exact space — from Boston Children's Hospital's female athlete program to building her own private practice for a decade, to co-founding WHSP Medical with Dr. Kate Ackerman. If anyone can make REDs make sense, it's her.

Here's what every coach, parent, and athlete should walk away understanding.

What REDs Actually Is

REDs stands for Relative Energy Deficiency in Sport. In plain terms: it's what happens when an athlete is consistently expending more energy than they're taking in. The body doesn't have enough fuel to cover both training demands and basic physiological function — so something has to give.

Laura's analogy stuck with me: think of it like a phone in low-power mode. When the battery gets low, the phone doesn't just slow down — it starts shutting off non-essential features to protect what's left. Your body does the same thing. Reproductive function, bone remodeling, digestion, immune response, even mood regulation — all of it can get deprioritized when energy is scarce.

This Isn't Just a "Female Athlete" Issue

For years, this territory was described under the "Female Athlete Triad" — under-fueling, hormonal disruption, and menstrual irregularity. REDs is a broader, more accurate model. It affects athletes of any gender, and its effects extend well beyond hormones — touching bone health, GI function, iron status, and mental health.

The Myth of "But They're Losing Weight, So It's Working"

One of the most counterintuitive points from our conversation: under-fueling can look like it's working at first. Athletes may see an initial performance bump. This is exactly what makes REDs so easy to miss — the early signal often looks like progress, not a problem. The decline shows up later, and by then it's harder to untangle from "just a bad season."

Warning Signs Coaches and Parents Can Actually Catch

You don't need a clinical background to notice these:

• Stress injuries — especially bone stress injuries that seem to come out of nowhere or heal slowly

• Persistent fatigue that doesn't track with training load

• Performance plateaus or declines despite consistent effort

• Changes in demeanor — irritability, withdrawal, increased anxiety around food or training

• GI symptoms like constipation or bloating

• Missed or irregular periods, low libido, or other hormonal shifts

None of these on their own is a diagnosis. But a cluster of them, especially alongside a change in eating or training behavior, is worth paying attention to.

A Better Way to Ask "Are You Eating Enough?"

One of my favorite parts of this conversation was practical: how do you actually talk to an athlete you're worried about? Laura's advice — don't lead with the direct question. "Are you eating enough?" almost never gets an honest answer. Instead, lead with a specific observation: "I noticed you've been more tired at practice this week" or "Your times have dipped a bit — how are you feeling?" Specific, non-accusatory observations open a door that a direct question slams shut.

It's Not Just Field Sports

Laura also works as a consulting dietitian for the Boston Ballet, and our conversation touched on how REDs shows up differently in aesthetic sports like dance, where leanness is often tied to the art form itself. She pointed me toward Project RED-D, an organization doing dedicated work to educate dancers, teachers, and healthcare providers on the dance-specific expression of this condition.

Where to Get Help

WHSP Medical treats REDs through an interdisciplinary team — nutrition, sports psychology, and medical care working together, often using nutrition or psychology services as an accessible entry point before an athlete is ready for fuller care. Importantly, WHSP Medical accepts insurance, so cost isn't necessarily the barrier people assume it is.

Why This Matters to Me as a PT

As a physical therapist who screens young athletes regularly through our Movement Physical — our twice-yearly, roughly 20-minute 3D Kinotech movement assessment — I see the downstream effects of under-fueling all the time: the stress reaction that won't heal, the athlete who keeps re-injuring the same tissue, the plateau that strength work alone can't explain. Movement screening catches biomechanical risk. Conversations like this one are what catch the fueling risk sitting underneath it. Both matter.

If you coach, parent, or are an athlete yourself and any of this sounds familiar, don't wait for a stress fracture to start the conversation.

Want to hear the full conversation? Listen to this episode of Strong, Inside and Out, and check out the show notes for links to WHSP Institute's REDs resources, the REDs Conceptual Models for health and performance, and Project RED-D.

Ashley Katzenback, PT, DPT, is the founder of Cape Concierge Physical Therapy, a concierge-model physical therapy practice serving Cape Cod, the South Shore, and Greater Boston. She hosts Strong, Inside and Out, a podcast built on the idea that education is the intervention.