REDs Explained, Why Underfueling Doesn't Have a Look w/ Dr. Melissa Lodge

You can run well on too little fuel for a long time. Right up until you can't.

This week, Coach Amanda and Coach Nick sit down with Dr. Melissa Lodge (PhD in exercise science and sports nutrition, RD-in-progress, and the mind behind @fed_collaborative) to unpack REDs: Relative Energy Deficiency in Sport. It's one of the most misunderstood, under-screened issues in endurance running, and it does not have a look.

We get into why low energy availability sneaks up on runners (intentional and inadvertent), why weight is a terrible way to diagnose it, and the hidden biomarkers worth advocating for on your next blood panel (hi, T3). Melissa breaks down what's actually happening beneath the surface when you underfuel: bone loss, suppressed hormones, disrupted cholesterol, and a body quietly triaging which systems it can afford to keep running.

We also cover:

• Why a "withdrawal bleed" on hormonal birth control isn't a period, and what you lose as a vital sign
• The adolescent window for bone development that you genuinely cannot get back (essential listening for parents and coaches)
• Within-day energy deficits, backloading calories, and why "I fueled my long run" isn't the finish line
• How to raise concerns with a teammate or friend without pointing fingers
• The carbohydrate revolution in endurance sport, and the trap of nailing one thing while ignoring the other 22 hours of your day

The throughline, in true Running Explained fashion: nail the basics first. Eat enough, eat often, and stop making fueling harder than it needs to be.

Bio: Melissa Lodge, PhD, is an exercise physiologist and soon-to-be RD. Her research focuses on the physiological and psychological impacts of Relative Energy Deficiency in Sport (REDs), particularly in female athletes. As a former elite runner, Melissa is especially interested in REDs prevention to improve the health and performance of athletes across the lifespan. Melissa also runs the social media platform @fed_collaborative, where she translates complex research on exercise physiology, REDs, and sports nutrition. 

Find Melissa on Instagram at @fed_collaborative.

This episode touches on disordered eating and bone health. If any of it hits close to home, please reach out to a sports-medicine-informed physician or dietitian.

Amanda IG

Nick IG

Email - Hello@runningexplained.com

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