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REDS Signs and Symptoms: How Relative Energy Deficiency in Sport Impacts the Entire Body

Awareness of REDS (Relative Energy Deficiency in Sport) has grown in recent years, but the conversation is still too often limited to the correlation between underfueling and irregular or absent menstrual cycles in female athletes. While missing a period can be an important indicator, REDS signs extend far beyond reproductive health. There are MANY other bodily systems that are impacted by underfueling and inadequate recovery. 

It’s important for providers to understand the broad range of Relative Energy Deficiency in Sport symptoms and how they may be related to underfueling. It’s equally as important for athletes to be empowered in understanding their own bodies and what underfueling may be causing throughout their entire body. Not to mention, some female athletes with REDS may never lose their period (or lose weight!) and REDs does not only affect female athletes.

In this blog post, I’m sharing a breakdown of key REDS signs and symptoms, questions to ask, and red flags to watch out for. 

So You Suspect REDS? Here’s What to Ask Your Athlete

Growth and Development

  • If an adolescent, have they fallen off their growth curve? (Weight usually falls off the curve before height.)
    • If so, use growth charts to establish a weight range target, knowing that the range will continue to grow as an athlete does.
  • If >20 years old, ask for growth charts.
    • Has there been any changes on the curve for weight then assessed for readjusted natural weight range?
    • If there was a drop on the curve for weight, assess for potential height influence as well.

Psychological Health

  • What is their motivation for training?
  • How is their sleep and stress level?
  • Are they engaging in social engagements or are they becoming more withdrawn and isolated?
  • Are they thinking about food constantly or obsessively planning food intake?

Metabolic Function

  • Is lab work abnormal? The liver may not have enough storage of key nutrients.
  • Are Vitamin D levels <32 ng/mL?
    • Levels >40 ng/mL are preferable.
  • Are they cold often, do they wear jackets in warm temperatures often, do they have lanugo on their face or arms? Body temperature may be reduced to save energy.

Sexual and Reproductive Health

  • Has there been a change in sex drive (age appropriate)?
  • For athletes assigned female at birth (AFAB), do they get regular periods (every 21-35 days)?
    • Has the heaviness of their period changed?
    • Do they notice ovulatory symptoms, and is the timing between those symptoms and the onset of a period consistent or lengthening?
    • If they have started missing a period, they’ve likely been in an energy deficiency for a few months prior to the loss of period.
  • For athletes assigned male at birth (AMAB), has there been a decrease in their average morning erections?

Gastrointestinal Health

  • What is “normal” digestion for this athlete?
  • Do they get full quickly? How often do they have a bowel movement?
  • Are they feeling constipated/bloated compared to what is normal for them? (Assess for body image distress related to bloating).
  • Have they cut out foods, and if so, why? Were they able to tolerate the removed foods prior to REDs?
  • What is their level of stress most days? What is their level of stress during training?

Bone Health

  • Have they had bone stress injuries? If so, how many?
  • Do they have “normal” bone density?
    • The IOC and ACSM define “normal” bone density for athletes as a Z-score of -1 or greater.
    • Within a year of a missing period or restrictive eating patterns/suspected REDs, an athlete needs a baseline DEXA scan.

Immunological Health

  • Are they getting sick often? 
  • Are they taking longer to recover from illness than normal or expected? 
  • Does the athlete tend to get sick more often when training ramps up?
    • Athletes with LEA may have decreased immunity.
    • Screen for low glucose availability with compromised immune systems.

Hematological Health

  • Is their ferritin low or suboptimal? Iron plays a bi-directional role in energy availability.
    • Ferritin >30 ng/mL is preferable.

Endocrine System

  • Are their thyroid labs abnormal? Thyroid health may be compromised to conserve energy.
    • T3 will be low; TSH can be low, normal, or slightly elevated.
  • Is their vitamin D low or suboptimal? Vitamin D has a role in regulating iron and thyroid pathways as well as the bone/immune system.
    • Vitamin D levels should be >40 ng/mL.

Cardiovascular Health

  • Is their resting heart rate <60 bpm (bradycardia)?
    • Assess for athletic vs. starved heart using Dr. Gaudiani’s walking test.
      • A change of 75% or more from resting to walking is likely significant (blood pressure remains fairly static).
    • A nourished/athletic heart = no issues walking down the hall.
    • A starved heart = has to work hard to walk down the hall.
  • HR trends: HR rises upon waking and RHR decreases during the day. RPE increases to do the same load of work. 

Why a Whole-Body Lens Matters When REDS Signs Are Present

REDS isn’t confined to a single lab marker, injury, or symptom. It is a multi-system condition that can quietly affect everything from mood to metabolism, bone health, and immunity. Athletes often present with only one or two warning signs… maybe fatigue, stress fractures, or irregular digestion, while other symptoms remain hidden until performance and well-being are significantly impacted.

By recognizing REDS as a condition that touches every body system, athletes and providers can move beyond focusing solely on weight changes or menstrual health. This broader lens ensures earlier detection, better treatment, and most importantly, a stronger foundation for both long-term health and athletic performance.

REDS Support for Athletes and Providers

Recognizing REDS signs and symptoms requires a whole-body approach. Athletes deserve providers who ask the right questions, and providers need to stay educated on this evolving condition.

If you’re an athlete looking for support as you train, perform, and recover, join my Are You RED-Y Roadmap Nutrition Challenge!

If you’re a provider looking for more information, training, and clinical practice on REDS, join my REDS Provider Masterclass!