RED-S Isn’t Just for Young Athletes: Why Midlife Women May Be Under-Fueling Their Health


Most people think of RED-S as something that happens to teenage athletes, runners, gymnasts, or elite competitors.

But low energy availability can affect active women at any age.

At MVMT MTHD, we often see women who are training hard, eating “clean,” trying to lose body fat, and doing everything they think they are supposed to do—but still struggling with fatigue, poor recovery, injuries, hormone changes, or loss of strength.

The missing piece may not be more discipline.

It may be more fuel.

What Is RED-S?

RED-S stands for Relative Energy Deficiency in Sport.

It occurs when the body does not have enough available energy to support both exercise and essential physiological functions. The International Olympic Committee describes RED-S as a condition caused by low energy availability that can negatively impact health and performance. 

This can affect:

  • Hormones

  • Bone health

  • Immune function

  • Metabolism

  • Muscle recovery

  • Cardiovascular health

  • Mood

  • Performance

Why Midlife Women Are at Risk

Many women enter their late 30s, 40s, and 50s noticing body composition changes.

The common response is:

  • Eat less

  • Do more cardio

  • Cut carbs

  • Skip meals

  • Train harder

  • Add fasting

  • Ignore recovery

But this can backfire.

During perimenopause and menopause, women may already be dealing with hormonal fluctuations, sleep disruption, stress, and changes in muscle and bone metabolism. Adding chronic under-fueling can make recovery, strength, and body composition even harder.

Dr. Stacy Sims has frequently spoken about the importance of fueling adequately, eating enough protein, and shifting away from chronic restriction for women in midlife. 

Signs You May Be Under-Fueling

Possible signs include:

  • Low energy

  • Poor sleep

  • Increased soreness

  • Loss of strength

  • Frequent injuries

  • Stress fractures

  • Irregular cycles

  • Loss of cycle

  • Low libido

  • Feeling cold often

  • Hair shedding

  • Brain fog

  • Irritability

  • Plateaued performance

  • Cravings or binge episodes

These symptoms do not automatically mean you have RED-S, but they are worth paying attention to.

Why Calories Matter for Muscle and Bone

You cannot build muscle without enough raw material.

You cannot protect bone without enough energy, protein, minerals, and hormonal support.

Low energy availability has been linked with impaired health and performance outcomes in athletes, including effects on bone and endocrine function. 

For women who are strength training, recovering from injury, or trying to improve body composition, the goal is not just to eat less.

The goal is to eat enough to adapt.

Protein Is a Priority

Protein supports muscle repair, lean mass, recovery, immune function, and healthy aging.

A large meta-analysis in the British Journal of Sports Medicine found that protein supplementation can enhance resistance training-induced gains in muscle mass and strength. 

For many active women, a practical target is often around 1.6–2.2 grams of protein per kilogram of body weight per day, depending on goals, training volume, and health status.

Carbs Are Not the Enemy

Carbohydrates support training intensity, thyroid function, recovery, sleep, and performance.

Women who train hard while eating very low calorie and very low carbohydrate may struggle to recover, especially when life stress is high.

If your body feels like it is constantly running on fumes, the answer may not be another supplement.

It may be more food.

How Physical Therapy Can Help

Performance physical therapy can help identify patterns that may be contributing to pain, injury, or poor recovery.

At MVMT MTHD, we look at:

  • Training load

  • Injury history

  • Movement quality

  • Strength deficits

  • Recovery habits

  • Nutrition red flags

  • Bone stress risk

  • Return-to-training strategy

We do not diagnose RED-S through physical therapy alone, but we can recognize when someone’s body is not adapting well and help guide them toward the right support.

Bottom Line

If you are training hard but constantly tired, injured, sore, or stuck, you may not need to push harder.

You may need to fuel better.

Women’s health is not built through depletion.

It is built through strength, nourishment, recovery, and a body that has enough energy to adapt.