Malnutrition Awareness Week: Eating Disorders, RED-S, and the Hidden Faces of Malnutrition

When we think about malnutrition, many picture famine or underweight children. But malnutrition can also hide behind eating disorders and Relative Energy Deficiency in Sport (RED-S). These conditions often develop in adolescence and may persist well into adulthood—affecting both males and females, athletes and non-athletes alike.

What makes this type of malnutrition especially challenging is that it isn’t always visible. People may look outwardly healthy, but internally, their bodies are struggling to keep up with an energy and nutrient imbalance.

Eating Disorders and Malnutrition

Eating disorders—such as anorexia nervosa, bulimia nervosa, and binge eating disorder—are not just about food and weight. They are serious mental health conditions with profound nutritional consequences.

How Eating Disorders Impact Nutrition

• Anorexia nervosa: Severe restriction of food leads to calorie and protein deficiency, loss of lean body mass, and widespread micronutrient depletion (iron, calcium, vitamin D, B12). This affects immunity, cognition, fertility, and heart health.

• Bulimia nervosa: Cycles of binge eating and purging can cause electrolyte imbalances, dehydration, and damage to the digestive system. Malabsorption and deficiencies in potassium, magnesium, and zinc are common.

• Binge eating disorder (BED): While BED often leads to overweight, many individuals experience nutrient-poor overnutrition. Diets high in processed foods may lack essential vitamins and minerals, leading to “hidden hunger.”

Eating disorders are associated with some of the highest mortality rates of any mental health condition, often due to the combination of malnutrition, medical complications, and co-occurring psychological struggles.

What Is RED-S?

Relative Energy Deficiency in Sport (RED-S) happens when energy intake doesn’t meet the body’s needs for activity, growth, and recovery. It’s not just about calories—it’s about how much energy is left after exercise for basic body functions like hormone regulation, bone repair, and immune defense.

Health Effects of RED-S

• Hormonal imbalances (irregular or absent periods in females, low testosterone in males)

• Reduced bone density and increased risk of stress fractures

• Impaired immunity and slower healing

• Chronic fatigue, poor endurance, and performance decline

• Changes in mood, increased anxiety, or depression

Although RED-S was once thought to primarily affect female athletes, we now know it occurs in all genders and across many sports—including endurance running, gymnastics, weightlifting, and team sports.

Adolescence and Young Adulthood: A Critical Window

Adolescence and early adulthood are periods of rapid growth, bone building, and brain development. When nutrition is compromised during these years, the effects can last for decades.

• By late adolescence, most people have reached 90% of their peak bone mass【1】. Low energy intake, especially when paired with low calcium and vitamin D, can mean weaker bones for life.

• Hormonal disruptions from RED-S or eating disorders can interfere with puberty, fertility, and long-term metabolic health.

• Cognitive development and mental health are deeply linked to nutrition—deficiencies in iron, omega-3s, and B-vitamins can affect mood, memory, and learning.

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Warning Signs to Look For

Because malnutrition in eating disorders and RED-S doesn’t always present with extreme weight loss, it often goes undetected. Warning signs include:

• Physical: frequent injuries, stress fractures, hair loss, digestive issues, or missed periods

• Performance: declining endurance, poor recovery, or burnout in athletes

• Behavioral: restricting food groups, skipping meals, overtraining, or anxiety around eating

• Emotional: mood swings, fatigue, or withdrawal from friends and activities

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Recovery and Support

The good news is that recovery is possible. Addressing malnutrition in eating disorders and RED-S requires early recognition and a supportive, team-based approach.

• Medical care: to monitor growth, hormones, bone health, and heart function

• Nutrition support: registered dietitians can help restore adequate energy intake, balance nutrients, and rebuild a positive relationship with food

• Mental health care: therapy is crucial, as eating disorders are deeply tied to thoughts, behaviors, and self-image

• Community and coaching support: especially for athletes, open conversations about fueling, recovery, and body image can shift culture away from harmful ideals

  
  

Nourishment is Strength

This Malnutrition Awareness Week, let’s remember that malnutrition doesn’t always mean “not enough food.” It can mean not enough available energy for the body to thrive, or diets that lack the essential nutrients to sustain long-term health.

Eating disorders and RED-S remind us that nutrition is about more than calories—it’s about fueling for growth, resilience, performance, and mental well-being. By raising awareness, we can catch the warning signs earlier and create a culture that values nourishment over restriction.

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