Medical Complications of Eating Disorders

Justyna, RD
Sep 27, 2025
3 min read

Eating disorders are often seen through a psychological lens. But many providers working in this space know that the medical complications can be extensive, serious, and sometimes life-threatening. Despite the fact that eating disorders have the highest mortality rate of any mental health condition, many of their medical effects are subtle, reversible, or easily missed, especially in patients who don’t appear visibly "sick.”

In this post, we’ll review key medical complications across body systems and discuss how health providers can collaborate to support safe, effective treatment.

Why Medical Complications Are Often Overlooked

Medical instability is not always obvious. Many patients with eating disorders present as high-functioning, with stable vitals and labs that appear “normal” even as their bodies are experiencing significant strain. Patient's medical issues are often overlooked because they don't meet the stereotypical picture of undernourishment. It’s important to look beyond weight and BMI, and to look carefully for signs of functional decline, such as fatigue, dizziness, GI complaints, and cold intolerance.

Cardiovascular Complications

Cardiac issues are some of the most serious medical risks in eating disorders, especially in bulimia nervosa and other restrictive patterns.

Common complications include:

Bradycardia (heart rate <60 bpm), a physiological adaptation to conserve energy
Hypotension and orthostasis
QTc prolongation, increasing risk for arrhythmias
Atrophy of the heart muscle with prolonged malnutrition
Sudden cardiac arrest, particularly during refeeding or in electrolyte imbalance

Even patients with “normal” labs can experience dangerous cardiac effects. Monitoring EKGs and orthostatic vitals is essential during assessment and treatment.

Neurological & Cognitive Effects

Malnutrition directly impacts the brain - both structurally and functionally.

Cognitive fog, slowed thinking, and poor concentration are common
Anxiety and rigid thinking may worsen with starvation (often mistaken for personality traits)
Prolonged restriction can lead to brain atrophy visible on imaging
Risk of seizures in severe electrolyte imbalance (especially during refeeding)

These symptoms are not just psychiatric and are often neurological signs of starvation. Re-nourishment also improves cognitive function.

Hematologic Changes

Undernutrition affects bone marrow production, leading to:

Leukopenia, anemia, and thrombocytopenia
Pancytopenia in severe or prolonged cases
Increased risk for infection, though WBCs may remain deceptively normal

It’s important to note that anemia in eating disorders is typically normocytic, normochromic, and not always driven by iron deficiency.

Bone Health & Endocrine Function

Loss of sex hormones, disrupted thyroid function, and elevated cortisol levels can wreak havoc on the skeletal system.

Osteopenia and osteoporosis are common, even in teens and young adults
Amenorrhea is a sign of hypothalamic suppression, not a simple side effect
Low T3 syndrome, suppressed LH/FSH, and altered cortisol patterns are common

Bone loss is often irreversible if not caught early, ephasizing the importance of early intervention, even in patients without weight suppression.

Psychiatric & Behavioral Considerations

Though this post is medically focused, it’s worth noting that malnutrition exacerbates many psychological symptoms, including:

Irritability and emotional volatility
Obsessive thoughts about food, weight, and control
Social withdrawal and heightened rigidity

These are not personality flaws - they are adaptive brain responses to starvation, well-documented in both clinical observation and in studies like the Minnesota Starvation Experiment.

GI and Metabolic Effects

Gastrointestinal distress is one of the most common complaints among eating disorder patients.

Gastroparesis, bloating, and early satiety due to slowed GI motility
Constipation from low intake and disrupted gut signaling
Refeeding syndrome risk in undernourished patients (especially with low phosphorus, potassium, or magnesium)
Elevated liver enzymes during refeeding due to hepatic steatosis

GI complaints are always valid, but not always a sign of GI conditions. They are often a result of the body adapting to starvation and generally improve with consistent food intake and support.

The Necessity for Interdisciplinary Care

Given the complexity of medical and psychological effects, eating disorder care requires a multidisciplinary team, ideally including a primary care provider, therapist, psychiatrist, and registered dietitian.

Dietitians play a key role in:

Identify signs of malnutrition, food behaviors, and compensatory behaviors
Offering education on nutrition for healing, not dieting
Identifying early signs of medical instability
Work through barriers to meeting nutrition goals
Collaborating with physicians to address labs, vitals, and metabolic changes

Providers working with these patients should be aware that “normal labs” don’t always mean a patient is medically stable. Context, history, and symptoms matter.

Medical complications from eating disorders are real, serious, and often silent.

As a dietitian specializing in eating disorders, I offer expertise to healthcare providers to support medically informed, evidence-based care. Get in touch to see how I can support your clients.