Medical Complications
Eating disorders affect every organ system. Understanding these complications underscores the medical seriousness of these illnesses — and the good news that most are reversible with proper treatment.
Every System
Can be affected
Heart, brain, bones, GI, hormones
Most
Are reversible
With nutritional rehabilitation
Bone Loss
Notable exception
Risk of permanent effects
Hidden
At any weight
You can't see vital signs
Eating disorders are medically dangerous at any weight. The physical effects of restriction, bingeing, and purging can affect the heart, brain, bones, hormones, and digestive system. While this information can be frightening, the good news is that most complications often reverse with proper treatment and nutritional rehabilitation.
TL;DR — Key Takeaways: EDs affect every organ system. Most complications are often reversible with treatment. Bone loss is a notable exception. Cardiac issues are the leading cause of ED-related death. Refeeding syndrome is preventable with medical supervision. You can't tell medical severity by looking at someone.
A note before reading: This page contains detailed medical information that some people find distressing. If this feels overwhelming, it's okay to pause. You don't need to read everything at once. The key message is simple: EDs have real medical effects, most are treatable, and getting help matters.
Medical emergency warning signs: Fainting, chest pain, heart palpitations, severe dizziness, blood in vomit or stool, severe abdominal pain, or thoughts of suicide require immediate medical attention. Go to the emergency room or call 911.
Often reversible with treatment
May be partially reversible
Risk of permanent effects
Cardiovascular System
Heart & Circulation
Cardiac complications are a leading cause of eating disorder-related death
Bradycardia
Abnormally slow heart rate (often <60 bpm, sometimes <40 bpm). The heart slows to conserve energy during starvation.
Often reversible
Hypotension
Low blood pressure. Can cause dizziness, fainting, especially when standing (orthostatic hypotension).
Often reversible
Cardiac Muscle Loss
The heart muscle shrinks during starvation, reducing cardiac output by up to 45%.
Often reversible
Arrhythmias
Irregular heart rhythms, often due to electrolyte imbalances. Can be life-threatening.
Often reversible
QT Prolongation
Delayed electrical recovery of the heart. Increases risk of sudden cardiac death.
Often reversible
Mitral Valve Prolapse
Heart valve abnormality that can occur with weight loss. Usually not dangerous.
Often reversible
Pericardial Effusion
Fluid around the heart. Occurs in ~25% of people with AN. Rarely dangerous.
Often reversible
Sudden Cardiac Death
The most serious risk — can occur from arrhythmias or electrolyte disturbances.
Preventable with treatment
Bone Health
Bone Mineral Density
One of the few complications that may not fully reverse
Osteopenia
Mild bone loss. Present in up to 92% of women with AN. Bones become less dense and weaker.
Partially reversible
Osteoporosis
Severe bone loss. Present in ~40% of women with AN. Significant fracture risk.
Risk of permanent effects
Increased Fracture Risk
3x higher lifetime risk of fractures. Can affect spine, hip, wrist, and other bones.
Risk decreases with recovery
Stunted Peak Bone Mass
Adolescence is critical for bone building. EDs during this time prevent reaching peak bone mass.
Risk of permanent effects
Why bone loss happens: Malnutrition disrupts hormones (estrogen, testosterone, cortisol) that regulate bone metabolism. Low estrogen increases bone breakdown; high cortisol decreases bone formation. Weight restoration and hormone normalization are the primary treatments.
Brain & Neurological
Brain Structure & Function
The brain is remarkably resilient — most changes reverse with recovery
Brain Atrophy
Visible shrinkage of gray and white matter on MRI. The "starved brain" effect.
Often largely reversible
"Brain Fog"
Difficulty concentrating, memory problems, slower thinking. Very common during active illness.
Often reversible
Cognitive Inflexibility
Rigid thinking, difficulty switching tasks or perspectives. May persist into early recovery.
Often reversible
Peripheral Neuropathy
Tingling, numbness in hands and feet due to vitamin deficiencies (especially B vitamins).
Reversible with repletion
Seizures
Can occur from electrolyte imbalances or hypoglycemia. Medical emergency.
Preventable
Sleep Disturbances
Insomnia, fragmented sleep, reduced REM sleep. Common across all eating disorders.
Often reversible
Gastrointestinal System
Digestive System
GI symptoms are common but usually resolve with normalized eating
Gastroparesis
Delayed stomach emptying. Causes bloating, fullness, nausea after eating. Very common in AN.
Often reversible
Constipation
Slowed gut motility from restriction. Can be severe. Laxative abuse worsens it.
Often reversible
Bloating & Discomfort
Very common during refeeding. The gut needs time to readjust to normal food intake.
Temporary
SMA Syndrome
Superior mesenteric artery syndrome — compression of the duodenum. Can occur with severe weight loss.
Reversible with weight gain
Elevated Liver Enzymes
AST and ALT elevation from autophagy (cell breakdown) during starvation or refeeding.
Often reversible
Pancreatitis
Inflammation of the pancreas. Can occur from bingeing or refeeding. Painful, requires treatment.
Usually reversible
Endocrine (Hormones)
Hormonal Changes
The body adapts to starvation by altering hormone production
Amenorrhea
Loss of menstrual periods in females. Due to hypothalamic suppression. Very common in AN.
Often reversible
Low Testosterone
In males, can cause low libido, erectile dysfunction, loss of muscle mass.
Often reversible
Elevated Cortisol
Stress hormone stays elevated. Contributes to anxiety, bone loss, and immune suppression.
Often reversible
Euthyroid Sick Syndrome
Low T3 and T4 (thyroid hormones) with normal TSH. Body conserves energy by slowing metabolism.
Often reversible
Growth Hormone Resistance
Can impair growth in adolescents. May affect final adult height if ED occurs during puberty.
Depends on timing
Fertility Issues
Irregular ovulation, difficulty conceiving. Usually normalizes with weight restoration.
Usually reversible
Purging Complications
Purging behaviors — whether through vomiting, laxatives, diuretics, or excessive exercise — cause specific medical complications beyond those from restriction alone.
Vomiting
Dental erosion, swollen salivary glands, esophageal tears, electrolyte imbalances (low potassium), calluses on knuckles
Laxatives
Chronic constipation, dependence, dehydration, electrolyte imbalances, rectal prolapse, colon damage
Diuretics
Severe dehydration, kidney damage, dangerous electrolyte imbalances, rebound edema
Electrolyte Imbalances
Purging of any kind can cause dangerous electrolyte disturbances:
- Hypokalemia (low potassium): Can cause fatal cardiac arrhythmias
- Hypochloremia (low chloride): From vomiting stomach acid
- Hypomagnesemia (low magnesium): Muscle weakness, cardiac effects
- Metabolic alkalosis: From loss of stomach acid
Dental Effects of Vomiting
Stomach acid erodes tooth enamel:
- Enamel erosion (especially back of front teeth)
- Increased cavities
- Tooth sensitivity
- Discoloration
- Gum disease
Note: Dental damage is not reversible, though progression can be stopped.
Refeeding Syndrome
⚠️ Refeeding Syndrome
A potentially fatal complication of nutritional rehabilitation in severely malnourished patients. This is why medical monitoring during refeeding is essential.
What Happens
- When refeeding begins, the body shifts from fat/protein metabolism to carbohydrates
- Insulin surges, driving electrolytes (especially phosphorus) into cells
- Blood levels of phosphorus, potassium, and magnesium drop dangerously
- Thiamine (vitamin B1) is rapidly depleted
- Can occur within the first 5 days of refeeding
Symptoms & Complications
- Cardiac arrhythmias, heart failure
- Respiratory failure
- Seizures, confusion, coma
- Muscle weakness, rhabdomyolysis
- Edema (fluid retention)
- Can be fatal if unrecognized
Who Is at Risk?
- Very low body weight (BMI <16)
- Little to no food intake for >5-7 days
- Already low phosphorus, potassium, or magnesium
- History of alcohol use disorder
- Recent unintentional weight loss >15%
- Laxative, diuretic, or insulin misuse
Prevention
- Slow refeeding: Start low, advance gradually
- Electrolyte monitoring: Check labs frequently
- Thiamine supplementation: Before refeeding starts
- Medical supervision: Specialized ED medical care
- Correct deficiencies: Replace electrolytes as needed
Refeeding syndrome is preventable with proper medical monitoring and experienced care.
Other Complications
Additional Medical Effects
Skin, hair, blood, and immune system changes
Lanugo
Fine, downy hair growth on face and body. The body's attempt to stay warm.
Often reversible
Hair Loss
Thinning or falling out of scalp hair. Due to nutritional deficiencies.
Often reversible
Dry Skin & Brittle Nails
Skin becomes dry, cracked; nails become brittle. From dehydration and deficiencies.
Often reversible
Cold Intolerance
Feeling cold all the time. Body can't regulate temperature well due to low body fat.
Often reversible
Anemia
Low red blood cells. Causes fatigue, weakness, pale skin. From nutritional deficiencies.
Often reversible
Leukopenia
Low white blood cells. Present in ~50% of AN patients. Surprisingly, infection risk isn't elevated.
Often reversible
✓ Key Takeaways
✓ EDs affect every organ system — they are medically serious
✓ Most complications are reversible with proper treatment
✓ Bone loss is a notable exception — may not fully reverse
✓ Purging causes specific additional complications
✓ Refeeding syndrome is preventable with medical supervision
✓ Medical monitoring is essential during treatment
✓ You can't tell medical severity by looking at someone
✓ Cardiac complications are a leading cause of ED death