Bradycardia: The Most Common Complication of Eating Disorders

Bradycardia, or low heart rate, is a common and potentially serious complication of eating disorders, affecting up to 95% of individuals with anorexia nervosa. Bradycardia warning signs include fatigue, dizziness, chest pain, but sometimes doesn’t have any signs. Distinguishing between bradycardia due to an eating disorder vs. having an "athletic heart" is crucial, as malnourished individuals may require hospitalization for medical stabilization. Nutritional rehabilitation and medical stabilization are key to reversing bradycardia and ensuring long-term recovery.

Low Heart Rate in Eating Disorders

Bradycardia is a condition characterized by an abnormally low heart rate, defined as fewer than 60 beats per minute (bpm), compared to the normal range of 60-100 bpm. Bradycardia is one of the most common medical complications in patients with anorexia nervosa, affecting up to 95% of patients.¹

Bradycardia usually occurs with significant weight loss. Although it is most common in severely underweight patients, it can also happen in those who are not underweight but have lost a substantial amount of weight, such as individuals with atypical anorexia.²

However, bradycardia may not cause any symptoms, highlighting the need for healthcare professionals to evaluate patients at risk for such a serious complication and other cardiac issues.

How Do Eating Disorders Cause Bradycardia?

The cause of bradycardia in individuals with eating disorders may stem from increased vagal (parasympathetic) tone as an adaptive response to food restriction and low caloric intake, where the parasympathetic nervous system slows the heart to conserve energy and maintain normal body functions.¹ However, this remains uncertain since not all studies have observed heightened parasympathetic tone.

4 Signs of Bradycardia

Hypotension

Although hypotension (low blood pressure) doesn’t necessarily indicate bradycardia, the two often occur together because of similar underlying causes.³ Increased parasympathetic activity, along with efforts to compensate for reduced metabolic needs and decreased blood volume due to dehydration or purging, contributes to the low blood pressure seen in individuals with eating disorders.

Other contributors can include:

• Medications to treat co-occuring medical conditions
• Decreased blood return to the heart upon standing due to sarcopenia

Patients with abnormally low blood pressure can experience:

• Dizziness
• Nausea
• Fatigue
• Blurred vision
• Cold or clammy skin
• Confusion

Dizziness, lightheadedness or fainting

Low blood pressure can limit the supply of oxygen to the brain, causing episodes of dizziness, lightheadedness or fainting.

Shortness of breath or chest pain

Inadequate supply of blood to the heart due to low blood pressure can cause shortness of breath or chest pain.

Fatigue

Poor blood flow to the brain and other organs can also impair energy production, leading to fatigue.

Identifying Bradycardia

It can be challenging to determine whether a low heart rate requires monitoring or immediate attention. Heart rates below 40 bpm (or 45 bpm for adolescents) necessitate hospital admission and cardiac monitoring, as outlined in the 2023 American Psychiatric Association Practice Guidelines for the Treatment of Patients with Eating Disorders:⁴

• Under 60 bpm: A heart rate of under 60 bpm is considered slower than normal for most adults, although athletic adults and young adults may experience a resting heartbeat of under 60 bpm that drops even lower during sleep. If an individual with an eating disorder has a heart rate under 60 bpm, an evaluation may be warranted.
• Under 50 bpm: A heart rate consistently below 50 bpm is more likely to be a cause for concern. However, some healthy, active adults have heart rates under 50 bpm, particularly endurance athletes. Per the American Psychiatric Association, individuals with eating disorders who have a heart rate lower than 50 bpm may require medical hospitalization for assessment and treatment.
• Under 40 bpm: A heart rate consistently under 40 bpm is most likely a cause for concern in malnourished individuals and requires additional medical monitoring.

What’s the Difference Between Bradycardia & an Athletic Heart?

Individuals with a severe eating disorder may already know about their low heart rate, and some might think it's due to having an “athletic heart” or being physically active. While they may exercise often and even perform at a higher athletic level, a bradycardic heart and an athletic heart are not the same, since the low heart rate seen in those with eating disorders is not caused by athletic conditioning.¹

Identifying Bradycardia from Malnutrition

Exertion test

One way to distinguish between an athletic or malnourished heart is to ask patients to mildly exert themselves, like walking across the room or standing up from a lying position. Patients with bradycardia from malnutrition will show an abnormally elevated heart rate (tachycardia) with minimal activity. On the contrary, a healthy athlete will not have a significant increase in heart rate with these activities.

Ultrasound imaging

You can confirm the health of the heart by ordering ultrasound imaging. In patients with severe eating disorders, imaging may show small, thin cardiac chambers that wouldn’t be seen in healthy athletes.

Treatment for Bradycardia

Medical stabilization

Patients with eating disorders, a heart rate below 40 bpm and/or hypotension should be admitted for medical stabilization. At this stage of cardiac distress, patients are likely experiencing other serious medical complications related to their illness, and stabilization in a specialized inpatient setting is often necessary before starting an eating disorder treatment program at a lower level of care.

Nutritional rehabilitation

Bradycardia typically resolves with nutritional rehabilitation and improved body weight by treating the underlying eating disorder.

Get Help for Bradycardia

If you have an eating disorder and are experiencing bradycardia, your body is under considerable strain. Medical stabilization and nutritional rehabilitation are essential to address and reverse the life-threatening complications of eating disorders. No matter how long you’ve been struggling, support and treatment are available.

Take the first step with a free assessment.

References

1. Yahalom, M., Spitz, M., Sandler, L., Heno, N., Roguin, N., & Turgeman, Y. (2013). The significance of bradycardia in anorexia nervosa. International Journal of Angiology, 22(02), 083–094. https://doi.org/10.1055/s-0033-1334138
2. Sawyer, S. M., Whitelaw, M., Grange, D. L., Yeo, M., & Hughes, E. K. (2016). Physical and psychological morbidity in adolescents with atypical anorexia nervosa. PEDIATRICS, 137(4). https://doi.org/10.1542/peds.2015-4080
3. Mehler, P. S., & Andersen, A. E. (2017, November 29). Eating Disorders: A Guide to Medical Care and Complications (third edition). Johns Hopkins University Press.
4. Crone, C., Fochtmann, L. J., Attia, E., Boland, R., Escobar, J., Fornari, V., Golden, N., Guarda, A., Jackson-Triche, M., Manzo, L., Mascolo, M., Pierce, K., Riddle, M., Seritan, A., Uniacke, B., Zucker, N., Yager, J., Craig, T. J., Hong, S., & Medicus, J. (2023). The American Psychiatric Association Practice Guideline for the Treatment of Patients with Eating Disorders. American Journal of Psychiatry, 180(2), 167–171. https://doi.org/10.1176/appi.ajp.23180001