Osteoporosis & Osteopenia from Eating Disorders

By Dennis Gibson, MD, FACP, CEDS

Anorexia & Bone Loss

Many of the characteristic behaviors of eating disorders – food restriction, purging, bingeing and overexercising – impact bone health. Bone loss is most closely tied to anorexia nervosa (AN). Those with anorexia are at a three times greater risk of bone fracture1 and up to 90% of patients with anorexia have low bone mineral density.2 

However, orthopedic problems can also present in those with bulimia nervosa, avoidant restrictive food intake disorder (ARFID) and OSFED.

There are two forms of bone mineral loss:

  • Osteopenia: a mild loss of bone mineral density
  • Osteoporosis: severe loss of bone mineral density

Osteoporosis is one of the few complications that may persist even when patients are weight restored or medically stabilized but often goes overlooked until a patient has a fracture from minimal or no trauma.3

How Eating Disorders Impact Bone Health

One of the biggest factors influencing bone health is age of onset of an eating disorder. Those who develop an eating disorder at a younge age experience more severe bone health issues than those who develop an eating disorder when they are older because they’re unable to reach peak bone mass.4 Up to 60% of adult mass is accrued during the adolescent years and by age 18 years, approximately 90% of peak bone mass has been accrued, making an eating disorder during this time devastating for bone mineral density.5

Endocrine Abnormalities

Patients who are malnourished frequently have endocrine abnormalities, which can cause bone production to decrease and bone reabsorption to increase. This can lead to low bone mineral density, putting patients at risk for:

  • Fractures and broken bones
  • Chronic pain from injury
  • Reduced strength and mobility
  • Shorter stature

Why Osteopenia & Osteoporosis Occur

Low weight & lean muscle mass

Body weight and physical activity are important determinants of bone mineral density. Low weight and malnutrition cause changes in body composition, including a decreased lean muscle mass that negatively impacts bone mineral density.1,6,7 Bone growth occurs when muscle exerts forces on bone, but this doesn’t happen with reduction in muscle mass.3

Overexercising

Although exercise can be beneficial for bone health at a healthy weight, it has a negative effect on bone density when someone is malnourished or amenorrheic (lack of a period),1,8 with one study suggesting that excessive exercise of moderate intensity resulted in further bone density loss in those with AN.7

Hormonal changes

There are multiple hormonal changes that develop with malnutrition that also negatively impact bone health. Some of the most common in patients with eating disorders are:1,4

  • Gonadal hormones (including estrogen and testosterone) are deficient in malnutrition, and both are critical for bone growth in adolescence and bone density maintenance in adults.
  • Growth hormone is one of the major anabolic hormones produced by the pituitary gland within the brain. It has numerous functions including building up of bone but is unable to do its job when someone is malnourished.
  • Cortisol, our major stress hormone, is upregulated with malnutrition to help combat some of the physiologic and metabolic changes that accompany it. However, cortisol also breaks down bone and contributes to reduction in bone mineral density.
  • Adipokines and gut hormones  have numerous metabolic effects in the body, but changes to these hormone levels with malnutrition ultimately have a deleterious effect on bone density.

Medications

Some necessary medications used to treat the comorbid medical and psychiatric conditions seen with eating disorders can negatively impact bone disease and/or vitamin D metabolism, which is very important for bone density.

Testing for & Treating Low Bone Mineral Density

Lab testing & imaging for osteoporosis

Early identification is crucial for treating and reversing bone loss. The best diagnostic tool for patients at high risk for bone loss is a DEXA (dual-energy x-ray absorptiometry) scan of the hip and lower spine. The DEXA scan can be helpful in formulating a comprehensive care plan to address any bone loss concerns and prevent further degradation.

Various laboratory investigations can measure qualitative markers on bone health and may be abnormal even before radiologic changes are noticed but aren’t routine. These include:

  • C-telopeptide
  • Alkaline phosphatase
  • Osteopontin

Can osteoporosis be reversed?

Addressing the underlying eating disorder is essential in reversing osteoporosis and improving bone health. Medical stabilization, nutrition therapy, weight restoration and – when appropriate – medication are the first steps in addressing low bone mineral density in patients with severe eating disorders.

Research suggests that supervised programs can help rebuild bone, even in those with severe bone loss.7 Low-impact and light exercise have their place, but it’s important to ensure it isn’t compulsive or too vigorous. Walking, gardening and light yoga can help under the guidance of a specialized physical therapy program for eating disorders.

References

  1. Steinman, J., & Shibli-Rahhal, A. (2019). Anorexia nervosa and osteoporosis: Pathophysiology and treatment. Journal of Bone Metabolism, 26(3), 133. https://doi.org/10.11005/jbm.2019.26.3.133
  2. Gibson, D., Watters, A., Cost, J., Mascolo, M., & Mehler, P. S. (2020). Extreme anorexia nervosa: medical findings, outcomes, and inferences from a retrospective cohort. Journal of Eating Disorders, 8(1). https://www.acute.org/research/extreme-anorexia-nervosa-medical-findings
  3. Anand, P., & Mehler, P. S. (2019). Osteoporosis recovery in severe anorexia nervosa: a case report. Journal of Eating Disorders, 7(1). doi.org/10.1186/s40337-019-0269-8
  4. Workman, C., Blalock, D. V., & Mehler, P. S. (2019). Bone density status in a large population of patients with anorexia nervosa. Bone, 131, 115161. https://www.acute.org/bone-density-status-large-population-patients-anorexia-nervosa
  5. Golden, N. H., Abrams, S. A., Daniels, S. R., Abrams, S. A., Corkins, M. R., De Ferranti, S. D., Golden, N. H., Magge, S. N., & Schwarzenberg, S. J. (2014). Optimizing bone health in children and adolescents. PEDIATRICS, 134(4), e1229–e1243. https://doi.org/10.1542/peds.2014-2173
  6. Grinspoon, S. (2000). Prevalence and Predictive Factors for Regional Osteopenia in Women with Anorexia Nervosa. Annals of Internal Medicine, 133(10), 790. https://doi.org/10.7326/0003-4819-133-10-200011210-00011
  7. Waugh, E. J., Woodside, D. B., Beaton, D. E., Coté, P., & Hawker, G. A. (2010). Effects of Exercise on Bone Mass in Young Women with Anorexia Nervosa. Medicine & Science in Sports & Exercise, 43(5), 755–763. https://doi.org/10.1249/mss.0b013e3181ff3961
  8. Howe, T. E., Shea, B., Dawson, L. J., Downie, F., Murray, A., Ross, C., Harbour, R. T., Caldwell, L. M., & Creed, G. (2011). Exercise for preventing and treating osteoporosis in postmenopausal women. Cochrane Library. https://doi.org/10.1002/14651858.cd000333.pub2
Written by
dennis gibson

Dennis Gibson, MD, FACP, CEDS

Dennis Gibson, MD, FACP, CEDS serves as a consulting physician for ACUTE. Dr. Gibson joined ACUTE in 2017 and has since dedicated his clinical efforts to the life-saving medical care of patients with…

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ACUTE Earns Prestigious Center of Excellence Designation from Anthem
In 2018, the ACUTE Center for Eating Disorders & Severe Malnutrition at Denver Health was honored by Anthem Health as a Center of Excellence for Medical Treatment of Severe and Extreme Eating Disorders. ACUTE is the first medical unit ever to achieve this designation in the field of eating disorders. It comes after a rigorous review process.

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