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Skeletal Effects of Anorexia
(Osteoporosis and Related Bone Diseases-National Resource Center)

Approximately one percent of adolescent girls develop anorexia nervosa, an eating disorder characterized by an irrational fear of weight gain. The condition usually begins around the time of puberty and is associated with restricted eating and extreme weight loss. Anorexia is a mental disorder with significant physical consequences. Affected individuals typically experience an absence of menstrual periods and other health problems which negatively impact bone density.

Anorexia and Bone Loss

Both nutritional and endocrine factors set the stage for bone loss in anorectics. One of the most significant factors is estrogen deprivation. Low body weight causes the body to stop producing estrogen. This disruption in the menstrual cycle, known as amenorrhea, is associated with estrogen levels similar to those found in postmenopausal women. Significant losses in bone density typically occur.

Elevated glucocorticoid levels also contribute to low bone density in anorectics. Sufferers tend to have excessive amounts of the glucocorticoid "cortisol," which is known to trigger bone loss. Other factors, such as a decrease in the production of growth hormone and growth factors, low body weight (apart from estrogen loss), calcium deficiency, and malnutrition have also been proposed as possible causes of bone loss in girls and women with the disorder.

The Scope of the Problem

Bone loss is a well established consequence of anorexia. Recent studies suggest that not only is osteopenia very common, but that it occurs early in the course of the disease. Key studies have found significant decreases in bone density in anorectic adolescents. For example, affected teens have been shown to have spinal density 25% below that of healthy controls. Up to two thirds of teens with the disorder have bone density values more than two standard deviations below the norm.

Studies suggest that half of peak bone density is achieved in adolescence. Anorexia typically develops between mid to late adolescence, a critical period for bone accretion. Affected teens experience decreases in bone density at a time when bone formation should be occurring. Studies have shown that anorectic girls are less likely to reach their peak bone density and are at increased risk for osteoporosis and fracture throughout life.

Anorexia in Men

According to the American Anorexia Bulimia Association, approximately ten percent of eating disorder sufferers are male. While men are much less commonly affected by anorexia than women, research suggests that male victims also experience significant bone loss. A recent study at the University of Iowa found substantial decreases in spinal bone mineral density in anorectic college men. Researchers speculated that weight loss, restricted dietary input and testosterone deficiency may be responsible for the low bone density found in men with the disorder.

Managing Bone Loss

The aim of medical therapy for anorectic females is weight gain and the return of regular menstrual periods. Research from Children's National Medical Center in Washington D.C. suggests that menses usually resumes when girls have achieved 90% of the standard body weight for their age and height. While calcium intake has not necessarily demonstrated a therapeutic value, a nutritionally sound diet, including adequate calcium and vitamin D, is recommended.

The effect of exercise on bone recovery is not clear. Some studies have identified a skeletal benefit from weight bearing activity in anorectics. However, the potential benefits of exercise need to be weighed against the risk of fracture, delayed weight gain, and exercise induced amenorrhea. The impact of estrogen preparations on bone density in affected girls and young women is also unclear. Estrogen may offer a limited benefit in some patients, but it should not be a substitute for nutritional support.

Is Recovery of Bone Loss Possible?

The longer the duration of anorexia nervosa, the less likely it is that bone mineral density will return to normal. While the possibility for complete recovery of normal bone mineral density is low, weight gain and the resumption of menses increase the likelihood that some gains in bone density will occur. Unfortunately a significant number of girls and young women will suffer a permanent reduction in bone density which places them at risk for osteoporosis and fracture throughout their lifetime.

Revision Date: 8/2001