Eating Disorders, Periods, and Bone Health

What's the Big Deal?

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Women commonly dread their monthly menstrual period (menses). I, on the other hand, am thrilled when a patient’s menses return after it has stopped due to an eating disorder. Even though amenorrhea (absence of a menstrual cycle in a female of childbearing age) has been removed from the DSM-5 as a diagnostic criterion for anorexia nervosa – and the resumption of menses is not the sole criterion for recovery – it remains a significant marker of the illness for many.

(As I have written before, it is not only females that suffer from eating disorders, and males suffer them at higher rates than were once thought. It bears noting that there is no equivalent to amenorrhea among male sufferers of eating disorders. Males often experience decreased testosterone, which can cause its own set of symptoms. This article, however, will address only amenorrhea.)

Sixty-six to 84 percent of women with anorexia nervosa experience amenorrhea, with an additional 6 to 11 percent experiencing light or infrequent menstrual periods. Approximately 7 to 40 percent of women with bulimia nervosa report amenorrhea. A younger adolescent may experience a delayed start of her first period as a result of an eating disorder. Amenorrhea occurs most commonly when there is low body mass, low caloric intake, and high amounts of exercise, each of which can disrupt estrogen and the other hormones that regulate menstrual periods.

Binge eating has also been found to cause menstrual disturbances.

The cessation of periods in a young person suffering an eating disorder mimics the onset of menopause. Associated symptoms may include mood changes, night sweats, difficulty sleeping, cognitive problems, and shrunken ovaries and uterus.

One of the most significant effects of these hormone changes is osteopenia, a depletion of calcium in the bones. Depleted bones are a major concern because they fracture at higher rates. In the longer term, osteopenia may lead to irreversible and chronic problems such as osteoporosis (brittle bones).

In patients with anorexia nervosa, as few as six months of amenorrhea may be associated with decreased bone mass and increased fracture rates.  Twenty months of amenorrhea has been associated with the most severe bone weakening. According to Drs. Mehler and Mackenzie,

This is especially important as almost one third of weight-restored patients with AN remain amenorrheic, likely related to ongoing energy imbalance. (2009, p. 197)

(Energy imbalance implies they are likely not eating enough or are overexercising.)

Here are 2 Myths and 1 Truth about Getting Your Period Back:

Myth:  Birth control pills can solve the problem of amenorrhea due to an eating disorder.

Birth control pills are commonly prescribed in an attempt to restart menses and to minimize bone weakness. One study surveyed doctors and found that 78 percent prescribed birth control pills for their patients with anorexia nervosa. However, research shows that birth control pills do not help to reverse osteopenia.

They cause only an artificial period and do not get at the heart of the problem or help with bone density. In fact, because the pills may mask the problem (lack of true menstruation) they are not recommended for purposes beyond birth control (non-menstruating sexually active females may still become pregnant).

According to Drs. Mehler and Mackenzie,

Moreover, an additional practical reason to refrain from using hormonal therapy is that it may cause resumption of menses which in turn may give a false sense of being cured and reinforce denial in women who are still at a low weight. (2009, p. 197)

Myth: Exercise will strengthen the bones of females with eating disorders and amenorrhea.

Although weight-bearing exercise usually helps to strengthen and build bone, this does not hold true for patients with anorexia nervosa. Misra and colleagues wrote:

[Once] they become amenorrheic, the protective effect of exercise is lost. To date, there is no evidence that high-intensity exercise in the context of weight loss and amenorrhea is protective to bone mass in [anorexia nervosa]. (2015, p.12)

Furthermore, excessive exercise may lead to estrogen deficiency and amenorrhea, exacerbating the problem.

Truth: The safest and most effective strategy to improve bone density in anorexia nervosa is returning to a weight that is appropriate as per growth chart and history, and natural restoration of menstrual function.

In females, the bones will not grow stronger without adequate estrogen, which requires a resumption or initiation of menstruation. The only treatment for resumption of menses is adequate and sustained weight restoration through refeeding and normalization of eating (including cessation of binge and purge cycles).

In many cases in which patients have improved and have been presumed cured, amenorrhea persists.  It may take up to six months for menses to resume after weight has been restored. Persistence of amenorrhea beyond this point may indicate the individual is not truly fully weight restored.

A study by Faust and colleagues (2013) demonstrated that standard eating disorder treatment goals may be insufficient to resolve amenorrhea. This study notes:

  • The standard treatment goal for adult patients is achieving 90 percent of expected body weight (based on body mass index, height, age, and sex).
  • Among adolescents with anorexia nervosa in the study, return of menses occurred on average at about 95 percent of expected body weight, “suggesting that as a minimum this weight target is necessary to restore menses in adolescents.”
  • They state, “Individual differences in weight trajectories should be taken into account,” (p. 5) – many patients may have higher setpoints (and hence, weights at which menses will resume) than population averages would suggest.
  • They point to other research that indicates that it is not atypical for adolescents to restore menses at weights more than 5 pounds above the weight that supported menses prior to the onset of amenorrhea.

Unfortunately, for some sufferers, depending on the length, severity, and age at onset of illness, bone density may never be fully recoverable, but the chances are greatly improved by early and aggressive treatment.

In conclusion, loss of menses during an eating disorder is a significant cause for concern that is best remedied by prompt weight restoration, normalization of eating behaviors, and sustained nutrition. This offers the best opportunity for reducing lifelong debilitating consequences resulting from bone weakness.


Faust, J.P., Goldschmidt, A.B., Anderson, K.E., Glunz, C., Brown, M., Loeb, K.l., Katzman, D.K., and Le Grange, D.L. (2013). Resumption of menses in anorexia nervosa during a course of family-based treatment, Journal of Eating Disorders, 1:12.

Kimmel, M.C., Ferguson, E.H., Zerwas, S., Bulik, C.M. and Meltzer-Brody, S. (2015), Obstetric and gynecologic problems associated with eating disorders. International Journal of Eating Disorders.

Mehler, P & MacKenzie, T. (2009). Treatment of osteopenia and osteoporosis in anorexia nervosa: a systematic review of the literature. International Journal of Eating Disorders, 42(3):195-201.

Misra, M., Golden, N. H. and Katzman, D. K. (2015), State of the art systematic review of bone disease in anorexia nervosa. International Journal of Eating Disorders.

Robinson, E., Bachrach, L., Katzman, D (2000). Use of hormone replacement therapy to reduce the risk of osteopenia in adolescent girls with anorexia nervosa, Journal of Adolescent Health, 26(5): 343 – 348.

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