What You Should Know About Anorexia Nervosa and Bone Health

Recovery from an eating disorder is really hard. Unfortunately, the negative effects of that occur as a result of the eating disorder often persist long after recovery. It is hard to undo the mental and psychological aspects of anorexia or bulimia nervosa, but it may be just as hard, if not impossible, to undo the damage done to body.

What are some of the long-term health effects of eating disorders? What do patients with eating disorders – recovered or not – have to live with, for years, often decades, after recovery?

A really common consequence of anorexia nervosa is osteoporosis: thinning of bone tissue and loss of bone density. Unlike delayed gastric emptying – another consequence of EDs – which can make every meal a nightmare (particularly for someone recovering from an eating disorder): acid reflux, stomach pain and abdominal bloating are just some of the symptoms, bone density loss is easy to overlook. You don’t feel its effects (not initially, anyway), you probably wouldn’t even know it is happening. Many are unaware of just how quickly bone health can deteriorate and how difficult it may be to repair the damage. 

Probably more than half of young women  with anorexia nervosa develop osteoporosis,  and relatively quickly. Baker et al obtained bone scans in a series of 56 young women, mean age 27 years, who had had an eating disorder for  a mean of about 10 years, and found that the bone mineral density in the femur was below the critical fracture threshold in 42 (75%).

A review paper by Dr. Kathryn Teng, published last year in the Cleveland Clinic Journal of Medicine, provides a concise overview of the prevalence, risk factors and treatment of osteoporosis in patients with anorexia nervosa.

The mean age of onset for anorexia nervosa is in the early to mid teens, a time which coincides with puberty, rapid growth and bone development. Although bone density continues to increase into the 20’s, the majority occurs during adolescence. According to Teng, 40-60% of bone mass in women, is gained between the ages of 11 and 14.

This overlap is important because it can have huge implications later in life:

 …small differences in bone density can have significant clinical implications later in life: a 5% increase in bone density significantly decreases fracture risk, whereas a 10% decrease in adult  bone mineral density is associated with a two to three times higher risk of fracture…

What causes bone density loss in anorexia nervosa? The main factors are low body weight (a risk factor that is independent of anorexia nervosa – that is, naturally thin people are also at a higher risk of osteoporosis) and amenorrhea (the absence of menses). In anorexia, the absence of menses results from hypothalamic dysfunction. The hypothalamus regulates appetite, thirst, mood, libido and body temperature, among other things. In AN, chronic restriction suppresses the release of a hormone called the gonadotropin-release hormone, which leads to a decrease in FSH (follice-stimulating hormone) and LH (luteinizing hormone), leading to a “prepubertal low-estrogen state.” This results in hypothalamic (also known as secondary) amonrrhea. Moreover, the duration of amenorrhea appears to be correlated with the extent of bone density loss.

The list below is modified from Table 1 in the Teng (2011) paper.



  • low body weight appears to contribute to bone density loss independently of menses (that is, undernutrition in the presence of menses is still detrimental to bone health and conversely, weight restoration even without return of menses is beneficial)

Deficiency in insulin-like growth factor 1 (IGF-1)

Low androgen levels


  • elevated levels of the stress hormone cortisol have been noted in patients with AN
  • levels of cortisol are inversely correlated with levels of a bone-forming protein and this may lead to loss of bone density

Increased osteoprotegerin

  • helps preserve bone density
  • appears to be higher in females with AN than controls, may be released in an attempt to preserve bone density

There may be potential roles for leptin (leptin role in bone health), ghrelin and obestatin in regulating bone density, but further studies are necessary. 

Teng also summarizes common treatments for bone density loss and the evidence supporting each treatment in anorexia nervosa patients.


When it comes to prevention and treatment of low bone density, weight restoration is by far the most effective and evidence-based approach. Weight gain normalizes hormone levels which play important roles in regulating bone health.

Although vitamin D supplements haven’t been shown (consistently) to improve or prevent bone density loss in AN patients, given that most individuals do not get enough vitamin D, supplementation, as Teng writes, “is almost universally recommended.” (Vitamin D and bone health)

What about hormone (estrogen) therapy?

This is where premenopausal and postmenopausal women differ. In postmenopausal women, hormone replacement therapy is effective in improving bone density (here is a nice summary of the benefits and risks of HRT in preventing osteoporosis in postmenopausal women). The reason that HRT does not seem to be of much benefit to premenopausal women is likely due to the fact that the mechanisms underlying bone loss are different – the physiology is just not the same.

Despite the documented association between anorexia nervosa and estrogen deficiency and the strong correlation between osteoporosis and the duration of amenorrhea, most studies have found no improvement in bone mass with hormonal therapy. In particular, three randomized, placebo-controlled trials have been published to date, and not one showed a significant improvement in bone mineral density with estrogen therapy compared with placebo in patients with anorexia nervosa… [Moreover] restoring regular menstrual cycles with oral contraceptive pills will not normalize the metabolic factors that impair bone formation, health, and performance and is not likely to fully reverse low bone mineral density…

Weight-bearing exercise is often suggested to postmenopausal women to prevent bone density loss. However, the effects weight-bearing exercise appears to benefit only the weight-bearing sites, and its effect in patients with AN is not fully determined. Moreover, due to the high prevalence of compulsive exercise in AN, caution should be exercised (hehe).

More studies are needed to identify the role of IGF-1, leptin and ghrelin as potential stimulators of bone growth and bone density.

Although bisphosphonates have been shown to significantly increase bone mineral density in young women with AN, there are significant side-effects that must be considered: bisphosphonates are tetragenic (that is, they can cause birth defects) and have a long half-life, meaning that they may be present even 2 years post discontinuation.

Hilariously (in my opinion), the idea of using cannabinoids to promote weight gain (munchies!) and thus improving bone health, was once a promising area of research. But alas, this didn’t pan out: one trails suggested that patients who ingested THC (the psychoactive ingredient in cannabis) had an increase in sleep disturbances (what??) and interpersonal sensitivity, but no effect weight gain. Similarly, another study showed no changes in weight but an improvement in depression and perfectionism scores.

So for now weight restoration and nutritional stabilization remain the key treatments in preventing bone density loss and reducing the risk of osteoporosis.


This review paper has some interesting points that I wasn’t completely aware of until now. Particularly that the standard dual-energy x-ray absorptiometry (DEXA) test “may not be able to distinguish bone that is small but o fnormal density from bone that is of low density.” This may potentially be a significant problem, particularly for short females such as myself. Moreover, as Teng points out, another pitfall of testing for bone density in premenopausal women is that it is possible they have not yet reached their peak bone mass.

Furthermore, Teng writes:

… density by itself is not a perfect tool for predicting who will or will not experience a fracture, particularly in premenopausal women. Most premenopausal women with low bone mineral density but no other risk factors for fracture such as previous fractures or glucocorticoid therapy are at very low short-term risk of fracture.

Regardless, or rather, despite these limitations, DEXA tests are still important tools to identify osteoporosis. More importantly, though, is tracking the changes in bone density over time – as these changes might provide a better understanding of the initial peak bone mass, the rate of increase or decrease in bone density and so on.

Despite its limitations, until newer risk assessment tools are available for this patient population, measuring bone mineral density is still recommended in addition to assessing clinical risk factors to diagnose osteoporosis. Also, changes in bone mineral density over time can help to assess risk and guide treatment.


Teng, K. (2011). Premenopausal osteoporosis, an overlooked consequence of anorexia nervosa. Cleveland Clinic Journal of Medicine, 78 (1), 50-8 PMID: 21199907

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Tetyana is the creator and manager of the blog. She has an Honours BSc in Neuroscience and an MSc in Medical Science. She can be reached at tetyana[at]scienceofeds[dot]org.


  1. I really appreciate this article. I’ve experienced a lot of confusion about osteoporosis, the contributing factors, and the possible treatments in conjunction with anorexia and you have described them clearly – thank you.

    I have very severe osteoporosis, was diagnosed a few years ago. Both of my femurs thinned to the point of cracking – stress fractures in a time when I was basically bedridden. It really does deteriorate fast – I had osteopenia in 2004 and full blown osteoporosis within a year after that.

    I’ve had about 4 or 5 periods in my life time (I’m 34) and have been severely underweight on an ongoing basis for about 15 years, having now been the highest continuous weight for that time – BMI xx [quite underweight] for 2 years now. I also had severe vit D deficiency after spending about 8 months with absolutely no sunlight because of being bedridden in a locked hospital ward. So I guess my poor bones didn’t really have a chance!

    I have been seeing an endocrinologist, and she put me on hormones – specifically (I think) progesterone and estrogen. I’ve taken calcium and vit D supplements for years now along with pretty much everything else. From what I can see, the hormones did nothing for me, and I’ve now gone off them due to them causing constipation and stomach issues.

    It took me a year of physiotherapy to improve core strength, posture, and to be able to start ballet again – more pilates than ballet – but what a gift to be able to. I didn’t think I’d ever dance again as a few years ago I was facing life in a wheelchair and in pain (I also at one stage couldn’t walk, and couldn’t sit or hold my head up alone, also have peripheral neuropathy which can be very painful). I’m so over the moon to be starting ballet again but terrified as I am feeling the same pains in my thighs as I did before they finally did scans to find the stress fractures.

    I know my current weight and nutrition won’t allow me to improve my bone density and that scares me most. Even knowing that I risk my mobility, I can’t overpower the Ed enough to do that much. But I’m working on it (my understanding is, until your body is no longer in starvation and is sufficiently nourished, it doesn’t have any reserves to direct towards rebuilding bone – it has to go to more essential functions first.)

    My main confusion is – I originally was told that while osteopenia can be reversed, you cannot reverse osteoporosis, only prevent it from further deteriorating. I’ve since been told by a few people that this is wrong, you can reverse osteoporosis too. Please can you clear this up for me if you can? Thank you 🙂 And thank you again for this article – it has really helped my understanding and in good timing since my next endocrinologist appointment is coming up this next week.

    (edited by Tetyana: x-ed out BMI values)

    • Fiona, thank you for your comment.

      I’m glad you have the strength to do ballet again! That’s great to hear. I can relate to the fear of not being able to do any exercise or physical activity.

      With regard to you question, I don’t have any medical qualifications whatsoever, so I don’t feel comfortable answering that question simply because I don’t know. I don’t know enough about the research into the treatment of bone density loss and how it differs for various populations. But what I do think is important to keep in mind is that the demarcation between osteopenia and osteoporosis is somewhat artificial. Osteopenia is simply -1.0 to -2.5 standard deviations below the normal (if it is reported a Z-score, it is age-matched control) and osteoporosis is -2.5 standard deviations below normal. This means that with osteoporosis, presumably, over 95% of people that age have higher bone mineral density, whereas that percentage is less for osteopenia. So, the difference between osteopenia and osteoporosis isn’t a concrete change in the severity of the bone loss, for example. Hopefully that makes sense. But yes, I have little knowledge of how reversible they are – I’m sure it depends on a lot of things, weight, age, genetics, peak bone bass, etc.. Do ask your endocrinologist and feel free to reply again with what he or she said!

      • Thank you. It’s really complicated isn’t it! And I am aware that the scores are calculated by age – so that complicates it all the more. I wish they would just use some static measure of how dense or not your bones actually were. I do remember back in about 2009 my doctor saying that my bones were worse than that of an 80 year old woman. But then again, I know plenty of 80 year olds without osteoporosis!

        I’m actually seeing the Endocrinologist on Monday afternoon – I’ll let you know. Thank you 🙂

        I really do think more needs to be done for people with eating disorders before they develop bone issues, and when they do. One thing my endo has said is that it’s more complicated to treat my osteop. than say, an elderly persons, because mine is through my lack of nutrition and hormones rather than the usual pattern with ageing and related factors.

        I also have heard of people with anorexia being denied preventative medications for it (if they even work) if they don’t eat/gain weight, which I think is like blackmail in a way. I know I was unable to eat better or gain weight if it meant preventing more damage to my bones – that’s what an ED is like. It’s unfair to do that to someone who is already probably trying so hard to eat better to stay alive and frightened at the level of irrationality they are hit with.

        • Fiona, I do think the following point you made is really important for people to know:

          “I really do think more needs to be done for people with eating disorders before they develop bone issues, and when they do. One thing my endo has said is that it’s more complicated to treat my osteop. than say, an elderly persons, because mine is through my lack of nutrition and hormones rather than the usual pattern with ageing and related factors.”

          It is important to realize that nutritional stabilization and weight restoration are at the cornerstone of preventing osteoporosis and perhaps improving bone health. There’s no way around it, as far as I know, for those with anorexia nervosa.

  2. Cannabis has been the single most positive influence in taking care of my body. I’d rather continue to be jobless for now if it means I can stop binging and purging every day.

    I wonder if I have osteoporosis sometimes because my body aches so terribly, and my joints even feel very weak. I finally began to exercise again. With not health insurance, there’s no way I can afford to check my bone density. But even when I had insurance, my doctor assured me that there was no reason to waste my time getting such a test. Really!?

    Another problem I am now dealing with is PAD (or so I assume). I have pain in my legs, and often in certain veins from the way it feels. I probably have some damaged or blocked vessels.

    I feel completely hopeless about treating any of these symptoms because the doctors have always seemed so incompetent and unconcerned.

    • Melissa: thank you for your comment.

      Out of curiosity, when you say cannabis has been the single most positive influence in taking care of your body, is that due to the anxiolytic and calming effects or to stimulate hunger?

      Sigh, I’m really sorry to hear about your negative experiences with doctors. It makes me so sad, frustrated and angry. I wish I could help somehow.

      I don’t know your situation, but I hope you can get health insurance in the future (? – the little that I know about the US healthcare system, is enough to make me want to pull all of my hair out) and perhaps meet some better doctors. They are not all unaware of mental health issues, and eating disorders specifically, but, as I’ve said previously, the lack of awareness in the profession overall is truly terrifying.

  3. This is such an important article. I suffered from a broken pelvis from simply running, two years ago. I am now dealing with chronic pain which has led to a whole bout of issues. I started training with a team for a half marathon to try out exercising the right way (I was a compulsive runner), and in the end, I broke my pelvis. This was two years AFTER I had completed inpatient residential treatment. The effects of your eating disorder stay with you for a very long time. I am still reaping the effects now with the chronic pain, and my life has changed a lot.

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