Understanding risk factors: anorexia

The eating disorder, anorexia nervosa, is one of the risk factors associated with osteoporosis and broken bones. Here, Sarah Leyland, our Clinical Advisor, answers some of the key questions you might have about the links between osteoporosis and anorexia.

What do we know about the link between anorexia and loss of bone strength?

We know that bones need to be nurtured. Without adequate nutrients and hormones, they can become weaker, leading to an increased risk of broken bones. Anorexia increases the risk of osteoporosis because it results in low body weight, poorer nutrition to build and maintain bone strength and less pull through the muscles and bones to stimulate normal bone renewal.

Most importantly, anorexia reduces hormone levels. A very important indicator of low hormones, especially oestrogen in women and girls, is the stopping of periods or ‘amenorrhea.’ We know that the longer this continues, the greater the impact on bone strength.

Does anorexia cause osteoporosis?

When low bone density or broken bones are discovered in later life, it’s natural to want to look back for a cause. “Did anorexia in my earlier life cause my osteoporosis?” is a question that we’re asked on the Helpline. The answer isn’t straightforward or certain. Anorexia may be a cause, but it also may simply have contributed to developing osteoporosis.

Some people can feel guilt or responsibility for what’s happened, but the truth is, it’s usually very complex – a mixture of genes, environment, and possibly medical conditions too.

Do I need a bone density scan and bone-strengthening medication if I’ve had anorexia?

There are several challenges here if you are a younger person under the age of 50. Firstly, the majority of people with an eating disorder will have low bone density, so scans aren’t needed to confirm this. Secondly, a scan result in a younger person may not help with decisions about osteoporosis medication, which is the usual reason to have a scan.

Unfortunately, there aren’t medications that are proven or licensed to treat osteoporosis ‘caused’ by anorexia in younger people, and tackling the anorexia remains the very best approach.

Thirdly, although low bone density means a higher risk of a broken bone, the actual risk of this happening isn’t as high in a younger person, however low their bone density.

However, if the anorexia has continued for many years and bones have become very weak, a specialist may decide to prescribe a medication. This decision should be made by a specialist healthcare professional with experience in this area.

Hormones may be prescribed for younger people, including oestrogen for women and testosterone for men. Women may be offered Hormone Replacement Therapy (HRT) or a contraceptive pill containing oestrogen. There isn’t much research into this yet, but medications may be a worthwhile option.

If you are an older person, especially over the age of 50, then you’ll have a ‘fracture risk assessment’, and bone density scanning is usually part of this. Older people may be prescribed one of the standard medications, such as a bisphosphonate.

Should I take supplements?

Calcium, vitamin D or other supplements may be advised but, again, it’s essential to recognise that on their own, they won’t keep or make bones stronger. Focusing on the journey to recovery from the eating disorder is the best way to protect bone health.

What about exercise?

While exercise doesn’t usually cause a broken bone with osteoporosis and is generally very good for bone health, ensuring you are at a medically safe weight, and consuming sufficient calories to support your activity, is crucial. Over-exercise can go hand in hand with food restriction in anorexia, so tackling this as part of the recovery process is the priority for long-term bone health. Always speak to your healthcare professional to get the medical advice that’s right for you.

What should I do if I have anorexia and want to protect my bones?

It’s not an easy answer but tackling the root cause and taking the first step on the recovery journey from the eating disorder is the most important action you can take for your bones. It may be a medical specialist or an experienced counsellor or therapist. Your doctor or other healthcare professionals at your local GP surgery will be your first contact and there are organisations and specialist NHS teams to support you.

Information and support

For more information on anorexia as a risk factor associated with osteoporosis, please see our fact sheet.

For help and support about eating disorders, please contact your healthcare professional. You can also contact Beat, the UK’s eating disorder charity for information and guidance by visiting their website.