How eating disorders affect bone health

One of the lesser-known but serious consequences of eating disorders is the impact on bone health. Conditions like anorexia nervosa, bulimia, and other restrictive eating patterns can lead to significant bone density loss, increasing the risk of fractures, chronic pain, and long-term skeletal problems.

Understanding this connection is important because bone health complications can develop surprisingly early, can affect people at any age, and may not be fully reversible.

Why do eating disorders affect bones?

Bones are living tissue that constantly rebuilds itself through a process of breaking down old bone and forming new bone. This process depends on adequate nutrition, particularly calcium, vitamin D, phosphorus, and protein, as well as sufficient caloric intake and hormones including oestrogen and testosterone.

When a person restricts their food intake, purges regularly, or is malnourished for any reason, the body does not receive the raw materials it needs to maintain healthy bones. At the same time, the body may begin to break down existing bone tissue to access stored minerals for essential functions like keeping the heart beating.

Malnutrition also disrupts hormonal balance in ways that directly affect bone health. In women and girls, eating disorders commonly cause menstrual periods to stop (amenorrhoea) or become irregular. This leads to a significant drop in oestrogen, a hormone that plays a critical role in maintaining bone density. In men and boys, testosterone levels can similarly decline. These hormonal changes accelerate the rate of bone loss.

Osteoporosis and osteopenia

Osteoporosis is a condition where bones become weak, brittle, and more susceptible to fractures. People with eating disorders, particularly anorexia nervosa, can develop osteoporosis at a much younger age than the general population. Research has shown that measurable bone density loss can begin within the first year of an eating disorder, and can be clinically significant even in adolescents and young adults whose bones should still be growing and strengthening.

Osteopenia is a milder form of bone density loss that often precedes osteoporosis. It is even more common among people with eating disorders and represents a warning sign that, without intervention, further bone loss is likely.

The consequences of reduced bone density can include stress fractures (breaks caused by normal activity rather than significant trauma), chronic back pain due to vertebral compression fractures, loss of height over time, and long-term mobility problems. For young people, bone density loss during adolescence is particularly concerning because the teenage years are when the body normally builds peak bone mass, the foundation of skeletal health for the rest of life.

Which eating disorders affect bone health?

While anorexia nervosa is most strongly associated with bone density loss, other eating disorders can also affect bone health:

• Anorexia nervosa: The combination of caloric restriction, low body weight, and hormonal disruption makes anorexia the most significant risk factor for bone loss. Studies suggest that up to 90% of women with anorexia nervosa have reduced bone density.
• Bulimia nervosa: While the risk is generally lower than in anorexia, nutritional deficiencies from purging and periods of restriction can still contribute to bone weakness.
• OSFED and atypical presentations: People with atypical anorexia (meeting all criteria for anorexia except being underweight) can also experience significant bone density loss.
• Orthorexia: Severely restrictive diets that eliminate dairy, protein sources, or other nutrient-rich foods can lead to calcium and vitamin D deficiency and associated bone loss.

Can bone damage be reversed?

The good news is that with proper nutrition, weight restoration, and hormonal recovery, some bone density can be regained, particularly in younger people whose bones are still developing. Research shows that nutritional rehabilitation and weight restoration are the most effective interventions for improving bone density in people with eating disorders.

However, recovery is slow (it can take years for significant improvement), and may not be complete, especially if the eating disorder has been present for a long period or during critical growth years. This is one of the strongest arguments for early intervention. The sooner nutritional rehabilitation begins, the better the prospects for bone health recovery.

It is worth noting that, unlike in postmenopausal osteoporosis, bone-density medications (bisphosphonates) have not been shown to be effective for bone loss caused by eating disorders. Nutritional rehabilitation and normalisation of hormones remain the primary treatment.

How Wandi Nerida supports physical recovery

At Wandi Nerida, nutritional rehabilitation is a core component of the residential treatment program. Our dietitians work with each participant to restore adequate nutrition, with meal plans designed to meet individual needs. Our medical team monitors physical health throughout the stay, including tracking relevant markers of recovery.

The structured residential environment supports consistent nutrition over the full 60 to 90 day program, giving the body sustained time to begin the process of physical repair, including bone health recovery.

Where specific physical health concerns arise during treatment, including bone health, Wandi Nerida refers participants to external specialists as needed. In some cases, specialist appointments happen during the residential stay if the issue is urgent. In other cases, referrals are recommended for follow-up after treatment based on clinical need and the participant’s GP recommendation.

Throughout the program, physical health is closely monitored by nursing staff and GPs as needed. This includes daily observations (blood pressure and heart rate, checked between one and four times daily depending on clinical need), regular blood pathology (up to four times per week), blood sugar monitoring, and ECGs ranging from weekly to daily as needed. Each week, the GP reviews every participant’s physical observations, blood results, and any physical symptoms as part of a multidisciplinary team meeting, and sets a medical monitoring plan for the following week using a colour-coded system that reflects each participant’s level of medical stability.