How do eating disorders affect the skeletal system? A deep dive into bone health

October 22, 2025 •

4 min read

According to ACUTE, bone loss is a long-term complication of anorexia nervosa, with up to 90% of patients experiencing low bone mineral density. While often associated with anorexia, other eating disorders can also profoundly affect the skeletal system, disrupting crucial bone-building processes through malnutrition, hormonal imbalances, and other related behaviors. This damage can have lasting consequences, impacting skeletal strength and increasing the risk of painful fractures and osteoporosis.

Quick Summary

Eating disorders impair skeletal health by causing nutritional deficiencies, hormonal imbalances, and metabolic disruptions. This leads to decreased bone mineral density, increased fracture risk, and potential irreversible damage, particularly if onset occurs during critical growth phases.

Key Points

Low Bone Mineral Density: Eating disorders, especially anorexia, cause low bone mineral density (osteopenia) and can lead to severe osteoporosis.
Impaired Peak Bone Mass: Developing an eating disorder during adolescence, when bones should be strengthening, can prevent reaching peak bone mass, leading to a permanent deficit.
Hormonal Disruption: Nutritional deficiencies and low body weight cause hormonal imbalances, such as decreased estrogen and increased cortisol, which directly impair bone formation.
Increased Fracture Risk: Weakened bones due to low density and poor microarchitecture significantly increase the risk of fractures and stress fractures.
Purging and Bone Loss: Research shows that bone mineral density can be lower in individuals with normal-weight bulimia nervosa compared to healthy controls, indicating that purging behaviors are damaging independent of weight.
Recovery is Key for Improvement: While some bone loss may be permanent, weight restoration, nutritional rehabilitation, and therapeutic intervention are crucial to halting further damage and potentially improving bone density.

The Foundation of Bone Health: A Delicate Balance

Your bones are not static structures; they are living tissues constantly undergoing a process of remodeling, with old bone being broken down (resorption) and new bone being formed. This balance is crucial for maintaining bone mineral density (BMD) and strength throughout your life. A wide array of nutrients, including calcium, vitamin D, and protein, along with stable hormone levels, are essential for this delicate process. However, the restrictive eating, purging, and excessive exercise common with eating disorders can severely disrupt this balance, often with serious and long-lasting consequences for the skeletal system.

The Mechanisms Behind Skeletal Damage

Eating disorders attack the skeletal system through several interconnected pathways. Malnutrition is a primary driver, as the body is deprived of the essential building blocks needed for bone formation. Additionally, the stress of an eating disorder and its associated weight loss triggers a cascade of hormonal changes that actively undermine bone integrity.

Nutritional Deficiencies

Inadequate Calcium and Vitamin D Intake: Calcium is the primary mineral component of bone, and vitamin D is necessary for the body to absorb calcium effectively. Restrictive eating often means insufficient intake of calcium-rich foods like dairy, leafy greens, and fortified products. Low body fat also hinders the absorption of fat-soluble vitamin D.
Protein Deprivation: Protein is another vital nutrient for bone health, forming the organic matrix of bone tissue. Insufficient protein intake compromises the strength and structure of this matrix, making bones more brittle.

Hormonal Imbalances

Estrogen Deficiency: For women and girls, low body weight and insufficient body fat can lead to decreased estrogen production, causing menstrual cycles to stop (amenorrhea). Estrogen is critical for protecting and building bone mass, so its reduction significantly accelerates bone loss.
High Cortisol Levels: The physiological stress of malnutrition can cause elevated levels of cortisol, a hormone known to increase bone resorption (breakdown) and decrease bone formation.
Growth Hormone Suppression: In adolescents, low body weight can suppress the production of growth hormones, which are essential for achieving peak bone mass. If this disruption occurs during the crucial years of growth, it can result in a permanent bone density deficit.

Mechanical Stress and Weight-Bearing

Reduced Body Weight: Weight-bearing exercise puts healthy stress on bones, stimulating them to grow stronger and denser. However, the low body weight associated with restrictive eating disorders reduces the mechanical stress on bones, contributing to further bone loss.
Excessive Exercise: Conversely, excessive or compulsive exercise, particularly without proper nutrition, can also harm bones. Instead of building strength, it can increase stress fractures and exacerbate the underlying nutritional and hormonal issues.

Comparing the Skeletal Effects of Anorexia and Bulimia


Feature	Anorexia Nervosa	Bulimia Nervosa
Primary Cause	Severe caloric restriction and low body weight lead to widespread nutritional deficiencies and hormonal disruption, including amenorrhea.	Purging behaviors, including self-induced vomiting and laxative abuse, cause electrolyte imbalances, dehydration, and nutrient loss, and are also associated with reduced BMD, even in normal-weight individuals.
Bone Loss Severity	Often more severe due to prolonged malnutrition and very low body weight. Up to 90% of those with anorexia may have osteopenia or osteoporosis.	Can also cause significant bone loss, especially with a history of anorexia or prolonged purging. The bone-damaging effects are not solely dependent on being underweight.
Hormonal Impact	Profound hormonal changes, such as low estrogen and high cortisol, are common, directly impairing bone metabolism.	Hormonal disruptions may also occur, but are less consistently linked to amenorrhea, making the mechanisms more complex.
Peak Bone Mass	Adolescents with anorexia frequently fail to achieve optimal peak bone mass, setting them up for a lifetime of increased osteoporosis risk.	While possibly less pronounced than in anorexia, bulimia can still impact bone accrual during growth years, especially if there are periods of restriction.
Dental Damage	Indirectly affects dental health due to nutritional deficiencies.	Direct impact on teeth and jawbone health due to stomach acid exposure from frequent vomiting.

The Lifelong Impact and Potential for Recovery

The skeletal damage caused by eating disorders, particularly when they start during adolescence, can be persistent and difficult to reverse. The inability to reach peak bone mass leaves individuals with a permanent bone deficit, significantly raising their risk of osteoporosis and fractures later in life. This can lead to chronic pain, loss of stature, and reduced mobility.

However, it is never too late to address these issues. Recovery from an eating disorder is the most critical step toward healing the body, including the bones. A comprehensive recovery plan involves medical stabilization, nutritional rehabilitation, and therapeutic support. Nutritional therapy focuses on restoring a healthy body weight and ensuring an adequate intake of bone-supporting nutrients like calcium and vitamin D. Under a physician's guidance, weight-bearing exercise can help rebuild bone, but it must be done carefully to avoid overexertion or triggering compulsive behaviors. Specialized medications may also be used in severe cases to help rebuild lost bone.

Conclusion: A Silent but Serious Consequence

Eating disorders are complex mental health conditions with severe physical ramifications, and their impact on the skeletal system is one of the most critical and often hidden consequences. From the failure to achieve peak bone mass in adolescents to the development of osteoporosis in adults, the effects on bone density are profound and long-lasting. While some damage may be irreversible, sustained recovery that includes proper nutrition, weight restoration, and guided exercise can help mitigate further bone loss and even improve bone density over time. It is crucial to seek professional help to address the underlying eating disorder to protect your skeletal health and overall well-being. A silent disease, osteoporosis from eating disorders can dramatically reduce an individual's quality of life.

Frequently Asked Questions

While it can be difficult to fully reverse, especially if peak bone mass was not reached during adolescence, significant improvement is possible through weight restoration, proper nutrition, and medical treatment.

Anorexia causes bone loss through severe nutritional deficiencies (especially calcium and vitamin D), low body weight that reduces mechanical stress on bones, and hormonal imbalances like low estrogen and high cortisol.

Yes, research indicates that individuals with bulimia can have significantly lower bone mineral density than healthy individuals, even if they are at a normal body weight. This is linked to nutritional deficiencies and metabolic stress caused by purging behaviors.

The age of onset is a major risk factor. Developing an eating disorder during adolescence, when bones are rapidly gaining density, can be particularly damaging and lead to irreversible deficits in peak bone mass.

Calcium and vitamin D are critical for bone formation and absorption. Protein, magnesium, and vitamin K also play important roles. Nutritional therapy focuses on restoring these key nutrients through a balanced diet.

Under medical supervision, weight-bearing and resistance exercises like walking, jogging, dancing, and light weight-lifting can stimulate bone growth. Compulsive or excessive exercise should be avoided.

For women with anorexia, weight restoration is the most effective way to normalize hormones. Studies show that standard oral estrogen replacement is not effective in increasing bone density in adults with AN. However, newer research suggests specific physiological estrogen replacement regimens may help adolescents.