Can eating disorders such as anorexia cause permanent bone damage?

More than 85% of women with anorexia have a bone density that is more than one standard deviation below the average for their age. Their risk of bone fractures is seven times higher than in people without anorexia. This is not a minor issue: it is one of the most serious physical complications of the condition.

The cause lies in a series of hormonal disruptions. Anorexia leads to the absence of menstruation, low growth factors, and elevated cortisol levels. Cortisol is a stress hormone that breaks down bone. All these factors together systematically hollow out bone structure.

In young people, the damage is especially severe. Bones grow most strongly during adolescence, and anorexia significantly slows that growth. As a result, teenagers with anorexia reach a lower peak bone strength than their peers, and that deficit is difficult to make up later in life.

After recovery, bone density partially improves, but full recovery does not always occur. Weight restoration and the return of menstruation are the best approaches for this. Transdermal oestrogen therapy can normalise bone development in adolescents, but does not fully close the gap. Oestrogen taken via the contraceptive pill is clearly less effective for this purpose. Bone medications such as bisphosphonates can modestly improve bone density in adult women, but are only used in severe cases because they can cause harm to an unborn child.

Even people who do not fall within the classic underweight range but have lost a significant amount of weight are at risk of similar physical complications. Bone damage is therefore not exclusively limited to the most recognisable presentation of anorexia.