Levels of IGF‐1 are low in anorexia nervosa31, 32 and are associated with low bone mass33; oral estrogen's dose‐dependent suppression of IGF‐134, 35 has been hypothesized to be an important contributor to the lack of benefit of oral estrogen for the treatment of low bone mass in anorexia nervosa.10 Our data suggest that in addition to suppression of bone resorption, IGF‐1 may also be a mediator of the beneficial effects of transdermal estrogen on BMD in this population. The gene discussed is IGF1; the disease is anorexia nervosa.