Patients with anorexia nervosa are known to have elevated basal growth hormone levels, which fail to suppress normally during glucose tolerance testing. We describe a case of probable anorexia nervosa initially diagnosed as acromegaly despite a low insulin-like growth factor-1 level and treated with transsphenoidal surgery based on a pituitary microadenoma on magnetic resonance imaging and a lack of suppression of growth hormone levels during glucose tolerance testing. This case highlights, firstly, that pituitary magnetic resonance imaging will suggest a pituitary adenoma in up to 10% of normal individuals. Secondly, that a diagnosis of acromegaly should be made on clinical features as well as growth hormone measurements.