Anorexia nervosa (AN) is accompanied by an increased frequency of pre-morbid anxiety. Anxiety disorders are associated with increased brain activity of catecholamines, especially noradrenaline. It has been hypothesized that noradrenergic dysregulation may be a major factor in the causation of AN. In this article, we explore this hypothesis and how it might account for the reduction of anxiety found in starvation, the increase in anxiety found with re-feeding, and thus the reinforcement of anxiety by re-feeding. We propose that alleviation of this dysregulation through the noradrenaline precursor (tyrosine) supplementation, leading to saturation of supply, may alleviate some of the pathological changes found in AN. We consider how the hypothesis might be investigated. The success of tyrosine supplementation would have important implications from theoretical, research and clinical perspectives.