We have explored the apparent similarity between patients with anorexia nervosa and a subgroup of male athletes designated as "obligatory runners." Case examples are provided from interviews with more than 60 marathon and trail runners. Obligatory runners resemble anorexic women in terms of family background; socioeconomic class; and such personality characteristics as inhibition of anger, extraordinarily high self-expectations, tolerance of physical discomfort, denial of potentially serious debility, and a tendency toward depression. Anorexic women and members of their families are often compulsively athletic, and obligatory runners may demonstrate a bizarre preoccupation with food and an unusual emphasis on lean body mass. We speculate that both phenomena could represent a partially successful--albeit dangerous--attempt to establish an identity. These preliminary observations will require further study for validation.