This open-label pilot study seeks to investigate the safety and efficacy of psilocybin in
persons with chronic anorexia nervosa (AN). Psilocybin has previously been demonstrated to
decrease depression and anxiety and increase long-term positive behavior change in other
populations. The investigators seek to determine whether similar changes can be safely
produced in people with AN when psilocybin is administered in a supportive setting with close
follow-up. The investigators' primary hypotheses are that psilocybin is safe to administer in
people with AN, that it will reduce measures of anxiety and depression, and that it will lead
to increased quality of life. The investigators will also assess a number of exploratory
measures related to eating disorder pathophysiology.