Inclusion Criteria:  Must currently meet DSM-5 criteria for AN-R and AN Spectrum Disorders (i.e., Atypical AN) based on the Structured Clinical Interview for the DSM-5 (SCID-5-RV) Have a duration of illness ≥ 6 months Be medically stable as assessed by a comprehensive medical and behavioral evaluation conducted by a study physician  Exclusion Criteria:  Psychotic illness/other mental illness requiring inpatient hospitalization Current dependence on drugs or alcohol Physical conditions (e.g., diabetes mellitus, pregnancy) known to influence eating or weight or liver disease which may affect pharmacokinetics of the study drug Use of other psychoactive medications Significant changes in medication in past month Expression of acute suicidality Previous hypersensitivity reaction to Epidiolex or any of its constituents