Inclusion Criteria:  Ages 13-25 (inclusive) Any sex Diagnoses of anorexia nervosa binge-purge subtype, bulimia nervosa, purging disorder, or atypical anorexia nervosa with bingeing or purging behaviors according to the Diagnostic and Statistical Manual version 5 diagnostic criteria Electing to participate in child or adult partial hospitalization program for eating disorder treatment at MSHMC  The diagnostic criteria for anorexia nervosa, binge-purge subtype, are:  A. Restriction of energy intake relative to requirements, leading to a significantly low body weight in the context of age, sex, developmental trajectory, and physical health. Significantly low weight is defined as a weight that is less than minimally normal or, for children and adolescents, less than minimally expected.  B. Intense fear of gaining weight or of becoming fat, or persistent behavior that interferes with weight gain, even though at a significantly low weight.  C. Disturbance in the way in which one's body weight or shape is experienced, undue influence of body weight or shape on self-evaluation, or persistent lack of recognition of the seriousness of the current low body weight D. During the last three months the individual has engaged in recurrent episodes of binge eating or purging behaviour (i.e. self-induced vomiting, or the misuse of laxatives, diuretics, or enemas).19 E. A diagnosis of atypical anorexia nervosa can be made when the body weight is normal or high If these patients engage in bingeing or purging behaviors as defined in anorexia nervosa, binge-purge subtype, they are eligible for inclusion in this study  The diagnostic criteria for bulimia nervosa are:  A. Recurrent episodes of binge eating. An episode of binge eating is characterized by  B. both:  i. Eating in a discrete period of time (e.g. within any 2 hour period), an amount of food that is definitely larger than what most individuals would eat in a similar period of time under similar circumstances; ii. A sense of lack of control over eating during the episodes (e.g. a feeling that one cannot stop eating or control what or how much one is eating.  C. Recurrent inappropriate compensatory behaviors to prevent weight gain, such as self-induced vomiting; misuse of laxatives, diuretics, or other medications; fasting; or excessive exercise.  D. The binge eating and inappropriate compensatory behaviors both occur, on average, at least once a week for 3 months.  E. Self-evaluation is unduly influenced by body shape and weight. F. The disturbance does not occur exclusively during episodes of anorexia nervosa.  • The diagnostic criteria for purging disorder are: recurrent purging behavior to influence weight or shape (e.g. self-induced vomiting; misuse of laxatives, diuretics, or other medications) in the absence of binge eating.  Exclusion Criteria:  Diagnosis of intellectual disability History of gender dysphoria History of known genetic or neurologic disease Need for treatment with opioid painkillers Weight <25kg Inability to swallow pills Lack of proficiency in written or spoken English Urine drug screen positive for opioids at enrollment Positive serum pregnancy test at enrollment Lactation Elevation of three times the upper limit of normal for age in either alanine aminotransferase (ALT) or asparagine aminotransferase (AST).High risk of suicide at enrollment on Columbia Suicide Severity Rating Scale (C-SSRS, for participants age 18-25) or Ask Suicide Screening Questions (ASQ, participants age 13 to 17)