Evaluation of the Efficacy and Safety of Olanzapine for Anorexia Nervosa in Children and Adolescents

Inclusion Criteria: * Male or female between 11 and 17 (less than 18) at beginning of trial * Based on the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), patient fulfills criteria for diagnosis of Anorexia Nervosa (of which there are two types: restricting or binge-eating/purging) or Eating Disorder Not Otherwise Specified, with a weight of less than or equal to 85% of his or her ideal body weight, as can best be determined at the time of assessment * Treated by physician on the eating disorder team at the Children's Hospital of Eastern Ontario (CHEO) Exclusion Criteria: * Currently receiving treatment with any other antipsychotic medication, mood stabiliser, or stimulant * Known diagnosis of: diabetes, impaired glucose tolerance, hyperlipidemia, hepatic dysfunction, substance dependence, narrow angle glaucoma, paralytic ileus, or pancreatitis, or any other medical illness that would be considered to significantly impact treatment or recovery from the eating disorder * Any uncontrolled comorbid disease affecting any system including infectious, endocrine, renal, gastroenterologic, respiratory, cardiac, immunologic, or hematologic. Potential participants with controlled comorbidities in these areas may be invited to participate at the discretion of the primary investigator. * Experienced one or more seizures without clear and resolved etiology * Inability to comply with trial requirements including lack of comprehension of English * Pregnant or breast-feeding * High blood pressure * Known allergy or known sensitivity to products in olanzapine * Other unspecified reasons that, in the opinion of the investigator, amke the patient unsuitable for enrollment * Officially declared incapable of consenting to treatment under the Mental Health Act (Note: If a patient is involuntarily hospitalized, he or she can be invited to participate provided that he or she has not officially been deemed incapable of making treatment decision under the Mental Health Act) * Clinically judged to be at serious suicidal ris * More than 6 months have passed between the patient's initial eating disorder assessment and the time of study entry * Liver function test (ALT) \> 1.5 x upper limit of normal (ULN) * Positive pregnancy test * Electrocardiogram (ECG): QTc \> 450 msec or arrythmia other than sinus bradycardia; conduction abnormalities, prolonged QTc or other * LDL-C \> 4.9 mmol/L * Total cholesterol/HDL ratio \> 6 * Fasting glucose \> or equal to 6.1 mmol/L * Neutrophil count \< 0.5 x 10\^9/L * Prolactin level at assessment \> 200 ng/mL