Eligibility Criteria:
Inclusion Criteria:
* Male or female between the ages of 18-35 with no history of any Axis-I diagnosis
* Does not meet criteria for substance abuse or dependence in the past six months
* Female subjects will use barrier-method, non-hormonal contraception
* Capacity to understand all the relevant risks and potential benefits of the study (informed consent)
* Must be able to speak and read English
Exclusion Criteria:
* Current or past Axis I psychiatric diagnosis, including alcohol or substance abuse or dependence (except nicotine or caffeine), but not including minor Axis I disorders (e.g. simple phobia)
* Lifetime use of psychotropic medications, including antipsychotics, antidepressants, mood stabilizers, and anxiolytics
* Presence or history of medical or neurological illness that, in the judgment of the investigator, could influence the results of the study
* Diagnosis of diabetes, hemoglobin A1C \> 6.5, hypertension, or dyslipidemias, or elevated random or fasting glucose, abnormal lipid levels, BP 130/85
* BMI 25 or \< 19, history of BMI \>35, and/or waist circumference \>35 inches for females, 40 inches for males
* Subjects who are pregnant or breast-feeding or planning to become pregnant during the study
* Acute suicidality
* Meets criteria for a Diagnostic and Statistical Manual, Version 4 (DSM-IV) defined eating disorder
* Use of, or clinical indication for, one or more of the following medications: lithium, anti-epileptic medication, steroids (oral or inhaled), stimulants, serotonin reuptake inhibitors, mirtazapine, tricyclic antidepressants, thyroid supplementation, sibutramine, metformin, thiazolidinediones, beta-blockers, clonidine, niacin
* Subjects who have had \>10% change in their body weight within the three months prior to enrollment
* HIV positive subjects
* Presence of mental retardation or pervasive developmental disorder
* History of recent (within 6 months) significant self-injurious behavior or violence
* Daily multivitamin or B-complex vitamin use
* A known history of dieting and difficulty with weight loss
* A strong family history of diabetes and/or heart disease
* History of congenital long QT syndrome or prolonged corrected QT interval (QTc) on screening EKG (\>450ms)
* Concomitant use of any medication that inhibits 2D6 or 3A4 metabolism
* Low serum potassium or magnesium