Inclusion Criteria:

1. Any gender
2. Any race,
3. Age range of 18-55.
4. Meet DSM-IV (APA, 1994) criteria for either schizophrenia or schizoaffective disorder.
5. Have a BMI greater than or equal to 27 with treated or untreated hyperlipidemia/ hypertriglyceridemia or a BMI greater than or equal to 30 regardless of concurrent risk factors
6. Be treated with the same SGA for at least 8 weeks and to have received a constant therapeutic dose for at least 30 days
7. Be clinically stable (for inpatients: at least one month post admission). Hyperlipidemia and hypertriglyceridemia are defined by ATP III guidelines such that borderline high and high will be considered as criteria for these disorders (ATP III 2001).

Exclusion Criteria:

1. Subjects with significant recent depressive symptoms will be excluded from the study, defined as any history of a suicide attempt or suicidal ideation or hospitalization for depressive symptoms within the last 6 months; or a high level of current depressive symptoms (Calgary Depression Scale of > 7) (Addington 1993, Kim et al 2006).
2. Subjects with intermittent alcohol or substance use will not be excluded unless they have met DSM-IV criteria for current alcohol or substance dependence within the last 6 months or DSM-IV criteria for alcohol or substance abuse within the last month.
3. Subjects with nicotine use or dependence will not be excluded.
4. Subjects with daily marijuana use will be excluded because of the possibility of physical dependence on cannabis. Those with with marijuana use no more than once a week will not be excluded because such subjects will not be physically dependent on marijuana and so not at risk for rimonabant-elicited acute cannabis withdrawal. Experimental studies of human cannabis physical dependence and withdrawal suggest that high-dose, multiple times a day administration is needed to produce physical dependence (Jones et al., 1976; Haney et al., 1999)
5. Subjects with a history of Crohn's Disease or Irritable Bowel Syndrome
6. Subjects with a organic brain disorder
7. A DSM-IV eating disorder
8. Subjects with mental retardation will be excluded to exclude subjects with cognitive impairment not related to schizophrenia. Mental retardation will be determined by chart review for a mental retardation diagnosis or a history of an IQ <70 and functional disability noted before the age of 18 (DSM-IV criteria for mental retardation).
9. Subjects with a medical condition, whose pathology or treatment could alter the presentation or treatment of schizophrenia or significantly increase the risk associated with the proposed treatment protocol will be excluded.
10. Subjects with a history of surgical procedures for weight loss .
11. Subjects who are currently in the process of trying to quit cigarette smoking will be excluded.
12. Female subjects of childbearing potential must agree to use medically accepted means of contraception. Pregnant and lactating female subjects will be excluded. People with a diagnosis of diabetes will only be included if their diabetes is currently treated and under control and have been on their current medication regimen for at 3 months.
13. People with a blood pressure reading of 165/95 or greater at baseline will be excluded from the study.
14. The concomitant use of medications that are known to alter weight or appetite, including anti-obesity drugs; corticosteroids; or nicotine substitutes will not be allowed (see Appendix 2: Medication Exclusion List). 15. Additionally, patients treated with a form of valproate will not be included in the study.

16. Subjects must be judged competent to participate in the informed consent process (by passing the ESC with a score of 10/12) and provide voluntary informed consent.