Impact of a Ketogenic Diet on Metabolic and Psychiatric Health in Patients With Bipolar or Schizophrenia Illness

Inclusion Criteria:

1. Age 18-75 years old
2. Meet DSM V criteria for schizophrenia or bipolar disorder, any subtype, for \> 1 year and clinically stable (with no hospitalization for past 3 months)
3. Currently taking psychotropic medication and gained at least 5% weight since starting medication or have a BMI greater than or equal to 26 kg/m2 or presence of at least one metabolic abnormality (hypertriglyceridemia, insulin resistance, dyslipidemia, impaired glucose tolerance)
4. Willing to consent to all study procedures and attend follow-up appointments and motivated to follow the dietary program.
5. Sufficient control over their food intake to adhere to study diets.
6. Willingness to regularly monitor blood pressure, glucose, dietary intake, and body weight over the 4-month trial

Exclusion Criteria:

1. Any subject pregnant or nursing
2. Comorbidity of developmental delay
3. Active substance abuse with illicit drugs or alcohol
4. In a current severe mood or psychotic state when entering the study that would prohibit compliance with study visits or dietary program.
5. Anyone who has been hospitalized or taken clozapine over the past 3 months
6. Inability to complete baseline measurements
7. Severe renal or hepatic insufficiency
8. Cardiovascular dysfunction, including diagnosis of:

1. Congestive heart failure
2. Angina
3. Arrhythmias
4. Cardiomyopathy
5. Valvular heart disease
9. Any other medical condition that may make either diet dangerous as determined by the study medical team (e.g. anorexia nervosa)