To initiate a low-carbohydrate, high-fat (LCHF) or ketogenic dietary (KD) intervention among a cohort of outpatients with either schizophrenia or bipolar illness who also have metabolic abnormalities, overweight/obesity, and/or are currently taking psychotropic medications experiencing metabolic side effects.

Adults with mental illness represent a high-risk, marginalized group in the current metabolic and obesity epidemic. Among US adults with severe mental illness, metabolic syndrome are highly prevalent conditions having severe consequences, with patients estimated to die on average 25 years earlier than the general population largely of premature cardiovascular disease. Many psychiatric medications, particularly neuroleptics and mood stabilizers, may, in addition, contribute to metabolic side effects and weight gain. Low-carbohydrate high-fat (LCHF) or ketogenic diets (KD) have been shown to reduce cardiovascular risk in those with insulin resistance. Recent findings support the idea that bipolar disorder, along with other psychiatric diseases schizophrenia, may have roots of metabolic dysfunction: cerebral glucose hypometabolism, oxidative stress, as well as mitochondrial and neurotransmitter dysfunction which has downstream effects on synapse connections. A KD diet provides alternative fuel to the brain aside from glucose and is believed to contain beneficial neuroprotective effects, including stabilization of brain networks, reduction of inflammation and oxidative stress. The purpose of this study is to evaluate both the metabolic and psychiatric outcomes with a KD diet in this psychiatric population.

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)