Ketogenic Diet for Schizophrenia: Clinical Implication

Zoltán Sarnyai; Ann-Katrin Kraeuter; Christopher M. Palmer


Curr Opin Psychiatry. 2019;32(5):394-401. 

In This Article

Ketogenic Diet in Patients With Schizophrenia: Review of Evidence From Case Studies

In 1965, a small uncontrolled clinical trial investigated 10 female patients hospitalized with chronic schizophrenia, who were treated with antipsychotics and electroconvulsive therapy, but continued to have symptoms.[60] These patients were placed on a ketogenic diet for 4 weeks. The researchers reported a significant decrease in symptoms after 2 weeks on the ketogenic diet. After the diet was discontinued, 7 of the 10 patients showed an increase in symptoms, but continued to experience better symptom control than at baseline.

In 2009, a 70-year-old woman with chronic schizophrenia since her teens was reported to have improved significantly after starting a ketogenic diet for weight loss.[61] The patient had daily auditory and visual hallucinations, and had been hospitalized repeatedly. Numerous medication trials failed to control her symptoms. The patient started the ketogenic diet for weight loss. Within 8 days of starting the diet, she reported no hallucinations and improved energy. After 1 year, she lost another 5 kg and remained free of hallucinations.

More rigorous and longer term case studies by one of us (C.P.) have been conducted. The summary of these six cases is detailed in Table 1.

In the 2017 study,[62] a male (Case #1) and a female (Case #2) patient with schizoaffective disorder were placed on a ketogenic diet for 1 year and 4 months, respectively. Both of them showed dramatic improvement in their Positive and Negative Syndrome Scale (PANSS) scores, and both also lost significant amounts of weight. Each patient had episodes of diet noncompliance, and symptoms returned within days. Symptoms again decreased when the diet was resumed. Both patients remained on antipsychotic medications during the ketogenic diet trial, but their treatment responses were significantly enhanced.

Two additional cases in Ecuador were male–female twins in their early 20s with schizophrenia that began at ages 18 and 14 years. They were placed on a therapeutic 3 : 1 ratio ketogenic diet for 6 weeks.[63] Assessments included PANSS scores, BMI, body composition (percentage of body fat), and liver function tests, among others. Both patients had compliance difficulties with the diet and neither achieved moderate or high levels of ketosis for prolonged periods. Nonetheless, after ~15 days of mild ketosis, PANSS scores decreased in both patients. Both patients lost weight and body fat.

Finally, two case reports published in 2019 assessed the long-term effects of the ketogenic diet in two women diagnosed with chronic schizophrenia.[64] The first case was a follow-up study of the woman described in the 2009 case report.[61] Twelve years later, she remained on the ketogenic diet, had lost a total of 150 pounds, reported complete remission of psychotic symptoms, and had stopped all psychotropic medications within 1 year of starting the diet. In addition, she no longer needed a guardian or PACT (Program of Assertive Community Treatment) team services, which had been in place for years, and she was living independently. The second case was a 39-year-old woman diagnosed with schizophrenia, chronic depression, anxiety and anorexia nervosa who had tried many medications over a 20-year period, including clozapine and Haldol-decanoate, but remained symptomatic. She started a ketogenic diet for gastrointestinal problems, and ultimately experienced complete remission from symptoms. She, too, was able to stop antipsychotic medications and remain free of psychotic symptoms for over 5 years. After recovering, she finished her graduate degree and now works full time. Both of these long-term cases suggest remission from chronic schizophrenia off of antipsychotic medications, with functional recovery.