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A recent study published in the Schizophrenia Bulletin suggests that a ketogenic diet provides metabolic and psychiatric benefits for individuals diagnosed with schizophrenia or bipolar disorder. The research indicates that shifting the brain’s primary fuel source from carbohydrates to fat derivatives called ketones tends to improve markers of blood sugar regulation. The findings also provide evidence that adopting this diet is associated with reduced symptoms of depression and psychosis over time.
People diagnosed with psychotic disorders frequently experience impaired cognitive function and disrupted daily living. The psychiatric medications typically prescribed to manage these conditions tend to induce high rates of metabolic dysfunction. These physical side effects often include elevated blood sugar, weight gain, and an increased risk of developing metabolic syndrome.
Metabolic syndrome involves a cluster of risk factors, such as high blood pressure and elevated fasting glucose, which correlate with shorter lifespans and more severe psychiatric symptoms. Diet plays a large role in the onset of this syndrome, and individuals with schizophrenia often face lifestyle challenges that make traditional nutritional management difficult.
The ketogenic diet is a nutritional approach composed of roughly 70 percent fat, 20 percent protein, and 10 percent carbohydrates. By severely restricting carbohydrate intake, the diet forces the body to break down fat into molecules known as ketone bodies. These ketone bodies provide an alternative energy source for cells.
Laboratory studies suggest that ketone metabolism yields more energy than glucose metabolism, which might help counteract the dysfunctional glucose processing often observed in the brains of individuals with schizophrenia. Previous case reports and uncontrolled studies provide evidence that the ketogenic diet can alleviate metabolic syndrome and psychiatric symptoms in various mental health conditions.
“A number of pilot studies have signaled the promise of a ketogenic diet as a treatment of serious mental health, but to attribute these positive effects to the diet rather than any other factors we still need randomized controlled trials (RCTs) comparing the ketogenic diet to another diet,” said Judith M. Ford, a professor in the Department of Psychiatry and Behavioral Sciences at the University of California, San Francisco. “Our study was a first attempt to directly make this comparison in participants with schizophrenia-spectrum or bipolar-1 disorder.”
The researchers recruited adult participants who met the diagnostic criteria for schizophrenia, schizoaffective disorder, or bipolar disorder with psychotic features. The research began with 58 participants who were randomly assigned to either a ketogenic diet group or a diet-as-usual control group for a one-month period.
Participants in the ketogenic diet group received 18 microwavable meals each week from a contracted delivery service. They were instructed to consume at least two provided meals a day and keep their overall carbohydrate intake below 10 percent. The diet-as-usual group was asked to continue their typical eating habits and did not receive prepared meals. Both groups received weekly check-in calls from a licensed dietitian.
The researchers measured several physiological variables, including body weight, insulin resistance, and hemoglobin A1c, which is a protein that reflects average blood sugar levels over several months. The authors also measured cognitive performance and psychiatric symptoms, such as depression and the positive and negative symptoms of psychosis. The analytical models adjusted for participants’ initial baseline scores to ensure that any observed changes were not due to preexisting differences between the groups.
At the end of the one-month trial, individuals in the ketogenic diet group demonstrated metabolic improvements compared to those eating their usual diet. Based on objective blood tests, the ketogenic group successfully reached and maintained standard nutritional ketosis. “We also showed that this diet is highly feasible in this population, with 83 percent of daily-tested participants maintaining ketosis in the one-month RCT portion of the study,” Ford noted.
Compared to the diet-as-usual group, participants on the ketogenic diet experienced a relative decrease in body mass index and lower levels of both hemoglobin A1c and insulin resistance. For instance, the ketogenic diet participants saw a moderate absolute reduction in their body weight and blood sugar markers, whereas the control group experienced nearly no change. Cognitive performance and symptoms of psychosis did not differ between the two groups at the end of the first month.
Partway through the trial, the researchers secured funding to offer an extended four-month ketogenic diet phase to all participants. A total of 25 individuals completed this extended dietary protocol. “Adherence to the diet was also high in this extension period (94 percent), with no reports of significant side effects from the diet,” Ford explained.
“I don’t know if this surprised us, but we were really encouraged to see the high feasibility of this diet in an outpatient population of patients with schizophrenia-spectrum or bipolar-1 disorder,” Ford said. “A common assumption we hear is that the diet must be too difficult for participants with severe mental illness to adhere to, but 25 of the participants opted to continue on the diet beyond the one-month RCT.”
This level of adherence suggests that lifestyle interventions are possible for this population when adequate resources are provided. “This choice to extend demonstrates the viability of this diet as a long-term intervention, along with support from our team, which included providing them with 18 microwavable ketogenic meals per week via a specialized delivery service, an initial coaching session, and support from a dietitian or research assistant,” Ford added.
Because there was no active control group for this extension phase, the researchers assessed changes by comparing the participants’ metabolic and psychiatric measurements at the four-month mark directly against their initial baseline scores. “The most notable effects in this study were the significant metabolic improvements in the ketogenic diet group compared with the control group in the RCT part of the trial,” Ford said.
After four months on the ketogenic diet, participants demonstrated enhanced cognitive performance and reductions in both the positive and negative symptoms of schizophrenia. They also experienced a marked reduction in depressive symptoms. Measurements of body mass index and hemoglobin A1c remained lower than their initial baseline levels.
“While we also saw significant improvements in depression, schizophrenia symptoms, and cognitive performance after four months on the ketogenic diet, we can’t attribute those effects to the specific diet, as it was offered to all participants at this stage,” Ford cautioned.
Readers might wonder why cognitive benefits did not appear earlier in the trial. Ford clarified this timeline, referencing similar clinical observations from other recent diet studies. “We weren’t able to see neuropsychiatric or cognitive benefits of the ketogenic diet after only one month on the diet, indicating that participants may need a longer time on the ketogenic diet for those benefits to emerge,” Ford said. “This is consistent with other similarly-sized single-arm pilot studies such as Volek et al. (2025), Campbell et al. (2025), and Sethi et al. (2024).”
To explore the mechanics behind these improvements, the authors conducted statistical tests to see if the clinical gains were tied to the presence of ketones or simply to weight loss. They found that higher levels of blood ketones strongly correlated with greater reductions in hemoglobin A1c and depressive symptoms.
Changes in body weight did not correlate with these specific metabolic or psychiatric improvements. “Also, we wondered throughout the trial if benefits would be due solely to weight loss,” Ford said. “We were gratified to find that the improvement in depressive symptoms and metabolic health was not related to weight loss but to ketone levels, even in the one-month RCT.”
The study design involves a few elements that could influence how the outcomes are interpreted. “There are a couple of caveats,” Ford noted. “First, it’s important to note that we did not have a control group for the four-month extension of the study, meaning all significant improvements we observed in neuropsychiatric symptoms and cognition were in a single-arm design. This indicates the need for longer-term RCTs to explore these effects.”
Because the control group did not receive catered meals, the ketogenic diet group had an inherent advantage in accessing free, easily prepared food that included fresh vegetables and proteins. “Second, we only provided meals to the ketogenic diet group, while the diet-as-usual group followed their regular diet,” Ford said. “As a result, we can’t rule out that meal provision itself contributed to some of the observed benefits. We recommend that future studies address this variable in their design.”
The study relied on a relatively small sample size, which prevented the authors from testing complex statistical models or separating the outcomes by specific psychiatric diagnoses. Certain physiological measurements were not tracked during the trial. The blood tests did not assess markers like cholesterol or detailed electrolyte balances.
These omitted measures are important for evaluating long-term cardiovascular health and the risk of developing kidney stones on a high-fat diet. The research team also did not track adjustments to participants’ psychiatric medications throughout the study.
Future research could benefit from longer monitoring periods and larger sample sizes to clarify how dietary interventions interact with standard psychiatric treatments.
“Our results are really promising, indicating that a ketogenic diet is feasible and safe in patients with serious mental illness, and our single-arm extension findings also indicate that the ketogenic diet may be beneficial for alleviating depression and schizophrenia symptoms,” Ford concluded. “We hope to see more funding being made available for RCTs that follow larger groups of patients for longer periods of time to establish whether the ketogenic diet is an effective treatment strategy for serious mental illness.”
The study, “Metabolic Improvements with a Ketogenic Diet Correlate with Symptom Improvement in Psychosis: A Randomized Controlled Trial,” was authored by Samantha V. Abram, Juliette M. Kyner, An Vu, Zanib Naeem, Shebani Sethi, Michael S. Jacob, Susanna L. Fryer, Daniel H. Mathalon, and Judith M. Ford.