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A ketogenic diet consisting of low-carb, high-fat foods may ease the symptoms of serious mental illness and reduce weight gain and other side effects from the drugs used to treat it, new research shows.
A clinical trial, led by researchers at Stanford Medicine, recruited 23 patients diagnosed with schizophrenia or bipolar disorder and instructed them to follow a diet consisting of 10 percent carbohydrates, 30 percent protein and about 60 percent fat.
The medications prescribed to treat serious mental illness can cause "major metabolic side effects," such as insulin resistance and weight gain, researchers say, and all of the patients studied suffered from at least one of these conditions.
After four months on a ketogenic diet, 79 percent of participants showed a "clinically meaningful improvement" in psychiatric symptoms.
The study was small and relatively short, so more research is needed to determine if dietary changes can have a meaningful, long-term impact on patients with schizophrenia or bipolar disorder. But the findings are part of a growing body of research suggesting a powerful link between brain health and diet. The ketogenic diet has also been studied in the treatment of Alzheimer’s disease and epilepsy.
Researchers theorize that the diet may improve psychiatric symptoms by correcting metabolic issues.
"The working theory is that we’re providing energy to the brain that circumvents these metabolic deficits," said Shebani Sethi, a clinical associate professor of psychiatry and behavioral sciences at Stanford Medicine and the lead author of the study.
Sethi said researchers know a ketogenic diet can benefit the brain but how much the diet may help schizophrenia or bipolar, in particular, "is really just emerging."
• The facts
• Patients were told to reduce their carbohydrate intake to 20 grams per day; to eat one cup of vegetables per day and two cups of salad per day; and to drink eight glasses of water a day. Sethi said she encouraged patients to use avocado, coconut and olive oils, and to not be afraid of butter. They were not told to count calories. Patients continued to take prescribed medications and were assigned a health coach.
• To determine how well they were sticking to the diet, patients were monitored with weekly blood tests. Fourteen of the participants stuck with the diet and six were "semi-adherent." One person was not adherent, and two more dropped out of the study.
• Participants improved an average of 31 percent on a psychiatric assessment of the severity of the mental illness, a rating called Clinical Global Impression scale.
• Those who stayed on the ketogenic diet lost - on average - 12 percent of their body weight, reduced their waist circumference by 13 percent and their visceral adipose tissue (the fat around organs) dropped by 36 percent.
• Before starting the diet, 29 percent of the participants had at least three of the five markers for metabolic syndrome - a cluster of conditions that together raise the risk for heart disease, diabetes and other chronic diseases. After four months on the diet, none of the participants had metabolic syndrome.
• What other experts say
Uma Naidoo, a nutritional psychiatrist and author of "This is Your Brain on Food," said the findings of the clinical trial are "promising," but it’s also a small cohort of participants and the results need to be replicated in larger studies.
"It’s not a one-size-fits-all method. The fact that it worked in a small clinical trial for these individuals, based on what seems to be some well-thought-out science, doesn’t mean it will work for everyone," Naidoo said. "Nutritional psychiatry is an emerging field that people should be paying attention to but that doesn’t mean that they shouldn’t take medication if their doctor is suggesting it."
Drew Ramsey, a nutritional psychiatrist and author of "Eat to Beat Depression and Anxiety," said in an email that the pilot study is a "well-documented, thoughtful trial" but there’s no control group, or randomization, "which needs to temper our enthusiasm."
"The big questions around keto and patients with severe mental illness are around compliance, sustainability and potential negative metabolic effects," Ramsey wrote in an email.
• Background
A high-fat diet causes your body to burn fat for energy, instead of glucose. This process leads to the production of ketones, an acid produced when the body breaks down fat. Ketones don’t rely on the same "metabolic machinery" the body uses to turn glucose into energy, Sethi said.
Ketogenic - or keto - diets were used by physicians more than a century ago to treat epilepsy. The restrictive diet, which avoids bread, pasta, and starchy fruits and vegetables, has reached broader appeal in the last decade, especially on TikTok and Instagram, as proponents claim it can lead to weight loss.
But some experts say there is widespread misinformation about the diet’s benefits, and the American H
eart Association said the diet can often cause an increase in LDL cholesterol levels. Common side effects of switching to a ketogenic diet include headaches, fatigue and constipation. Researchers say some participants experienced these side effects in the first three weeks on the diet.
Research regarding how a ketogenic diet may affect psychiatric illnesses is "in its early stages," researchers say. The keto diet has already been studied for the treatment of obesity, Type 2 diabetes and epilepsy. According to the researchers who conducted the clinical trial, "numerous studies" have shown keto can treat epilepsy - especially in children, with some patients "achieving long-term seizure freedom."
"The way that we think it works in reducing seizures in the brain is that it stabilizes neural membranes and it’s reducing inflammation," Sethi said. "It’s also providing an alternative fuel to glucose because we either burn glucose or we burn ketones for energy."
Funding for the pilot study came from the Baszucki Group Research Fund (co-founded by the founder of Roblox, David Baszucki, and his wife, Jan Ellison Baszucki), the Kuen Lau Fund and the Obesity Treatment Foundation.
• What's next
The next step is conducting randomized controlled trials with more participants, Sethi said. Some randomized trials are already underway, including one at the University of California at San Francisco.
Sethi said she’s also interested in studying whether the keto diet could have an affect on those with bulimia or a binge-eating disorder.
Sethi said a ketogenic diet is "not for everyone" and a person should only start a ketogenic diet "under the monitoring of a physician."
"I have a tailored approach to who I would prescribe it to and for what reasons," she said.
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