People with bipolar disorder who followed a ketogenic diet for at least six weeks found that their symptoms improved, a new study has found. While the study was small and preliminary, its findings open the door to a new treatment direction for the sometimes difficult-to-treat condition.
The brain benefits of a ketogenic or keto diet, which is high in fats, moderate in protein, and very low in carbohydrates, have been known for some time. Since the 1920s, the keto diet has been clinically proven to reduce seizures in individuals, especially children, with drug-resistant epilepsy.
A new pilot study, the first of its kind, led by researchers at the University of Edinburgh in the UK, found that eating a keto diet improved the symptoms of bipolar disorder (BD).
“These results add to a small but growing body of evidence suggesting that a ketogenic diet may be a safe and effective intervention for bipolar disorder, alongside existing medications,” said Dr Iain Campbell, study lead and Baszucki Group Research Fellow in Metabolic Psychiatry at the University’s Center for Clinical Brain Sciences. As someone who lives with BPD, Campbell follows a keto diet himself. “Poor metabolic health is a significant problem for people with bipolar disorder, so the study of metabolic treatment approaches is very much welcomed by the patient community.”
BD is a mental health condition characterized by extreme mood swings. Cycling between periods of mania or hypomania – high energy and excitement – and depression can have an enormous impact on a person’s daily life, work, and relationships. Further, studies have found that BD is associated with high rates of metabolic disorders – obesity, type 2 diabetes, cardiovascular disease – and the reduced life expectancy that accompanies them.
Drastically reducing carbohydrate intake and increasing fat intake induces ketosis. In this state, the liver converts fats into ketones, which the brain uses as an alternate fuel source to the glucose that would ordinarily come from the breakdown of carbs. Changing the body from a glucose-burning to a fat-burning state alters metabolism, reducing blood sugar and insulin levels and altering brain chemistry and function.
For the present study, the researchers worked from the hypothesis that epilepsy and BD share some common mechanisms, given that some antiseizure medications are useful in stabilizing mood and preventing extreme swings. They recruited 20 participants aged between 18 and 70 with diagnosed BD who had been euthymic – a stable mood state that is neither manic nor depressive – for at least three months. It's important to note that the study was a single-group, non-randomized, open interventional pilot study with no control group. This means it was a small, early-phase study in which all participants followed a ketogenic diet for six to eight weeks. It aimed to ascertain whether it was worth conducting a larger, more rigorous study.
Mental health symptoms – including affect (expression of emotion), depression, mania, quality of life, and work productivity – were measured at baseline and during follow-up. Participants also had blood taken and underwent magnetic resonance spectrometry (MRS), which, like MRI, uses a magnetic field and radio waves to analyze the chemical composition of the brain, providing information about metabolism, neurotransmitter levels, and cell function. They took their own glucose and ketone levels daily.
Overall, the researchers found that daily blood ketone levels were correlated with daily positive changes in mood, energy, impulsivity and anxiety but not with the speed of thought. Additionally, eating a ketogenic diet produced statistically significant positive metabolic changes. At baseline, 70.3% of participants were overweight or obese. Changing to the keto diet led to a decrease in mean body weight of 4.2 kg (9.3 lb) and a decrease in mean body mass index (BMI) by 1.5 kg/m2. Mean systolic blood pressure also decreased.
The MRS scans showed that the keto diet produced changes in excitatory neurotransmitters in brain regions associated with BD. Neurotransmitters are chemical messengers in the brain that help nerve cells (neurons) communicate. Excitatory neurotransmitters act like a gas pedal, exciting neurons, while inhibitory ones act like a brake.
“We observed markers of reduced excitotoxicity in two key brain areas: the anterior cingulate cortex and posterior cingulate cortex – both implicated in bipolar disorder,” Campbell said. “There is an urgent need for larger replication studies and carefully designed randomized clinical trials to build on these findings.”
Treatment of BD currently consists of medication, therapy, and lifestyle changes that can reduce the frequency and severity of mood episodes. As with other mental health conditions, for some people existing treatments aren’t effective. Which is why this study’s findings, albeit preliminary, are encouraging.
“The idea that a severe mental illness such as bipolar disorder may respond to a metabolic treatment such as the keto diet is challenging and exciting,” said senior author Professor Daniel (Danny) Smith, Chair of Psychiatry and Head of the Division of Psychiatry at the University of Edinburgh’s Center for Clinical Brain Sciences. Smith’s primary research and clinical focus is BD. “We are looking forward to carefully exploring links between metabolism and mental illness over the next few years.”
In early February 2025, UCLA Health announced it was about to begin a multi-site pilot study exploring the use of a ketogenic diet in teens and young adults with BD.
The study, which was funded by the Baszucki Group, was published in the journal BJPsych Open.
Sources: University of Edinburgh, Business Wire
