Diet is increasingly discussed as a potential tool for supporting mental health. A new randomized clinical trial suggests that a ketogenic diet may offer modest short-term benefits for people with treatment-resistant depression, though researchers stress that the findings are preliminary and should not be overinterpreted.
The study, published in JAMA Psychiatry, compared a ketogenic diet with a carefully matched control diet over six weeks. Participants had treatment-resistant depression, meaning their symptoms had not responded adequately to standard treatments.
A ketogenic diet is a very low-carbohydrate, high-fat eating pattern that substantially reduces carbohydrate intake. This shift is intended to move the body toward using ketones rather than glucose as its primary fuel source.
At the end of the trial, participants following the ketogenic diet showed greater improvement in depressive symptoms than those in the control group. However, the average difference between groups was modest, and the effect was not consistently observed across secondary outcome measures. The authors note that while the results were statistically significant for the primary outcome, the clinical relevance remains uncertain.
Unlike observational studies that examine dietary patterns in large populations, this trial tested a specific dietary intervention under controlled conditions. Both diets were designed to be nutritionally comparable, helping to isolate the effects of macronutrient composition rather than calorie intake or overall diet quality.
Even so, the researchers emphasize important limitations. The trial was relatively short, followed participants for only six weeks and included a narrowly defined clinical population. The findings do not indicate whether benefits would persist over longer periods or apply to people with milder depression or to the general population.
The ketogenic diet has been proposed as a way to influence brain metabolism and inflammation. While these mechanisms are biologically plausible, the study does not establish how or why the observed changes occurred. Nor does it show that dietary changes can replace established treatments such as medication or psychotherapy.
In an editor’s note accompanying the publication, the journal underscored the need for caution in interpreting the results. Modest effect sizes and the absence of consistent secondary findings suggest that the diet’s role, if any, is likely to be limited and context-dependent.
The study arrives amid growing public interest in dietary approaches to mental health, particularly highly structured diets promoted online. Experts caution that restrictive diets can be difficult to maintain and may not be appropriate for everyone, especially without clinical supervision.
Taken together, the findings suggest that diet may play a role in mental health for some individuals, but they also reinforce how complex that relationship is. Larger, longer-term trials are needed to determine whether ketogenic diets provide meaningful benefits, who might benefit most and how dietary interventions could be integrated safely alongside standard mental health care.
This trial was funded by the National Institute for Health and Care Research Oxford Health Biomedical Research Centre. Dr. Min Gao and Dr. Megan Kirk were funded by the NIHR Oxford Health Biomedical Research Centre and the NIHR Oxford and Thames Valley Applied Research Centre. Dr. Susan Jebb and Dr. Paul Aveyard were supported by the NIHR Oxford Biomedical Research Centre and the NIHR Oxford and Thames Valley Applied Research Centre. Dr. Michael Browning was supported by the Office for Life Sciences and the NIHR Mental Health Translational Research Collaboration, hosted by the NIHR Oxford Health Biomedical Research Centre.