Researchers at St. Michael’s Hospital in Toronto have found that a ketogenic diet — high in fats, moderate in protein, and very low in carbohydrates — may help reduce symptoms of depression in adults. Its impact on anxiety disorders, however, remains less clear. The findings were published in the journal Nutrients.
A ketogenic diet shifts the body to an alternative energy source: instead of glucose, the brain begins to use ketone bodies, which may influence mitochondrial function, oxidative stress, and inflammatory processes.
The scientists conducted a systematic review and meta-analysis of 50 studies from 15 countries, involving more than 41,000 participants. The sample included people with depressive disorders, bipolar disorder, and anxiety, as well as healthy volunteers. Mental health was assessed using standard scales such as PHQ-9 and GAD-7.
The analysis showed that participants who followed a ketogenic diet experienced a greater reduction in depressive symptoms compared to those who continued their usual eating patterns. The effect was particularly pronounced in studies that measured blood ketone levels — meaning the participants actually reached a state of ketosis. Strict carbohydrate restriction (around 10% of total calories) produced better results than less restrictive versions of the diet.
As for anxiety, the results were less convincing: randomized trials did not show a significant reduction in anxiety symptoms, although some improvements were reported in less rigorous studies.
The authors emphasize that a ketogenic diet is not a universal treatment for depression. They call for larger and longer-term studies to determine who may truly benefit from this diet and under what conditions, and to clarify how ketosis and mood improvement are connected.
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