Malaga researchers declare Mediterranean diet superior to keto for improving mood in obesity patients

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A pilot study led by Dr Francisco Tinahones shows traditional Mediterranean eating boosts beneficial gut microbes that protect the brain

José Antonio Sau

Friday, 13 February 2026, 13:43

A study led by a research team from Malaga has found that the Mediterranean diet is more effective than the keto diet in decreasing depression in people with obesity.

The team, led by Dr Francisco J. Tinahones and senior researcher Dr Virginia Mela, has explored the complex gut-brain axis to understand the how different diets affect emotional well-being.

Depression and obesity have a reciprocating relationship: an obese person can end up suffering from depression due to social stigma and biological changes, while depression can promote obesity through alterations in eating behaviour (binge eating, for example).

For three months, the researchers subjected 64 people to both diets: while the keto diet helped them lose weight more quickly, the Mediterranean diet significantly improved their depression scores.

The ketogenic diet is a very low-carbohydrate, moderate-protein, high-fat eating pattern that aims to put the body into ketosis - a state in which it uses fat as its main source of energy instead of glucose. By drastically reducing foods such as bread, pasta, rice and sugar, the liver produces ketone bodies that serve as fuel.

While the keto diet reduces impulsive eating, which may explain why patients manage to lose weight faster, the researchers have shown that the Mediterranean diet is more effective in decreasing the depression score.

Gut reaction

To further explore their findings, the team transplanted the participants' faecal microbiota into healthy mice. The mice that received the microbiota from the keto group developed anxiety-related behaviours, such as reduced exploration of open spaces and stereotypical stress movements.

This was linked to drastic changes in gut bacteria. While the Mediterranean diet increased beneficial bacteria, the ketogenic diet caused a decrease in protective bacteria, which produce short-chain fatty acids essential for regulating inflammation and protecting the brain.

Brain reaction

The study also analysed metabolites in the brains of the animal samples. In the keto microbiota receptors, the researchers detected an increase in substances that might serve as a compensatory mechanism to counteract the negative effects of depressive symptoms and neurotoxicity.

In conclusion, this pilot study underlines that obesity treatment should not focus solely on calories. As the authors point out, the findings emphasise the need to personalise dietary strategies that are sustainable in terms of long-term mental health.