How to Eat to Improve Depression? Nutritionist Offers Recommendations

A recent study explored whether ketogenic or Mediterranean diets are more effective in alleviating depression symptoms among obese adults. The research randomly assigned 64 obese participants to either a Mediterranean or ketogenic diet group, with both groups reducing their daily caloric intake by approximately 600 calories over three months. The Mediterranean diet group derived about 45% of its calories from carbohydrates, while the ketogenic group consumed only 5% from carbs, increasing fat and protein intake.

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In this group of obese adults, losing more weight does not necessarily mean a greater improvement in depression symptoms.

Both dietary interventions led to improvements in weight and depression symptoms. Notably, the ketogenic diet group experienced more significant weight loss. However, the Mediterranean diet group showed a greater reduction in depression symptoms. The study found no clear correlation between the amount of weight lost and the degree of improvement in depressive symptoms, suggesting that weight loss alone does not fully explain mood enhancement.

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The Mediterranean diet currently has more randomized controlled studies.

Nutritionist Tseng Chien-ming highlighted that while both diets improved mood, the Mediterranean diet's effect was more pronounced. He pointed out the study's limitations, including a reduced sample size for analysis (37 out of 64 participants) and incomplete depression scale data for many. Furthermore, all participants who completed the ketogenic diet were women, potentially skewing the results. The study participants also had mild depressive symptoms, not necessarily diagnosed clinical depression.

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The evidence for the Mediterranean diet cannot be said to be completely certain yet.

Tseng noted that existing research offers more consistent support for the Mediterranean diet's benefits on mood. Several randomized controlled trials, like the SMILES study (2017) and AMMEND study (2022), have indicated significant improvements in depressive symptoms and quality of life among participants following a Mediterranean diet. However, he cautioned that the overall evidence for the Mediterranean diet is still considered low to moderate in certainty due to variations in study designs, sample sizes, and statistical methods. Early research on ketogenic diets for depression is also emerging, with some studies showing potential short-term benefits, but these often lack control groups or have small sample sizes, making definitive conclusions difficult.

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The most accurate conclusion currently is that research on the Mediterranean diet for depression is more numerous, and the overall direction is more positive, but the certainty of the evidence is still limited.