Diet and mental health: Can what you eat play a role?

Is there a relationship between your diet and mental health? It seems plausible that a person’s diet can play an important role. Certainly there is a link between physical and mental health.

There is good evidence that the 2 are linked. However, it’s problematic determining if one causes the other or they are indirectly linked. A recent review found that obese people, particularly those who also have metabolic dysfunction, are more likely to suffer mental illness.

One potential hypothesis on the link between diet and mental health is dietary inflammation. A recent paper discusses this idea. Interestingly, they found that many different diet interventions lead to improvements in mental illness.

Furthermore, they found that the key to these improvements was not about the specifics of the diet. Ultimately, it was more about whether the subjects lost weight or not.

For example, trials using the Mediterranean diet didn’t outperform other weight loss diets. This, despite the fact that it’s an anti-inflammatory diet.

This makes plenty of sense. To lose weight, you have to be in a calorie-restricted state. Calorie restriction decreases diet-induced inflammation, no matter how you do it. And having a little more around the midsection can amplify inflammation, as we discussed in this blog.

Diet and mental helath

A ketogenic diet and mental health

A recent paper looked at a ketogenic diet approach for mental health. They had very encouraging results, the people who stuck to the plan saw major improvements. Many decreased their medication use, despite having severe and persistent mental illness.

However, there was no control group making it difficult to rule out a placebo effect. Ultimately, the diet used in this trial was a very health ketogenic diet. The basic targets are:

  • Eating meat, seafoods, and eggs to satiety(15-20% protein)
  • 2 cups of raw greens per day
  • 1 cup of cooked non-starchy vegetables per day
  • A limit of 20g of carbs per day

So this was a fairly balanced ketogenic diet, and they were provided meals in an in-patient setting. On top of this, they were supplemented with fish oil, magnesium oxide, copper, as well as vitamins B1, B5, B6, B12, and C.

Though the diet did lead to major improvements, 27 of the 28 subjects lost weight. On average, they lost almost 11lbs. They also saw improvements in metabolic parameters as well.

So, at the end of the day, it’s difficult to determine if the improvements were specific to the diet or were simply an artifact of weight loss.

The Mediterranean diet and mental health

Theoretically speaking, a Mediterranean diet should improve mental health independently of weight loss. Many aspects of the diet are anti-inflammatory(Fish, vegetables, fiber, grains), so you’d expect to see additional benefit.

Three recent papers looked at the use of a Mediterranean diet to improve mental health. All 3 found the diet to improve mental health. Unfortunately, 2 of the 3(SMILES & HELFIMED) didn’t report BMI or weight loss in the subjects.

The third, the AMMEND trial, found improvements in with the Mediterranean diet over befriending therapy. So at the very least there’s a comparator group.

However, it’s locked behind a paywall and makes no mention of BMI or weight loss in the abstract. When that paper becomes available, we’ll take a gander at it and report back.

Even if there is an effect independent of weight loss, weight loss still could be the primary driver.


Though there is a connection between diet and mental health, it’s difficult to say one diet is better than the other. Ultimately, if the common link between the 2 is inflammation, the most important factor is likely going to be calorie restriction/weight loss.

While there are some substantial differences between a ketogenic and Mediterranean diet, both can lead to weight loss. Furthermore, the ketogenic diet used in the study discussed above has some common components with a Mediterranean diet:

  • Reduced or limited processed food intake
  • Higher Omega 3 intake(Via supplementation in the keto study)
  • Higher vegetable intake than most

Based on this information, a diet that supports mental health is likely a diet that is whole foods-based, contains a significant amount of vegetables, and leads to meaningful weight loss. This is great, because it means you have multiple options and can choose the diet that best fits your preferences and lifestyle.

However, it’s important to point out that there is zero evidence diet alone will have a substantial impact on mental illness. As such, it’s important to use all the tools you have at your disposal.

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