Before taking a closer look at the science, let’s look at anecdotes and case-reports since these are often the seeds for large medical trials.

What do medical case-reports say about ketogenic diets and schizophrenia?

In 2017 Christopher M. Palmer from from McLean Hospital at Harvard Medical School describes two case-studies, a 33 year old man and a 31 year old woman. They both found immense benefit upon adopting a ketogenic diet [1].

The man, who was obese at 322 lbs (146 kg), saw the following improvements after following a ketogenic diet consisting of “coffee with medium chain triglyceride (MCT) oil and butter (“bulletproof coffee”), eggs, meat, fish, poultry, spinach, kale, and olive oil” for 3 weeks.

15 lbs weight loss

dramatic reduction in auditory hallucinations

dramatic reduction in delusions

improvement in mood

improvement in energy

improvement in the ability to concentrate

After remaining on the diet for most of a year, he lost 104 lbs (47 kg) and his general functioning greatly improved. Importantly, he continued to experience a reduction in both positive and negative symptoms. The term positive symptoms refers to things schizophrenics have that non-schizophrenics don’t, like delusions and hallucinations. The term negative symptoms refers to a loss of function schizophrenics experience, like certain aspects of memory or cognition (thinking).

The man went off his ketogenic diet at least 5 times and every single time his positive and negative symptoms worsened substantially within a day or 2. They remained worse until he returned to ketosis (as measured by urine ketone strips and/or weight loss).

The woman, with a history of anorexia nervosa but no longer anorexic, saw the following improvements after following a ketogenic diet for 4 weeks consisting “mostly of coffee, eggs, poultry, and lettuce”

10 lbs (4.5 kg) weight loss

Delusions completely gone

Better mood

More energy

No longer anorexic at this point and having fat to lose, another 4 months on the diet led to 30 lbs (13.6 kg) of weight loss. A higher PANSS score means the schizophrenia is more severe, and hers dropped down from 107 to 70 - that’s excellent! When she went off the diet she suffered from severe paranoia and persecutory delusions. She returned to the diet but with no improvements. She then decided to fast for 3 days, which deepens the ketogenic state, and by day 3 her delusions completely resolved.

What’s particularly interesting with these case-reports is that they serve as a sort of ‘natural experiment’; go on the diet, things get better, go off the diet, and things get worse. This is repeatable, in the same person and in at least 2 different people. It increases our confidence that the diet (or the metabolic state of ketosis) may be responsible for the observed improvements.