The brain is the body’s most energy-intensive organ. Despite making up just 2 percent of the body’s mass, it consumes about 20 percent of its energy. Typically, the brain is mostly fueled by glucose that is produced by the breakdown of carbohydrates. But when there isn’t enough glucose to go around, the brain starts consuming fat-derived compounds called ketone bodies for fuel.

This shift, ketosis, is what happens when you follow a ketogenic diet, or keto diet, an eating regimen that is high in fat and low in carbs. Scientists have been studying how ketosis changes the brain since the early 1920s, when the diet was introduced as a therapy for treatment-resistant epilepsy in children. Some studies have also suggested it could help treat symptoms of Alzheimer’s disease.

And now results from several small trials bolster the case that the keto diet can help treat mental health conditions that include depression, bipolar disorder, schizophrenia and anorexia nervosa. The results are preliminary—randomized controlled trials are underway to better evaluate who might be helped by the diet and how much it might benefit them. But together, the findings support a theory of some mental illnesses as metabolic disorders, in which the brain’s ability to derive energy from its preferred sources becomes compromised.

Read more on Scientific American.