The objective of this study is to determine the effects of the ketogenic diet on the frequency of non-epileptic seizures in patients with functional neurological symptoms disorder compared to a healthy diet.

This study consists of a open label randomized controlled clinical trial comprised of 20 patients with diagnosis of functional neurological symptom disorder with non epileptic seizures distributed in 2 arms of 10 patients each.

Patients will be randomly assigned to one of the groups. Both groups will be receiving treatment as usual (SSRI and/or psychotherapy). One group will be assigned a ketogenic diet while the other will be assigned a healthy diet, both supervised by a team of nutritionists. Patients will be evaluated every 2 weeks until reaching 6 weeks.

Inclusion Criteria:

• Patients who have a record at the institute and who have a diagnosis of a dissociative neurological symptom disorder with non-epileptic seizures with a certainty of at least clinically established who have a monthly seizure frequency greater than 3.
• Patients with the characteristics described above with comorbid epilepsy but who have not presented epileptic seizures in the last month.
• Patients with the aforementioned characteristics and who give their informed consent in writing to participate in the study.
• Patients who, once the diet has been explained to them, consider it feasible to implement it at least for the follow-up time.

Exclusion Criteria:

• Patients with metabolic or hemodynamic instability, liver failure, inability to tolerate the oral route, acute pancreatitis or pregnancy due to the possible teratogenic effect that has not yet been elucidated.
• Patients with metabolic disorders such as primary carnitine deficiency, palmitoyltransferase carnitine I or II deficiency, carnitine translocase deficiency, beta oxidation defects, pyruvate carboxylase deficiency, porphyria and other fatty acid transport and oxidation disorders.