They're likely referring to a ketogenic diet. They were quite common in the past before anticonvulsant meds were created, and are still used in intractable cases today, particularly in pediatric care. There's lots of information out there about their use in epilepsy.
Some to get you started:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2898565/
http://www.epilepsy.com/learn/treating-seizures-and-epilepsy...
http://www.mayoclinic.org/medical-professionals/clinical-upd...