A 26-year-old man with tuberous sclerosis complex and multifocal seizures presented to the ketogenic diet clinic for management of his epilepsy. He had been started on the ketogenic diet at another institution at age 6 years, and his family had managed all nutritional aspects for the previous 10 years. Despite the lack of ongoing medical care, excellent seizure control and large urinary ketosis had been maintained, and side effects were limited only to poor growth. He remains on the diet to date, now for 21 years of continuous duration.