“Keto diets should only be used under clinical supervision and only for brief periods,” Francine Blinten, R.D., a certified clinical nutritionist and public health consultant in Old Greenwich, Connecticut, told Healthline. “They have worked successfully on some cancer patients in conjunction with chemotherapy to shrink tumors and to reduce seizures among people suffering from epilepsy.”
Around this time, Bernarr Macfadden, an American exponent of physical culture, popularised the use of fasting to restore health. His disciple, the osteopathic physician Dr. Hugh William Conklin of Battle Creek, Michigan, began to treat his epilepsy patients by recommending fasting. Conklin conjectured that epileptic seizures were caused when a toxin, secreted from the Peyer's patches in the intestines, was discharged into the bloodstream. He recommended a fast lasting 18 to 25 days to allow this toxin to dissipate. Conklin probably treated hundreds of epilepsy patients with his "water diet" and boasted of a 90% cure rate in children, falling to 50% in adults. Later analysis of Conklin's case records showed 20% of his patients achieved freedom from seizures and 50% had some improvement.[10]

The day before admission to hospital, the proportion of carbohydrate in the diet may be decreased and the patient begins fasting after his or her evening meal.[19] On admission, only calorie- and caffeine-free fluids[37] are allowed until dinner, which consists of "eggnog"[Note 8] restricted to one-third of the typical calories for a meal. The following breakfast and lunch are similar, and on the second day, the "eggnog" dinner is increased to two-thirds of a typical meal's caloric content. By the third day, dinner contains the full calorie quota and is a standard ketogenic meal (not "eggnog"). After a ketogenic breakfast on the fourth day, the patient is discharged. Where possible, the patient's current medicines are changed to carbohydrate-free formulations.[19]
Anticonvulsants suppress epileptic seizures, but they neither cure nor prevent the development of seizure susceptibility. The development of epilepsy (epileptogenesis) is a process that is poorly understood. A few anticonvulsants (valproate, levetiracetam and benzodiazepines) have shown antiepileptogenic properties in animal models of epileptogenesis. However, no anticonvulsant has ever achieved this in a clinical trial in humans. The ketogenic diet has been found to have antiepileptogenic properties in rats.[56]
The word diet first appeared in English in the 13th century. Its original meaning was the same as in modern English, “habitually taken food and drink.” But diet was used in another sense too in the Middle and early modern English periods to mean “way of living.” This is, in fact, the original meaning of diet’s Greek ancestor diaita, which is derived from the verb diaitasthan, meaning “to lead one’s life.” In Greek, diaita, had already come to be used more specifically for a way of living prescribed by a physician, a diet, or other regimen.