The ketogenic diet was originally designed to simulate the effects of fasting. During fasting when a person has burned all their available carbohydrate, their body will switch to burning body fat to use as the next energy source.
Fasting has been used to help control seizures in individuals with epilepsy since biblical times. While fasting may help to control seizures, it cannot be used long term because the body will eventually run out of body fat stores, leading to starvation.
Unlike a person in starvation who will burn body fat for energy, a person on the ketogenic diet will burn dietary fat from the high fat foods they eat (e.g. butter, cream, oil), allowing them to remain in a fat-burning metabolic state over an extended period of time.
When the body is in a fat-burning metabolic state, this results in the production of ketone bodies, which accumulates in the blood. When ketone bodies accumulate in the blood to high enough levels, the body enters into a metabolic state of “ketosis”, which results from the shift from carbohydrate to fat metabolism as the main energy source. Ketone bodies are considered the hallmark of the ketogenic diet.
The high level of ketone bodies seen in a person on the ketogenic diet is associated with better seizure control; however the exact mechanism involved remains unknown.