The diet is very high in fat and low in carbohydrates. When fat is the primary source of calories, ketones are formed. The diet must be followed very strictly and requires a significant commitment to work effectively. Children on the diet often will not gain weight or grow much during the time the diet is in use. After that, however, growth is expected and should be carefully monitored.
Epilepsy is a general term for the tendency to have seizures. Epilepsy is usually diagnosed only after a person has had more than one seizure.
When identifiable, the causes of epilepsy usually involve some form of injury to the brain. For most people, though, epilepsy's causes aren't known.
The diet has been used mostly in children with difficult-to-control, generalized epilepsies -- such as those with the Lennox-Gastaut syndrome. Lennox-Gastaut is a generalized epilepsy which is characterized by drop attacks or tonic-clonic attacks (with violent, rhythmic convulsions) and often occurs in children with other neurological conditions, such as paralysis and mental retardation. It's often very resistant to treatment. In this group of individuals, the diet can be as successful as medications. Thus, it is most often recommended for children ages 2 through 10 or 12 who have been diagnosed with a generalized type of epilepsy, and who have failed to respond to a variety of drugs. Recent studies have shown that the diet may also be effective in those with partial seizures.
The diet is typically started with a period of fasting that lasts until the body produces a moderate to large amount of ketones. This initiation period usually takes place in the hospital, so that the individual can be monitored for potential side effects such as vomiting, low blood sugar, dehydration, and seizures. Medications may also be adjusted during this period to prevent sedation (the tranquilizing effect of medications), another common side effect.
A two-month trial period is suggested for deciding whether the diet is effective. If it is, it is typically continued for two years. During this time, individuals are often able to lessen the amount of medication they take for seizures. Many children seem happier and more alert on the diet, even before medication is significantly lessened.
People on a ketogenic diet should be monitored by a dietitian, nurse and doctor -- particularly a neurologist -- familiar with its use. Specialized epilepsy clinics are available to monitor a person on this diet.