Ketogenic diet is comprised of foods high in fat, with adequate amount of proteins, and low in carbohydrates. With this type of diet, the body digests fats and store them into fatty acids and ketone bodies in the liver. And since carbohydrate sources are low there is not enough source of glucose, and therefore compels the body to utilize the stored ketone bodies as energy source.
This type of diet is recommended particularly for children with intractable epilepsy since it is meant to make the body burn fats rather than carbohydrates. Ketosis, which is a condition characterized by increased levels of ketone bodies in the body from ketone body metabolism, is found to lessen the frequency of epileptic seizures. Ketogenic diet also includes proteins but in amount enough to support growth and repair. It, therefore, recommends the consumption of fatty foods such as nuts, cream, and butter, and allows poultry, eggs, pork, beef, fish, and seafoods in the diet but restricts on carbohydrate-rich foods such as breads, pasta, starchy fruits and vegetables, and sugar. Although this diet is found to help curb the frequency of epileptic seizures, it may not be recommended to those who are at risk of kidney problems because it has been found to increase the risk of kidney stones.1
Apart from epilepsy, this diet may also be beneficial to patients with Parkinson's disease, migraine headaches, depression, autism, type 2 diabetes mellitus and polycystic ovary syndrome based on different studies reported. 2
1Levy RG, Cooper PN, Giri P. Ketogenic diet and other dietary treatments for epilepsy. Cochrane Database Syst Rev. 2012 Mar 14;3:CD001903. doi: 10.1002/14651858.CD001903.pub2. Source
2Hartman AL, Vining EP. Clinical aspects of the ketogenic diet. Epilepsia. 2007 Jan;48(1):31–42. doi:10.1111/j.1528-1167.2007.00914.x Source