 Because the ketogenic diet alters the body 's metabolism , it is a first @-@ line therapy in children with certain congenital metabolic diseases such as pyruvate dehydrogenase ( E1 ) deficiency and glucose transporter 1 deficiency syndrome , which prevent the body from using carbohydrates as fuel , leading to a dependency on ketone bodies . The ketogenic diet is beneficial in treating the seizures and some other symptoms in these diseases and is an absolute indication . On the other hand , it is absolutely contraindicated in the treatment of other diseases such as pyruvate carboxylase deficiency , porphyria and other rare genetic disorders of fat metabolism . A person with a disorder of fatty acid oxidation is unable to metabolise fatty acids , which replace carbohydrates as the major energy source on the diet . On the ketogenic diet , their body would consume its own protein stores for fuel , leading to ketoacidosis , and eventually coma and death . 
