The ketogenic diet is a formulated diet with a high proportion of fat and a low proportion of carbohydrates, with appropriate protein and other nutrients, that does not interfere with normal growth and development, while at the same time having a therapeutic effect on epilepsy, tumors and other diseases. This therapy has been used for decades to treat refractory epilepsy in children, and although its antiepileptic mechanism is still unclear, its effectiveness and safety are well established. Because the ketogenic diet is a therapy that replaces glucose with fat as a source of energy, any disease with impaired fatty acid transport and oxidation is a contraindication. 1. absolute contraindication; 2. carnosine deficiency; 3. carnosine palmitoyltransferase I or II deficiency; 4. carnosine transferase II deficiency; 5. beta-oxidation deficiency; 6. medium-chain acyl dehydrogenase deficiency; 7. long-chain acyl dehydrogenase deficiency; 8. short-chain acyl dehydrogenase deficiency; 9. long-chain 3-hydroxyl lipid acyl coenzyme deficiency; 10. medium-chain 3-hydroxyl lipid acyl coenzyme 11. pyruvate carboxylase deficiency; 12. porphyria. The above patients mainly present with developmental delay, cardiomyopathy, hypotonia, easy fatigue after exercise, and myoglobinuria. When patients have the above clinical manifestations, they should be screened for genetic metabolic diseases to exclude the above diseases.