Abstract: Ketogenic diet (KD) is a dietary model characterized by low carbohydrate and high fat, which has been used as an effective measure to treat epilepsy in a long history. With the continuous development of researches, KD has also been tentatively used in other fields of diseases, such as obesity, type 2 diabetes, metabolic-associated fatty liver disease, Alzheimer's syndrome and tumors. However, KD will lead to great clinical disputes because of imbalance in nutrient intake due to its unique dietary structure and some related adverse reactions during application. This study reviewed the advantages and disadvantages of KD for various diseases.