Abstract: Ketogenic diets have been shown to play a role in some metabolic diseases and neurodegenerative diseases as a low-carbohydrate, high-fat diets supplemented with appropriate protein. Ketogenic diets have been proven effective, but the mechanisms of action are still unclear. Therefore, this paper summarizes the development of the ketogenic diet, its application in the treatment of metabolic diseases (type Ⅱ diabetes, obesity, non-alcoholic fatty liver disease, and gout), recommended diet plans and adverse reactions, and confirms that the ketogenic diet can be used as an adjunct therapy for metabolic diseases in terms of improving stress response and the intestinal microbiome. The classic ketogenic diet, medium-chain triglyceride, modified Atkins diet, and low glycemic index treatment are recommended as ketogenic diet programs. The adverse reactions of the ketogenic diet in metabolism, gastrointestinal tract, urinary system, and contraindications are summarized. This paper also summarizes the invention patents of ketogenic diet-related products, which paved the way and prospected for the subsequent product development and as an auxiliary treatment program.