Ketone bodies are the breakdown products of fat in the body, and large amounts of fat breakdown can lead to excess ketone bodies in the body and increased urinary ketones. The term ketogenic is commonly used to refer to the ketogenic state as well as the ketogenic diet. The ketogenic state is a state where carbohydrates are severely restricted and the ketogenic cycle is fully operational, while the ketogenic diet, a diet that intentionally allows the body to produce ketone bodies in an unconventional state, can be used for the treatment and control of patients with obesity, epilepsy, etc. The ketogenic state is a low-carbohydrate diet that promotes glycogen breakdown, which will feed the body through fat after glycogen is depleted, and fat cells gradually shrink, resulting in weight loss, which is the basic principle of the ketogenic diet. The ketogenic diet is a more specific diet, usually for the treatment of children with intractable epilepsy, obesity, and type 2 diabetes. The ketogenic diet consists mainly of a low-carbohydrate, moderate protein, high-fat diet. For patients who require a ketogenic diet, it is generally recommended that they do not eat staple foods and only eat side dishes, such as meat, fish and shellfish, vegetables, legumes, and fruits. In this state and diet structure, ketone bodies produced by fat metabolism supply energy to the brain, which can achieve anticonvulsant effects and is commonly used to treat refractory epilepsy in children. Due to the reduced intake of carbohydrates, the body produces less glucose and insulin, which is effective for type 2 diabetes, and patients with insulin resistance, such as those with polycystic ovary syndrome, people with three highs, and Alzheimer’s patients. However, it is not recommended that the general population lose weight in this way on their own, as there are certain contraindications to the ketogenic diet. People with kidney stones, liver disease, fat metabolism disorders, pregnant and lactating women, and people under stress may experience adverse reactions such as nausea and vomiting. For people with weight loss needs, they need to adopt a ketogenic diet under the guidance of a doctor.