Ketogenic diet (KD) is a high-fat, moderate protein and low-carbohydrate diet. Under normal circumstances, the body’s energy supply comes mainly from the three major nutrients of carbohydrates (sugars), proteins and fats in food, of which carbohydrates supply about 50% to 60% of the total energy. kD converts the body’s energy supply to mainly fat (90%), 10% from protein and carbohydrates, and calories are generally limited to 75% of the recommended standard for the same age group. It directly causes systemic changes such as elevated ketone bodies, fatty acids and reduced glycolysis. KD has been used for the treatment of refractory epilepsy (RE) for nearly 100 years, but its clinical use has gradually decreased due to the introduction of new antiepileptic drugs (AEDs). In recent years, due to the gradual increase of RE patients and adverse drug reactions, KD has started to receive wide attention from clinicians again. The clinical use of KD for the treatment of pediatric RE has become more mature, but its use for the treatment of adult RE is still relatively rare. With the emergence of modified KD, adult RE also began to apply this therapy. Domestic and foreign reports have confirmed that KD has certain efficacy on adult RE and is not correlated with ketone body level. Classification of KD 1. Classical KD: The weight ratio of fat to carbohydrate and protein (i.e. ketogenic ratio) is 4:1, i.e. the diet contains 3 grams of fat for every 1 gram of protein and carbohydrate, with each gram of fat providing 9 kilocalories (Kcal) and each gram of protein and carbohydrate providing only 4 Kcal, mainly used in children. 3:1 formula is used in infants The fat component is mainly long-chain triglyceride (LCT). 2, medium-chain triglyceride (MCT) diet: fat is mainly MCT (60%), MCT is more likely to produce ketone bodies, once used in children and adolescents, but for some children can produce gastrointestinal irritation and vomiting, diarrhea, intestinal cramps, and then there is a modified MCT, 30% of energy from MCT, 40% from 3, modified Atkins diet (MAD): the weight ratio of fat to carbohydrate and protein is 1~2:1, the daily carbohydrate intake is 10~30g, starting with less than 10g/d for children and 15g/d for adults, and then gradually increasing the amount of carbohydrate every month, without strictly limiting the amount of calories, protein and It is easy for patients to accept, and it is more advantageous for adolescent and adult patients to use it. 4.Low glycemic index treatment (LGIT): The ketogenic ratio is 0.6:1, which mainly depends on the intake of foods with glycemic index (GI) lower than 50, such as lentils, whole grain bread, processed oatmeal, olive oil, grapefruit, cucumber, etc. The carbohydrate intake can be 10%~15%. In recent years, only a few medical institutions at home and abroad have conducted clinical studies on the application of KD to adult RE, and it has been found that KD is equally effective when applied to adult RE and pediatric RE, and adults can tolerate KD as well, especially MAD. The efficacy was slightly better for adolescent RE than for adult RE, and differences in seizure syndrome or seizure type did not significantly affect KD efficacy. How to start KD KD starts with about 1 week of hospitalization and observation under physician supervision. For adult RE patients with well-tolerated MAD, the initiation process of changing diet therapy is introduced here as an example of MAD: the patient starts to reduce carbohydrate intake on the day of admission, preferably without intake, while improving liver and kidney function, blood glucose, lipids, electrolytes, blood and urine stool routine, trace elements, parathyroid hormone, immunoglobulin and complement, cardiac enzyme profile, blood tandem mass spectrometry, abdominal ultrasound (bilateral kidney, Ureter, bladder, liver, gallbladder, pancreas and spleen), ECG and other examinations. On the second day of hospitalization, after the results of the tests are basically available, we have a general understanding of the patient’s general condition, exclude contraindications, and start fasting that night (children often need to fast for 12 to 48 hours when they start KD to quickly reach a state of ketosis) and can drink. On the night of fasting, monitor blood glucose and blood ketones every 6 hours starting from 21:00. Clinical observation shows that blood ketones greater than 0.5mmol/L in adults can start to show effect (children require blood ketones greater than 2mmol/L), if there is serious hypoglycemia, timely treatment is needed. On the 3rd day, the formal feeding of MAD starts, and the caloric calorie on that day is 1/3 of the total caloric calorie, on the 4th day is 2/3 of the total caloric calorie, and on the 5th day the full amount starts, and the patient can be discharged after no obvious gastrointestinal reaction, tolerating MAD, stable blood glucose and blood ketone, and learning the calculation method of MAD until the 7th day. Carbohydrates were limited to 15g/day for the first 1 month and could be gradually increased to 20~30g/day after 1 month. Multivitamins and calcium tablets are supplemented, urine ketones are tested twice a week (preferably greater than 3+), and weight is weighed once a week. The initial 3-month follow-up is required once a month to review blood lipids, blood routine, liver and kidney function, trace elements, etc. The 3-month follow-up can be extended to 3-6 months, with selective blood tests along with urological ultrasound and electrocardiogram, etc. The efficacy of MAD can be evaluated after 3 months, and MAD can be stopped slowly if it is ineffective. Adverse effects of KD The limited research data available did not find any serious adverse reactions, and most of the reported adverse reactions are similar to those in children. Gastrointestinal reactions (vomiting, bloating, diarrhea), some patients especially give up continued adherence to KD mostly because they cannot tolerate the gastrointestinal side effects. Hypercholesterolemia, dyslipidemia, atherosclerosis, many patients are reluctant to undergo KD treatment for fear of developing such complications secondary to cardiovascular disease. Constipation, hair loss, weight loss, menstrual disorders, drowsiness, fatigue, vitamin and mineral deficiencies, etc. There is a lack of reports on kidney stones, excessive ketosis, and acidosis due to increased urinary calcium or creatinine ratios. However, some studies have found benefits of KD application in adult RE, such as concentration, more fluent expression, improved well-being and health of life, and improved mood. Most of the adverse effects can be treated and prevented: hyperlipidemia can be normalized by reducing the proportion of saturated fatty acids and increasing the proportion of unsaturated fatty acids in the diet; weight loss can be increased with additional calorie intake; supplementation with calcium, zinc, selenium and vitamin D to prevent vitamin and mineral deficiencies; and oral potassium citrate can prevent kidney stones. KD is not recommended for adult RE patients with comorbid diabetes, hypertension, cardiovascular disease, peripheral vascular disease, hyperlipidemia, renal calculi, malignancy, chronic liver and kidney disease, mitochondrial disease, and fatty acid metabolic disorders. Although the number of cases of KD applied to adult RE is small, it still demonstrates better antiepileptic efficacy. Whether the KD has sustained antiepileptic efficacy in adult RE and whether other adverse effects will occur with the KD still require long-term observation and research. Clinicians can draw on the antiepileptic mechanism of the ketogenic diet to enhance the standardized management of patients, and can give advice on a low-carbohydrate, high-fat diet. The good efficacy of KD predicts that it is expected to be started at the early stage of seizures, and it is recommended that adult RE patients without surgical indications can be treated with KD as soon as possible after excluding contraindications.