I. Metabolism in patients with liver disease: At present, domestic and foreign scholars regard the application of indirect energy meter (metabolic vehicle) to determine resting energy expenditure as the “gold standard”. Patients with chronic liver disease have abnormal substance and energy metabolism. There are many studies on cirrhotic patients at home and abroad, and some scholars believe that abnormal metabolism of the three major nutrients is an independent prognostic factor for cirrhotic patients. The reports on the total energy consumption of cirrhotic patients are different, some studies believe that 58% of cirrhotic patients have basically normal energy metabolism, and 12% are in low energy metabolism state; some studies believe that cirrhotic patients are in high energy metabolism state, and the patients have high rate of fat oxidation [5]. Hypermetabolizers often lose weight and are more prone to malnutrition, and their morbidity and mortality increase. The cause of hypermetabolism is unknown, and some scholars believe that it is not related to gender, aetiology, disease severity, protein deficiency, ascites, or tumors. Our study found that patients with chronic liver disease have significant problems with abnormal material energy metabolism. Patients with chronic severe liver, cirrhosis, and chronic hepatitis had hypometabolic resting energy expenditure measurements below the normal expected values calculated by the H-B formula. It has been noted that the respiratory quotient of cirrhotic patients is significantly lower than that of healthy controls, as evidenced by a marked increase in fat oxidation and a marked decrease in carbohydrate oxidation; this change in energy metabolism is similar to a starvation state, which may lead to malnutrition. After nocturnal energy administration to cirrhotic patients, their respiratory quotient, carbohydrate and fat oxidation rates recovered significantly and finally approached normal levels. This suggests that nocturnal energy supply may have a role in correcting metabolic abnormalities and preventing malnutrition in cirrhotic patients.Yamanaka et al. also suggested that cirrhotic patients exhibit a starvation state in the early morning metabolic state due to a lack of glycogen reserves, and that maintenance of the energy supply prevents energy deprivation at dawn.Chang et al. found that respiratory quotient was significantly decreased in cirrhotic patients when they were fasted at night; if they were supplemented with 50g of glucose at bedtime, an increase in RQ occurred. glucose, an increase in RQ and CO2 production occurred, while fat and protein oxidation decreased. Therefore, it is believed that appropriate glucose supplementation at bedtime in cirrhotic patients enables economical utilization of fuel and reduces fat and protein consumption. Our study likewise suggests that both patients with cirrhosis and chronic heavy hepatitis have lower than normal RQ and significantly lower oxidative utilization of carbohydrates compared to normal or slow hepatitis B. Instead, there is an increase in the rate of fat and protein oxidation, and the oxidation of fats is more pronounced in slow heavy liver compared to cirrhosis, and this change in energy metabolism and RQ resembles a starvation state. The occurrence of malnutrition in patients with chronic liver disease will increase the risk of complications and death. Poor diet further increases the risk of hepatic encephalopathy, infections and gastrointestinal bleeding, and significantly increases the incidence of persistent ascites. Although a large number of studies have shown that malnutrition does reduce the survival time of patients, it is controversial because it is not certain whether the increase in mortality is caused by malnutrition or by the progression of the disease itself, and some scholars believe that malnutrition can be used as a predictor of prognosis as an independent risk factor. Nutritional supportive therapy for patients with chronic liver disease: 1. Energy intake: The 2009 European Society for Enteral and Parenteral Nutrition guidelines for parenteral nutrition in liver disease state that: the overall energy expenditure of patients with cirrhosis is measured to be approximately 130% of the basal metabolic rate, and that it is safe to assume that the energy requirements of patients with cirrhosis are 1.3 times the basal metabolic rate in clinical practice. If possible, resting energy expenditure values should be measured using indirect calorimetry. In patients with alcoholic steatohepatitis who are moderately or severely malnourished and whose needs cannot be met by oral or enteral nutritional methods, parenteral nutritional support should be initiated immediately, with a recommended energy intake of 1.3 times basal metabolic rate. In complete parenteral nutrition, glucose is recommended as the carbohydrate source, which should account for 50%-60% of the non-protein energy requirement, and fat accounts for 40%-50% of the non-protein energy requirement. 2. Nutrient intake: The guidelines for parenteral nutrition in liver disease developed by the European Society of Enteral and Parenteral Nutrition in 2009. Parenteral Nutrition Guidelines for Liver Disease, 2009: Nutrient intake in patients with chronic liver disease, especially cirrhosis, should be based on glucose as a source of carbohydrates, accounting for 50-60% of the non-protein energy requirements; the n26 unsaturated fatty acid content of fat emulsions should be lower than that of traditional pure soybean oil emulsions, and account for 40-50% of the non-protein energy requirements. Amino acid supply should be 1.2 g/kg/day for patients with compensated cirrhosis without malnutrition and 1.5 g/kg/day for patients with decompensated cirrhosis associated with severe malnutrition. patients with mild hepatic encephalopathy (≤ II degree) can be given standard amino acid preparations directly, while patients with severe hepatic encephalopathy (III – IV degree) should be given standard amino acid preparations with a higher proportion of branched-chain amino acids and lower levels of aromatic amino acids, methionine, tryptophan, and other amino acids. For patients with severe hepatic encephalopathy (III – IV degrees), preparations containing more branched-chain amino acids and less aromatic amino acids, methionine and tryptophan should be used. Total nutrient supplementation is recommended during the first two weeks of parenteral nutrition in patients with chronic liver disease. Nutritional imbalances are very common in patients with chronic liver disease and can not only severely impair the reserve function and regenerative capacity of the liver, but also affect the patient’s prognosis as a clear, independent risk factor. Research on nutritional support in chronic liver disease is still in its infancy, and many issues are still under investigation. One of the important responsibilities of focusing on nutritional therapy for patients with chronic liver disease is to allow patients to introduce the concepts and methods of nutritional support into their family life and to improve their quality of life. Our goal is to enable a wide range of patients with liver disease to promote clear thinking and improve mood; improve physical fitness; improve sleep quality; improve resistance to infection; improve IQ; delay and reduce disease recurrence; and prolong life by means of rational and appropriate dietary nutrition and nutritional supportive therapeutic interventions. The realization of this goal is also a test of “optimal nutrition”.