There are many factors that can cause fatty liver: including excessive lipid intake, lack of phospholipids and proteins for lipoprotein synthesis, malnutrition, foreign toxins or drugs, etc. 1, obesity: obesity has become an important cause of fatty liver in developed countries and regions, and the degree of obesity is closely related to the development of fatty liver and steatohepatitis. , 2, diabetes: especially type 1 diabetes and fatty liver is closely related. And most of them are moderate or more than moderate fatty liver, and the incidence of fatty liver hepatitis increases in those who receive insulin therapy. The mechanism is due to the lack of insulin, so that fat catabolism increases and lipoprotein synthesis decreases, producing hyperlipidemia and fatty liver. 3, alcoholism: alcoholism is the most common cause of fatty liver and cirrhosis in Europe and the United States (in recent years, it has also become the main cause of fatty liver in China. In addition to the causes of alcohol itself and its metabolites, chronic alcoholism accompanied by malnutrition is also involved in the development of liver fibrosis, continuous alcohol drinkers continue to progress, alcoholic liver fibrosis as an important stage of regression and prognosis, is an opportunity for treatment. Active and successful abstinence from alcohol is the most effective measure to prevent and treat fatty liver. Abstinence from alcohol not only improves the basic cellular dysfunction caused by ethanol overdose, but also blocks the ethanol-dependent tissue damage caused by self-reinforcing damage factors that occur during the course of the disease. Quitting alcohol can significantly improve the overall physical quality (appetite, physical fitness, memory, work efficiency) of fatty liver patients, and also normalize the morphological, histological and biochemical indicators of the liver. 4, hyperlipidemia: all types of hyperlipidemia are seen in fatty liver patients, the most closely related is hypertriglyceridemia, often accompanied by obesity and diabetes. Simple hypercholesterolemia without obesity and diabetes has a less pronounced effect on fatty liver formation than hypertriglyceridemia. High-fat diet, excessive sweets and alcoholism can induce hyperlipidemia, which in turn is involved in the development of fatty liver. 5, viral hepatitis: viral hepatitis caused by various hepatophilic viruses is a more common cause of fatty liver. Recent studies have found that some hepatitis C virus and hepatitis D virus infections can cause steatosis of large and small vesicular hepatocytes, respectively. Fatty liver can be induced during recovery from all types of viral hepatitis as well as chronic viral infections, and can exacerbate liver damage in alcoholics. Current HCV infection (positive serum HCV-RNA) is usually considered an exclusion criterion for the diagnosis of NASH, but some investigators refer to HCV-infected patients with histologically typical steatohepatitis manifestations, rather than the portal zone lymphocytic infiltration and mild to moderate steatosis exhibited by hepatitis C, as NASH. In fact, about 10% of hepatitis C is combined with NASH. 6. Drug-related liver damage. Most drugs are excreted in the liver through biotransformation. In the process of drug metabolism, the liver can be damaged by the drug itself or its metabolites. The incidence of drug-related liver damage has increased in recent years with the increasing variety of drugs used. Fatty liver is the most common type. The manifestations of drug-related fatty liver are diverse and are related to the type of drug, dose, duration of exposure, absorption pathway, body status, genetic factors, and in some cases, damage to other organs, and dozens of drugs can induce fatty liver and steatohepatitis – such as nucleoside analogs. Menadione, azacitidine, methotrexate, etc., anti mitotic drugs: bleomycin, puromycin, tetracycline, etc., and other drugs. Amiodarone, dichloroethyl ether, estrogen, glucocorticoids, etc. A few drugs such as anti-arrhythmic and anti-anginal drugs cause fatty liver (can be complicated by fibrosis through steatohepatitis), so it should be paid attention to. 7, malnutrition fatty liver is seen in parenteral nutrition, malnutrition, protein synthesis disorders and other lesions.