Fatty liver is an excessive accumulation of fat in the liver cells. Fatty liver occurs when the accumulation of fat in the liver exceeds 5% of the normal weight of the liver. In the large fat droplet type of fatty liver, large fat droplets fill the hepatocytes, displacing the nuclei to the periphery. In the small fat droplet type of fatty liver, small fat droplets accumulate in the liver and the cells are foamy with centered nuclei. Diffuse steatosis of the liver is often zonally distributed and is associated with many of the diseases seen clinically. In developed countries, alcoholism, obesity, and diabetes mellitus are the most common causes of large fatty droplets of fatty liver, while other causes include malnutrition (especially protein-deficient diets in children with kwashiorkor’s disease), inborn disorders of metabolism (gluconeogenesis, galactose, tyrosine, or homocysteine), medications (e.g., corticosteroids), and systemic diseases with fever. Small fatty droplets of fatty liver can occur in acute fatty liver of pregnancy, Rey syndrome, some hepatotoxic drugs (valproic acid, tetracycline, salicylates) and inborn defects of metabolism (e.g., urea cycle enzyme deficiencies or impaired oxidation of FFA in mitochondria). In our country, the main causes of fatty liver are: high-fat diet, sweet tooth, and chronic alcohol consumption. Symptoms, signs and diagnosis of fatty liver with large fat droplets are often detected during physical examination and are most common in patients with alcoholism, obesity or diabetes mellitus, and may also present with right upper abdominal pain, tenderness and jaundice. The biochemical abnormalities commonly seen in fatty liver are often inconsistent with other liver diseases. Alkaline phosphatase or aminotransferase may be mildly elevated, and ultrasound, especially CT, may reveal excess fat. Fatty liver may be diagnosed only by liver biopsy. The diagnosis of fatty liver may prompt further evaluation of the patient because the accumulation of fat in the liver may suggest the role of hepatotoxins and the presence of unknown diseases or metabolic disorders. Fatty deposits are also found in the liver in nonalcoholic fatty liver disease, which is common in female patients who are obese or diabetic. It can also occur in jejunal bypass, in malnourished individuals, and in association with certain medications (e.g., glucocorticoids, synthetic estrogens, ethamidofuranone, tamoxifen), and can present with hepatomegaly, with histologic diagnosis relying on large lipid droplet-type steatosis and lobular inflammation, sometimes accompanied by fibrosis and Mallory vitreous vesicles. This is often seen in patients who have had liver biopsies for other reasons, such as a 2- to 3-fold elevation of plasma aminotransferases in asymptomatic patients. The diagnosis is made by ensuring that no alcohol has been consumed. Small droplet fatty liver disease has obvious symptoms such as fatigue, nausea, and vomiting, which can be rapidly followed by jaundice, hypoglycemic coma, and disseminated intravascular coagulation. The large fatty droplet type is harmless in itself and is usually reversible. It can even be reversed in focal patients (e.g., fatty liver in pregnancy, where early delivery can be life-saving). Alcoholic fatty liver disease can be associated with inflammation and necrosis (alcoholic hepatitis) and long-term liver damage with cirrhosis. Small droplets of fatty liver are more rapid in onset and can often be reversed if the patient survives. There is no specific treatment other than removing the cause or treating the underlying disease, and even obesity and diabetic fatty liver are not generally thought to progress to cirrhosis. Although hepatotoxic substances such as alcohol or carbon tetrachloride (which can also cause liver necrosis) can eventually lead to cirrhosis, there is no direct evidence that fatty liver can lead to cirrhosis, and a number of other factors need to be involved. The prognosis for NAFLD is usually good, with no histologic or clinical progression; some patients may develop liver fibrosis and progress to cirrhosis. Obese patients should lose weight, although no benefit has been demonstrated for this. Uncontrolled clinical reports have shown ursodeoxycholic acid treatment to be effective. Prevention and treatment of fatty liver is actually quite simple and does not require any medication. Fatty liver is reversible and can be prevented and reversed by paying attention to the following: 1. Eat a light diet; 2. Avoid alcohol; 3. Try to eat little or no sweets and drink no sweet drinks; 4. Walk fast for one hour a day, about 5 kilometers. Adhere to three months, you can see the effect.