The liver function test is a relatively routine test at present, and it is necessary to fast 8-12 hours before this test. The main reason for this is to avoid errors in the test after eating and drinking. First, when we perform a liver function test, it involves the measurement of liver enzyme values such as alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase. These enzymes help the liver convert food into energy, so the liver secretes more of these enzymes after eating, thus affecting the liver function rating regarding the enzymes. In addition, liver function tests also involve albumin and total protein, which help maintain the normal function of muscle, bone, blood and organ tissues. Low protein levels may occur as a result of liver or kidney disease or nutritional problems. When tested after eating, these values can also be inaccurately tested, adversely affecting the diagnosis of disease. Liver function tests require a blood draw, and the blood portion of the test is primarily the serum component that has been centrifuged. Performing a blood draw after eating will in many cases increase the viscosity of the blood and slow down the blood flow, making it very difficult to collect blood. Some people like to eat high-fat, high-protein foods, and after eating these foods, there is a risk that the serum will not be well separated during blood centrifugation, which will affect the test. The need for fasting before liver function tests is a long-standing principle that needs to be observed. The main reason for this is to facilitate the test and to get a more realistic and accurate result.