Fasting is required to test liver function because diet tends to affect liver function test results. Liver function test is an overall assessment of liver function and belongs to the biochemical tests commonly used in clinical practice. In previous tests, it has been found that there is a difference in liver function test results between pre-meal and post-meal, and that there is a correlation between liver function test results and diet, so it is recommended to fast when drawing blood for liver function tests. Liver function test and also pay attention to 1~3 days before the test, it is best not to eat high-fat food, and do not drink a lot of alcohol, eat a light, low-fat diet. Avoid food factors affect the accuracy of the results, not conducive to the diagnosis and analysis of the condition. If there is an abnormal liver function test result, it is recommended to consult a doctor in time to clarify the cause of the disease with the help of the doctor and carry out targeted treatment or therapy.