Blood draws for HIV do not require fasting and checking antigenic antibodies for HIV is not affected by eating. Antigen and antibody testing for HIV is the gold standard for diagnosis of HIV infection. Most initial screening tests are done to check for antibodies to HIV, and if the test is positive then a confirmatory test is done using a protein blotting assay. If the confirmatory test is also positive, the diagnosis of HIV infection is confirmed. After the diagnosis of HIV infection is confirmed, the patient should be further tested for HIV viral load and CD4 lymphocyte count, both of which do not require fasting. Fasting is required for liver function, blood lipids, and blood glucose, which may be affected by food intake. After the diagnosis of HIV infection, the patient should be treated with antiviral drugs as soon as possible to avoid further progression of the patient’s condition.