To check for anemia alone, routine blood tests are usually sufficient, and fasting is not required before the blood is drawn, which has no effect on the test results. If you want to check the cause of the disease, such as three types of anemia, liver function, etc., it is better to fast before the blood test. Generally, when checking liver function, patients are required to have blood drawn on an empty stomach because the stomach, gallbladder and liver of the organism are involved in the digestion and absorption of food after eating, and the indicators measured in this working state cannot objectively and truly reflect the state of the organism, so fasting is required. To check whether there is anemia, the focus is on the hemoglobin index, which is not affected by eating. Therefore, eating or not eating does not have much influence. However, in clinical practice, many things are often checked together when blood is drawn, and other tests may require fasting at this time, so it is also better to go on an empty stomach during the consultation to avoid a wasted trip.