It is better not to eat high-fat, high-calorie and high-sugar foods before blood donation. After consuming these foods, it may cause temporary elevation of blood glucose in the blood and temporary increase of blood lipid concentration, and even cause coeliac blood, commonly known as milk blood, which will affect the quality of blood donation. Before donating blood, try to avoid high sugar, high fat, high calorie food, before donating blood can be appropriate to eat light, easy to digest food, such as thin rice, vegetable soup, porridge and so on. Don’t donate blood on an empty stomach before donating blood, you usually need to donate 300-400ml of blood, some people may induce hypoglycemic episodes if they donate blood on an empty stomach, manifesting themselves as pale, sweaty, panicky, and in severe cases, even transient disorders of consciousness may occur. You can’t donate blood on an empty stomach before donating blood, but try to avoid high-fat and high-calorie foods and pay attention to a light diet.