In the 12 hours before the physical examination is not allowed to eat, and the first 6 hours can not drink water, if there is already a physical examination plan, the first 3 days of the diet should also be controlled, not to eat too much fatty food, and not to drink alcohol. Physical examination is usually to check the body’s liver and kidney function, blood sugar, lipid indicators, fasting tests are required to reflect the actual situation of the body, if the physical examination is liver and gallbladder ultrasound, these tests require the body must fast for more than 12 hours, otherwise it may affect the results of the examination. Eating can interfere with the experimental results. If liver tests are performed, the results will be abnormally high transaminases, and if serological tests are performed, eating will cause the blood to be diluted, so that the concentration of various antibodies will also drop accordingly, which can easily mislead the clinical treatment and aggravate the condition in serious cases.