The primary purpose of fasting for 8~10 hours before screening is to empty the stomach of foods so images obtained from the upper gastrointestinal series would not be affected by the retention of food. Furthermore, eating before the blood sugar, cholesterol, hepatic function, and abdominal ultrasound examinations would affect the results. Fasting for 8 hours is, therefore, the only way to obtain accurate test results. No food and water before health screenings is a fundamental concept.