Breakfast is allowed for TB tests, while some lab tests require fasting and should be performed in strict compliance with the doctor’s instructions. The diagnosis of TB can be considered in conjunction with typical symptoms (low afternoon fever, night sweats, cough, etc.) and relevant tests, of which finding Mycobacterium tuberculosis is the gold standard. Tuberculosis examination includes tuberculin test (PPD), chest radiograph, chest CT, sputum antacid staining, sputum culture of tuberculosis bacilli and other tests, all of which are not related to eating, so they do not require fasting, and it is possible to eat breakfast. There are many items that require fasting, such as liver function, kidney function, blood lipids, blood sugar, thyroid function, etc., and abdominal ultrasound, abdominal CT, gastroenteroscopy, etc., which should be carried out in strict accordance with the physician’s requirements, as failure to comply with the doctor’s instructions may result in inaccurate results or inability to carry out the examination.