This symptom is clinically considered to be caused by a feeling of fasting: one is a feeling of hunger caused by lowered blood sugar; the other may be a false sense of fasting caused by too much boredom, fatigue or emotional instability. The former is a real physiological fasting feeling, the latter is caused by mental factors, if there is no real hunger, it is considered to be mentally related, if this situation occurs, you can pay proper attention to rest, to do something else to distract, usually pay attention to the regularity of diet, should be able to adjust over. There is also a situation in which women of childbearing age should also consider whether they are pregnant, there will also be such symptoms, it is best to go to the hospital to check and confirm whether they are pregnant.