Being hungry quickly can be caused by dietary factors, heavy exercise, hyperthyroidism and diabetes. 1. Dietary factors: when eating less food or consuming insufficient protein, both may lead to hunger. 2. Exercise: Doing high-intensity exercise or physical work will easily lead to excessive energy consumption and fast hunger. 3. Hyperthyroidism: If the patient suffers from hyperthyroidism, it will easily lead to an increase in thyroid hormone secretion, resulting in a higher hormone metabolic rate, increased nutritional consumption, resulting in fast hunger. 4. Diabetes: When the blood sugar control is poor, it is easy to appear abnormal sugar metabolism, lack of energy, etc., may lead to the phenomenon of fast hunger, and also accompanied by polyuria, body wasting and other symptoms. Patients who are hungry should go to the hospital in time, and follow the doctor’s instructions for treatment after clarifying the cause of the disease.