Sudden weight gain should be considered in two categories: physiological and pathological factors, while physiological causes do not require special treatment, pathological causes need attention. Pathological reasons mainly include Cushing’s syndrome, hypothyroidism, drug factors, kidney disease, polycystic ovary syndrome, etc. I. Physiological causes: As we grow older, the body will experience a decline in the basal metabolic rate, resulting in the body being prone to sudden weight gain at an age. In addition, if there is a family history of genetics, the family has obese patients, but also easy in the case of lifestyle without moderation, weight gain, sudden fat phenomenon, such as circadian rhythm irregularities, some people are prone to stress obesity. Second, pathological reasons: 1, Cushing’s syndrome: due to a variety of reasons resulting in the abnormal increase in adrenal glucocorticoid secretion, some patients will appear weight gain, and will show a special body shape, usually a centripetal obesity, full-moon face, buffalo back, and the abdomen, the armpits are prone to purple lines. In addition to sudden fatness, it is easy to combine hypertension, hyperglycemia, hypokalemia, or an increase in hair; 2. Hypothyroidism: due to the decrease in the synthesis and secretion of thyroid hormones in the body, it is easy to have mucinous edema, which looks like sudden fatness from the appearance. In fact, it is not an increase in fat accumulation, but an increase in weight due to mucinous edema; 3, drug factors: such as rheumatic immune system diseases or other diseases, patients taking glucocorticoids, such as prednisone, prednisone, etc., can lead to weight gain in the human body; taking drugs related to mental illness can also lead to sudden weight gain in the human body, such as olanzapine; 4, kidney disease: kidney Water metabolism problems, will trigger edema, water can not be discharged, thus leading to weight gain, fat; 5, polycystic ovary syndrome: with high androgen levels as the main feature, androgen is too high will easily lead to obesity. Some patients have insulin resistance, leading to hyperinsulinemia, so it also causes obvious obesity. Therefore, when sudden weight gain occurs, it is important to rule out pathological causes. If the sudden weight gain is due to physiological reasons, it is mainly through diet control, appropriate exercise, and increase the body’s basal metabolic rate to help control weight.