No weight up and down how much normal, weight control is related to the body mass index (BMI), generally normal need to control between 18.5-23.9 kg / m ². As each person’s dietary structure, the amount of food there will be some differences, at the same time, the amount of water and exercise will also have a certain impact on the weight of the different. Normal male standard weight (kg) = [height (cm) – 80] x 0.7, female standard weight (kg) = [height (cm) – 70] x 0.6. Body mass index (BMI) = weight (kg) / height (m^2). If the BMI is between 18.5 and 23.9 kg/m², all are normal. If the weight fluctuates too much or there is unexplained wasting, consider whether it is caused by diabetes, hyperthyroidism, tumors, and gastrointestinal diseases. If the patient’s weight fluctuates significantly, he or she should go to the hospital in time to avoid delays.