After the condition of hyperthyroidism is under control, the patient’s weight will increase. During the onset of hyperthyroidism, the body is in a state of high metabolism, and the protein and fat in the body will be decomposed, resulting in weight loss, and at the same time, some patients with hyperthyroidism will have diarrhea, which will further exacerbate the weight loss. After the control of hyperthyroidism, the hypermetabolic symptoms will be relieved, the metabolism of the body will return to normal, protein and fat will be re-stored in the body, and the digestion and absorption function will be restored, so the weight will increase. Generally speaking, after the hyperthyroidism symptoms are under control and the FT3 and FT4 are normalized in clinical examination, the dosage of antithyroid medication can be reduced, and hypothyroidism may be caused by taking the medication without checking for a long period of time. Therefore, patients with hyperthyroidism should go to the hospital regularly to check the thyroid function, liver function and kidney function, and adjust the medication according to the doctor’s instructions.