Generally speaking antithyroid drugs do not cause fat. Hyperthyroidism refers to hyperthyroidism, which is a series of manifestations such as excessive thyroid hormones in the blood circulation, causing increased sympathetic excitability and hypermetabolism, such as agitation, irritability, insomnia, palpitations, fatigue, fear of heat, lethargy, and hyperphagia. If the patient’s condition is mild, anti-thyroid drugs can be chosen, such as propylthiouracil, methimazole, etc. The side effects of anti-thyroid drugs include granulocyte deficiency, rash, toxic liver disease, vasculitis, etc., and there is no obesity-inducing side effects. Generally speaking, patients’ symptoms of hyperthyroidism will be alleviated and the symptoms of lethargy will be improved, which may be a sign that the disease is getting better. If you take anti-thyroid medication, weight gain significantly, causing overweight or obesity, it is recommended to consult a doctor in a timely manner, under the guidance of the doctor to clarify the cause.