Hyperthyroidism is an abnormality in body metabolism caused by excessive production of thyroid hormones, mostly with symptoms such as wasting, panic and irritability, rarely appearing to become fat. The actual reason why hyperthyroidism patients become fat is to choose the solution according to the cause of the disease, and not to stop the medication or diet to lose weight without permission. 1. The condition has improved: when the condition of hyperthyroidism is controlled, the weight of the patient will rise, which is actually a normal trend. The reason is that during the treatment of hyperthyroidism, the high level of thyroid hormones in the body leads to high metabolism and high catabolism, so although hyperthyroidism patients eat a lot, they do lose weight. When the hyperthyroidism is under control and the T3 and T4 levels are in the normal range, this high metabolism and high catabolism can be suppressed. Patients with hyperthyroidism will find that their weight has increased, which is a physiological phenomenon of improvement. It is recommended to continue to actively control the disease, try to control the total number of calories in the diet and not to overeat; 2. cause drug-related hypothyroidism. These patients are prone to mucinous edema, which can cause the hyperthyroid patient to appear to gain weight and have the appearance of gaining weight. In this case, the dosage of antithyroid drugs should be adjusted in time under the guidance of the doctor, and the drugs should not be increased or decreased at will. The weight gain will be controlled when the condition is stabilized; 3. Fat accumulation: If hyperthyroid patients do have fat accumulation in their bodies, it will lead to weight gain. For this kind of real fat gain, lifestyle interventions are mainly needed. For example, the diet should control the total calories, eat more coarse fiber-rich and light foods, eat small and frequent meals, and cooperate with exercises that you can tolerate, and it is also recommended not to use weight loss drugs freely during this period to avoid affecting your health.