The full name of hyperthyroidism is hyperthyroidism. As a result of excessive secretion of thyroid hormones, the body’s metabolic capacity becomes hyperactive and patients experience irritability, palpitations, fear of heat, thick neck, protruding eyes, excessive eating, and weight loss. Most of the hyperthyroid patients will lose weight when they are ill. If they become fat instead of thin, it may be related to hyperphagia, improvement of the disease, excessive medication, etc. It may also be the occurrence of atypical hyperthyroidism: 1. Hyperphagia: Most of the hyperthyroid patients have hyperphagia. When the metabolic capacity is smaller than the calories produced by eating, it will increase the fat in the body and have the performance of becoming fat; 2. Improvement of the disease: After standardized If thyroid hormones can be effectively controlled through standardized treatment, the metabolic level of the body will decrease and weight will increase. Therefore, gaining weight may also be a clinical indication of effective treatment of hyperthyroidism; 3. Excessive medication: If excessive medication is used in the treatment of hyperthyroidism, symptoms of hypothyroidism will appear and weight will continue to increase. The onset of hyperthyroidism is dominated by a single system symptom, which may only have the performance of the nervous system or circulatory system, such as hand trembling, excessive sweating, panic, irritability, hyperphagia and other symptoms, while the performance of metabolic symptoms of the digestive system such as wasting is not obvious. In addition, when hyperthyroidism patients show weight gain instead of weight loss, they need to be diagnosed differently from transient thyrotoxicosis. Blood test results of both diseases may show elevated T3 and T4 levels and reduced thyroid stimulating hormone levels, but the latter is not due to excessive hormone synthesis and secretion caused by hyperthyroidism, but rather to destruction of thyroid follicular cells, resulting in elevated T3 and T4 levels, so the symptoms of increased metabolism and wasting associated with hyperthyroidism do not occur.