The main reason for getting thinner after thyroid cancer surgery is to consider whether the postoperative period is combined with hypothyroidism, poorer diet and insufficient nutritional supplementation. If, in these cases, T3 and T4 can be found to be significantly lower and TSH significantly higher, exogenous supplementation of thyroid hormone levels is needed to improve the patient’s quality of life and nutritional status, thus helping to restore body mass and weight. Of course, it also depends on whether the thyroid cancer has been radically removed surgically. If the thyroid cancer is not radically removed and is combined with hyperthyroidism, the patient will lose more and more weight, have progressive weight loss, and even have excessive sweating and hyperphagia.