What is a common symptom of hypothyroidism?

Weight gain and fatigue are indeed common symptoms of hypothyroidism. When the thyroid gland is underactive and does not produce enough thyroid hormones, the body's metabolism slows down. This decrease in metabolic activity can lead to unintended weight gain, as the body may become less efficient at using energy. Additionally, fatigue is a prevalent complaint among individuals with hypothyroidism due to reduced energy levels. The lack of thyroid hormones affects various bodily functions, including energy production, which often results in feelings of tiredness and lethargy.

The other symptoms listed, such as weight loss and increased energy, are more characteristic of hyperthyroidism, which involves an overactive thyroid. Increased heart rate and excessive sweating are also associated with hyperthyroidism rather than hypothyroidism. In the case of hypothyroidism, individuals are more likely to experience a slowed heart rate and less sweating due to the overall decrease in metabolic rate.