What condition is characterized by an underactive thyroid and may cause weight gain or loss?

Hypothyroidism is the condition characterized by an underactive thyroid. In this state, the thyroid gland does not produce sufficient thyroid hormones, which play a crucial role in regulating metabolism, energy levels, and various bodily functions. When hormone levels are low, metabolic processes slow down, potentially leading to weight gain due to decreased calorie expenditure and fat accumulation. Conversely, some individuals may experience weight loss, particularly if they have fluctuations in thyroid hormone levels or issues with appetite regulation.

Symptoms of hypothyroidism can include fatigue, depression, cold intolerance, and changes in skin and hair texture, alongside weight changes. The management of this condition typically involves hormone replacement therapy to normalize thyroid hormone levels and alleviate symptoms.

This understanding of hypothyroidism highlights the importance of recognizing the effects of thyroid function on metabolism and weight, distinguishing it clearly from conditions like hyperthyroidism, adrenal insufficiency, and diabetes insipidus, which have different underlying mechanisms and clinical manifestations.