The primary role of the thyroid gland in metabolism is to regulate the body's metabolic rate through the production of hormones such as thyroxine (T4) and triiodothyronine (T3). These hormones influence how the body uses energy, affecting various functions such as heart rate, body temperature, and the metabolism of carbohydrates, proteins, and fats. A well-functioning thyroid is essential for maintaining a healthy weight and energy levels. Thyroid disorders can lead to various metabolic issues, including hypothyroidism and hyperthyroidism, impacting overall health.