Which hormone is primarily responsible for regulating metabolism in the body?

Thyroxine, also known as T4, is a hormone produced by the thyroid gland that plays a crucial role in regulating metabolism throughout the body. It affects various metabolic processes, including the rate of energy expenditure, the metabolism of carbohydrates, fats, and proteins, and the overall metabolic rate. By increasing the basal metabolic rate, thyroxine helps control how quickly cells use energy and synthesize proteins, which is fundamental for growth and maintenance of body tissues.

In addition to its primary function in regulating metabolism, thyroxine has a significant impact on other physiological processes, such as thermogenesis, heart rate, and the regulation of body temperature. This comprehensive role in energy metabolism makes thyroxine the principal hormone governing metabolic activity in the body, distinguishing it from other hormones that, while influential, do not primarily regulate metabolism in such a direct manner.