How does the thyroid affect body energy and temperature?

The thyroid gland, located in the neck, produces hormones called thyroxine and triiodothyronine. These hormones help set the pace at which cells use energy, affecting how quickly the body burns fuel and generates heat. They also play a role in growth and brain development, especially in childhood. The pituitary gland helps regulate thyroid activity using thyroid-stimulating hormone, or TSH. If the thyroid is underactive or overactive, people can feel tired, cold, anxious, or unusually warm.