What is the effect of thyroid hormones on metabolism?

Thyroid hormones, particularly thyroxine (T4) and triiodothyronine (T3), play a crucial role in regulating metabolism. Their primary effect is to increase the metabolic rate, which in turn enhances the body’s energy expenditure. This increase is achieved by stimulating various biochemical processes, including carbohydrate metabolism, protein synthesis, and lipid metabolism.

Additionally, thyroid hormones significantly influence growth and development, particularly in tissues that are highly metabolic, such as the brain, heart, and skeletal muscle. This is why they are essential not only for energy metabolism but also for proper growth and development during childhood and adolescence.

The other options do not reflect the well-established physiological roles of thyroid hormones. Decreasing the metabolic rate, having no effect at all, or increasing fat storage do not accurately represent how these hormones function in the body. Their primary role is to enhance metabolism and support various growth processes, which is why the correct choice emphasizes their capacity to increase metabolic rate and influence growth and development.