Which hormone is primarily responsible for regulating metabolism?

• A. Growth hormone
• B. Thyroid hormones
• C. Insulin
• D. Adrenaline

Answer: (B)

The correct choice highlights thyroid hormones as the primary regulators of metabolism. These hormones, specifically thyroxine (T4) and triiodothyronine (T3), play a crucial role in maintaining the body's metabolic rate. They influence how the body converts food into energy, regulates heart rate, and plays a key role in overall growth and development.

Thyroid hormones increase the basal metabolic rate, meaning they directly affect how quickly the body uses energy at rest. This regulation enables the body to balance energy demands with intake.

Other hormones mentioned do play roles in metabolic processes but are not primarily responsible for regulating overall metabolism. For instance, growth hormone is more focused on stimulating growth and cell reproduction, insulin regulates blood sugar levels by facilitating glucose uptake, and adrenaline primarily prepares the body for 'fight or flight' responses, which can temporarily elevate metabolism but does not regulate it consistently. Thus, thyroid hormones are identified as the key players in the long-term regulation of metabolic processes.