Which hormone is involved in the regulation of energy metabolism and metabolic rate in animals?

Insulin is a crucial hormone involved in the regulation of energy metabolism and metabolic rate in animals. It is produced by the pancreas and plays a significant role in controlling blood glucose levels within the body. When food is consumed and carbohydrates are broken down into glucose, insulin is released to facilitate the uptake of glucose by cells for energy production. This process is essential for maintaining energy homeostasis, as it helps convert excess glucose into glycogen for storage in the liver and muscle tissue.

Additionally, insulin influences fat and protein metabolism, promoting the synthesis of fatty acids and inhibiting the breakdown of fat stores. Therefore, through its various actions, insulin significantly impacts overall metabolic rate and energy balance in animals.

The other hormones listed do not primarily focus on energy metabolism regulation. Oxytocin mainly regulates social bonding and reproductive functions, relaxin is involved in reproductive processes such as childbirth by relaxing the cervix and pelvic ligaments, and follicle-stimulating hormone primarily regulates the development of gametes in the reproductive system.