Final answer:
The endocrine system is responsible for regulating metabolic activities of the body.
Step-by-step explanation:
The system responsible for regulating metabolic activities of the body is the endocrine system. The endocrine system secretes hormones into the blood that travel to body cells and influence their activities, including metabolic processes. Hormones like insulin and glucagon play a key role in maintaining homeostasis of blood glucose levels, which is essential for proper metabolism.