Final answer:
The posterior pituitary gland is the least involved in regulating metabolism.
Step-by-step explanation:
The endocrine gland that is least involved in regulating metabolism is the posterior pituitary gland. The posterior pituitary is responsible for secreting hormones such as vasopressin and oxytocin, which play a role in regulating fluid balance and reproductive functions, respectively. These hormones do not directly influence metabolism.