What hormone is produced in the subcutaneous layer and helps regulate appetite?

Leptin is the correct answer because it is a hormone that is produced by adipose (fat) tissue, particularly in the subcutaneous layer. Its primary role is to help regulate energy balance by inhibiting hunger, which in turn helps to regulate body weight. When fat stores increase, leptin levels rise, signaling to the brain that enough energy is available and that appetite should be reduced. This feedback mechanism is crucial for maintaining energy homeostasis within the body.

Insulin, while also involved in appetite regulation, primarily functions to control blood glucose levels by promoting the uptake of glucose into cells. Estrogen, a sex hormone, does have some influence on appetite and metabolism, but its primary functions are related to reproduction and sexual development. Cortisol, known as the stress hormone, can affect appetite and metabolism during periods of stress, but its primary role is in the response to stress rather than direct appetite regulation. Thus, leptin stands out as the primary hormone produced in the subcutaneous layer specifically involved in appetite regulation.