Which hormone is primarily responsible for regulating appetite?

Leptin is the key hormone primarily responsible for regulating appetite. It is produced by adipose (fat) tissue and plays a crucial role in energy balance by signaling the brain to suppress hunger when energy stores are sufficient. When fat stores increase, leptin levels rise, promoting a feeling of fullness and reducing food intake. Conversely, when fat stores decrease, leptin levels drop, which can lead to increased appetite and food consumption. This mechanism of appetite regulation is important for maintaining a healthy weight and overall energy homeostasis in the body.

Cortisol, while it does affect metabolism and appetite, is primarily linked to stress responses and can lead to increased appetite, especially for high-energy foods, but it isn't the main regulator of appetite. Adrenaline is involved in the body's fight-or-flight response and its effects on appetite are more about short-term energy needs rather than long-term appetite regulation. Insulin primarily regulates blood sugar levels and also has some influence on hunger; however, its main role is not directly targeted at appetite control like leptin's is.