“Leptin (from Greek λεπτός leptos, “thin” or “light” or “small”) is a hormone predominantly made by adipose cells and its primary role is likely to regulate long-term energy balance.[6] As one of the major signals of energy status, leptin levels influence appetite, satiety, and motivated behaviors oriented towards the maintenance of energy reserves (e.g., feeding, foraging behaviors).”*
Leptin infulences the appetite in that it indicates the amount of fat stored in the body. This information assits the brain in determining how much and what type of nutriton is required to maintain sufficient reserves based on estimated needs. Leptin and Ghrelin together have a combined effect on our overall appetite and hunger feelings.
*https://en.wikipedia.org/wiki/Leptin