Which hormone is involved in stimulating appetite?

• A. Leptin
• B. Insulin
• C. Neuropeptide Y
• D. Ghrelin

Answer: (D)

Appetite regulation hinges on signals that push you to eat and signals that tell you to stop. Ghrelin is the stomach-derived hormone that directly triggers hunger. When the stomach is empty, ghrelin levels rise, travel through the blood, and bind to receptors in the hypothalamus. This activates neurons that promote feeding, especially the orexigenic pathways, leading to increased hunger and food intake. Ghrelin levels fall after a meal, which helps curb appetite.

Leptin is a hormone from fat tissue that signals energy stores and tends to suppress appetite. Insulin also communicates a fed state and can reduce appetite. Neuropeptide Y is a potent hunger-stimulating signal, but it’s a neuropeptide produced in the brain rather than a circulating hormone, which is why ghrelin is the best answer here.