Leptin is a key hormone that makes you feel full. Produced by fat cells and released into the bloodstream, leptin signals your brain's hypothalamus—the appetite regulation center—to suppress your hunger. This signals your body that you've had enough to eat.
However, it's important to note that other hormones also play a role in regulating appetite and satiety (feeling full). These include:
- Peptide YY (PYY): Released by the small intestine after eating, PYY signals the brain to reduce appetite.
- Cholecystokinin (CCK): Released in the small intestine, CCK contributes to feelings of fullness.
- Glucagon-like peptide-1 (GLP-1): Also released in the small intestine, GLP-1 helps regulate blood sugar and contributes to satiety.
- Amylin: Released from the pancreas alongside insulin, amylin slows gastric emptying and contributes to feelings of fullness.
- Insulin: Primarily known for its role in blood sugar regulation, insulin also plays a role in appetite regulation.
While leptin is often referred to as the "fullness hormone," it's more accurate to say that it's part of a complex hormonal system that governs appetite and satiety. The interplay between these hormones, along with factors like food intake, caloric density, and individual metabolism, determines how full you feel after a meal. Further research continuously reveals new insights into this intricate system.
Leptin: As noted in multiple sources, leptin's role is significant. One source states that "Leptin is a fullness hormone that works by telling your hypothalamus…that you're full." [Healthline] Another source explains that leptin "reduces a person's appetite by acting on specific centres of their brain to reduce their urge to eat." [Reference 1] It is also described as an "appetite suppressor" that's "the bigger player in our bodies' energy balance." [WebMD]
Ghrelin: Conversely, ghrelin, produced in the stomach, stimulates hunger when the stomach is empty. One source describes ghrelin as a hormone that "signals your brain when your stomach is empty and it's time to eat." [Cleveland Clinic]
In summary, while leptin is a major player in signaling fullness, it is one component of a complex system of hormones working together to regulate appetite.
