Several hormones signal fullness: CCK responds to fat and protein, PYY rises as food moves through the gut, GLP-1 slows gastric emptying. Research by Batterham shows protein triggers the strongest PYY response. These hormones respond to actual nutrients—protein, fiber, fat—not liquid calories or ultra-processed foods that bypass the satiety system.
This companion covers CCK, PYY, GLP-1, and leptin, what triggers them, and what doesn’t activate your body’s fullness signaling. (3 min read)