Cholecystokinin (CCK) is a peptide hormone found in the gastrointestinal tract and brain that is involved in the regulation of food intake, digestion, and mood. It is released in response to the ingestion of fat and protein, and is known to stimulate the release of bile from the gallbladder and pancreatic enzymes for digestion. Research on CCK has primarily focused on its role in appetite regulation and satiety. Studies have shown that CCK acts as a satiety signal, signaling to the brain that the stomach is full and reducing the desire to eat. This has led to investigations into the potential therapeutic use of CCK analogues for weight management and the treatment of obesity. In addition to its role in appetite regulation, CCK has also been implicated in various physiological and pathological processes, including anxiety, stress response, inflammation, and gastrointestinal disorders such as irritable bowel syndrome. Overall, research on cholecystokinin continues to uncover its diverse functions and potential therapeutic applications in a variety of health conditions.