Cholecystokinin

Cholecystokinin (CCK) is a fullness hormone produced by cells in the stomach after a meal, similar to GLP-1. It helps in the production of energy, protein synthesis, digestion, and other biological activities. It also increases the production of leptin, a hormone that makes you feel full.

Obese people may be less sensitive to CCK's effects, which might contribute to chronic overeating. As a result, CCK sensitivity may be reduced even further, creating a negative feedback loop. CCK levels should be kept at a healthy level by consuming a lot of protein. According to some studies, a high-protein diet can help increase CCK levels and so fullness. While research on the subject is limited, some data suggest that regular exercise might help increase CCK levels.