Why does fatty food make you feel full?

When healthy young adults receive loxiglumide intravenously while fat is infused into their duodenum, their blood levels of cholecystokinin rise instead of falling, suggesting that the body's regulatory system for this hormone responds in an unexpected way.

When healthy young adults receive an intravenous fat solution at a standard dose, their blood levels of a digestive hormone called cholecystokinin rise from 2.4 to 4.8 picomoles per liter, indicating that normal dietary fat levels trigger the body’s natural production of this hormone.

When fat is delivered directly into the small intestine of healthy young adults, it leads to a greater feeling of fullness specifically for high-fat foods, compared to other types of foods, which may indicate that the body's satiety response to fat is distinct from its response to other nutrients.

When fat is delivered directly into the small intestine of healthy young adults at a rate of 6 grams per hour, it triggers the release of a hormone called cholecystokinin, which leads to increased feelings of fullness and reduced eating afterward. Blocking this hormone reduces those effects.

When a drug called loxiglumide blocks CCK-A receptors in healthy young adults, the feeling of fullness normally triggered by fat in the small intestine does not occur, indicating that CCK-A receptor activity is required for this physiological response.