When you eat fat, your body releases a hormone called cholecystokinin that signals the brain to reduce hunger and promote a feeling of fullness.

Obese mice don't respond as well to a gut hormone (CCK) that normally tells the brain to stop eating fat—and even after they lose weight, this blunted response doesn't come back.

In older adults, eating a high-fat diet does not reduce the ability of the hormone cholecystokinin-8 to signal fullness after eating.

A two-week high-fat diet does not change how effectively the hormone CCK-8 reduces hunger in healthy older adults, as measured by how much food they eat afterward.