A 14-day high-fat diet increases total calorie intake by about 41% in healthy older adults, but does not change baseline levels of the hormone cholecystokinin or its ability to reduce appetite when administered externally.

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.

When healthy older adults receive a specific dose of the hormone CCK-8 through an IV, they eat about 11% less food afterward, no matter what they ate before.

In healthy older adults, eating a high-fat diet for 14 days that significantly increases calorie and fat intake does not change the levels of cholecystokinin in the blood after fasting.

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

Eating fewer carbs and more fat—without counting calories—can help people lose about as much weight as eating less fat and cutting calories. This suggests that what you eat might matter just as much as how much you eat.