Invisible fat refers to fat that cannot be easily seen and is impossible to separate from food, such as butter that has been baked into a cake or the natural oils found in nut butters. A visible fat such as olive oil may be absorbed during cooking and become invisible.
Visible fat, such as excess fat on a cut of meat or margarine spread on a slice of toast, can be removed or is more easily avoided than invisible fat. Even after trimming the visible fat from a cut of meat, the lean meat still contains some fat. This is the invisible fat that cannot be removed.