Spot reduction refers to the fallacy that fat can be targeted for reduction from a specific area of the body and that it can be achieved through exercise of specific muscles in the desired area, such as exercising the abdominal muscles in an effort to lose weight in or around one's midsection. Advertisers exploit this concept when advertising exercise-related products.
The scientific consensus among fitness experts and researchers is that spot reduction is a myth. Studies largely show that it is not possible to reduce fat in one area by exercising that body part alone. Instead, fat is lost from the entire body as a result of diet and regular exercise. Muscle growth in the abdominal region does not reduce fat in that region. Instead, being on a caloric deficit is recommended for reducing abdominal fat.
The misunderstanding may be attributed to the firming and shaping effect of muscle hypertrophy. When additional muscle is built, it takes up new space which can briefly compress subdermal fat against the skin until the skin adapts, a larger bulging muscle shape is also more easily seen through the layer of fat on top of it. This can give the illusion of fat being reduced when it has not. For example, triceps hypertrophy firming the back of the arm.