Spot reduction refers to the belief, long viewed as a myth, that fat can be targeted for reduction from a specific area of the body. There is a common view, although many people believe that view is misguided, that it is possible to achieve spot reduction 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 play on this concept when advertising exercise-related products to gullible people.[1] However, many fitness experts do not believe it is possible to reduce fat in one area by exercising that body part alone.[2][3] Instead, fat is lost from the entire body as a result of diet and regular exercise.[3] Muscle tone in the abdominal region does not reduce fat in that region.[4] Instead, being on a caloric deficit is recommended for reducing abdominal fat.[5]
The misunderstanding may be contributed to by 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.
A 2006 study published in the American Journal of Physiology [6] uncovered some interesting results, which seem to indicate that spot-reduction may in fact be possible, although to what degree is unclear. In the study, conducted at the University of Copenhagen (Denmark), scientists had male subjects perform single-leg extensions with light weight for 30 consecutive minutes. The researchers then measured the amount of blood flow to the subjects' subcutaneous fat cells (those under the skin) in both the exercising and resting thighs, as well as the amount of lipolysis (release of fat) from those fat cells.
The scientists discovered the exercising leg experienced a significant increase in blood flow to and lipolysis from the subcutaneous fat cells, compared to the resting leg. During exercise, the fat cells surrounding the trained muscle released more fat into the blood, meaning a greater quantity of fat from the targeted area is released into the body to be used as fuel. The study suggests that when you exercise, you do burn bodyfat preferentially from the area you're training.