Yale Scientific explains that targeted weight loss is not considered possible according to studies in 1971 and 2007. However, losing weight shrinks the fat cells all over the body, resulting in slimmer ankles.
According to Yale Scientific, the University of California conducted a study in 1971 on tennis players to test the validity of the concept of spot reduction. Because tennis players use their dominant arm much more than their other arm, if spot reduction were possible, there should have been thinner layers of fat on their dominant arm. However, when the researchers measured the players' arms, they found no significant difference.
Yale Scientific also states that the University of Connecticut conducted a similar study in 2007 with participants in a 12-week training program. Each participant's dominant arm was selectively exercised. MRI scans of the participants' arms before and after the training program showed that fat loss was generalized in both arms and did not occur only in the exercised arm.
Wikipedia states that many fitness experts do not believe reducing fat in one area alone is possible. The entire body loses fat all at once as a result of regular exercise and a healthy diet. For example, muscle growth in the abdomen does not reduce belly fat.