Q: Why is the concept of spot reduction considered a myth?

A: Unfounded programs and devices that purport to achieve spot reducing have become a multi-million dollar industry in a country where the health and aesthetic disadvantages of obesity are well recognized. Numerous scientific studies, however, cast doubt on the validity of spot reduction—the process of selectively taking inches off the waist, thighs or buttocks.

In one study, for example, the circumferences and fat deposits in the arms of high-level tennis players were compared. The investigators proposed that if spot reduction worked, the playing arm of a tennis player should have considerably less fat than the inactive arm. This prediction, however, was not the case. Despite the fact that circumference measures in the playing arms of the athletes were greater due to more muscular development, skinfold thickness measures revealed no difference in fat deposition between the two arms.

Arguably the most compelling evidence refuting the myth of spot reduction comes from a study conducted at the University of Massachusetts in the mid-1980s. In this investigation, 13 male subjects participated in a vigorous abdominal exercise training program for 27 days. Each participant in the study was required to perform a total of 5,000 sit-ups over the course of the research project. Fat biopsies were obtained from the subjects' abdomens, buttocks and upper backs before and after the exercise program. Contrary to what spot-reducing proponents would have you believe, the results of the study revealed that fat decreased similarly at all three sites—not just in the abdominal region. These findings may help explain one reason why spot reducing sometimes appears to work. If the caloric expenditure is sufficient enough, it will cause fat from the entire body to be reduced, including a particular target area. Although fat is lost or gained throughout the entire body, it appears that the last areas to become lean tend to be those areas where an individual tends to gain fat first. In most men (and some women), the abdominal region is the most difficult area to trim, while the hips, buttocks and thighs tend to be the trouble spots for most women (and some men).

Source: Bryant, Cedric X. ACE FitnessMatters, January/February 2004.