Spot Reduction Myth
Contrary to what the info commercials suggest, there is no such thing as spot reduction. Fat is lost throughout the body in a pattern dependent upon genetics, sex (hormones), and age. Overall body fat must be reduced to lose fat in any particular area. Although fat is lost or gained throughout the body, it seems the last area to become lean or the first area to get fat is the midsection (in men and some women) and hips and thighs (in women and few men). Sit-ups, crunches, leg-hip raises, leg raises, hip adduction, hip abduction, etc. will only exercise the muscles under the fat.
Incidentally, fat is also stored under the abdominal muscles and around the intestines and other organs. This can contribute to the "pot belly", pushing the abdominal muscles and the overlying fat outward. This "apple shape" fat distribution has greater health consequences than the lower body "pear shape" fat distribution.
From www.exrx.net