Most everyone has a body part with which they are unhappy.  For men, it's usually the stomach and for women it's the thighs/hips.  Every year, people spend millions of dollars trying to eradicate problem areas.  They buy specialized exercise equipment that will supposedly turn that problem area into a sculpted thing of beauty.  This is, unfortunately, usually a waste of time and money.

The simple fact is that you cannot spot reduce fat.  If you have a rotund tummy, you can lie on the floor and do crunches/sit ups 24 hours a day and not change the outward appearance of your body in the least bit.  The abdominal muscles that you're working while doing crunches are, indeed, burning calories during exercise.  The problem is that they receive energy through the bloodstream and not from the fat layers adjacent to the muscle. Since the energy is being received from the bloodstream, and not from the underlying muscle, it is not necessary to work the body part that you would like to make slimmer. 

More important than working the area you want to shrink is working on how much food you're consuming.  If you really want to improve the look of your hips or abdominals it is more important to be concerned with the difference between your caloric expenditure and your caloric intake.  If you are eating more calories than you're expending, you will have no significant change in the appearance of your body.

In fact, you can spend the entire day at the gym, working out until you feel like you're going to die. But if you go home and eat as many calories as you burned during the workout, you will likely be disappointed with your mirrored results. *(You will, however, derive significant health benefits from exercise even if you do not lose weight.)

It is also important to note that not all muscles in your body burn the same amount of calories during exercise.  The abdominal muscles, for example, are a relatively small group of muscles and do not burn a significant amount of calories when exercised.  It is far more efficient to exercise larger muscle groups as they will burn more calories.  The muscles of the legs are some of the largest in your body.  If you're truly interested in burning calories (so that you can lose the fat over your problem area – wherever it may be), then focus on exercises that involve the lower extremities.

Getting rid of your problem areas is certainly not easy.  But if you exercise hard and diet properly, you can sculpt your body to a form that will make you happy.