"Abdominal training should not be in your vocabulary, and you should definitely never take a half-hour abdominal class at your gym multiple times per week. While you may feel inclined to train your abs so that they’re toned with little belly fat, these classes are not the correct way to make those improvements. Remember that strength training not only increases your muscle strength but also how large your muscles grow. The more you train your abdominal muscles, the larger they will get.
You are actually adding size to your waist, but not targeting belly fat. Belly fat decreases when you reduce your caloric intake and burn more calories than you take in. Your body doesn’t automatically trigger a fat-burning mechanism in certain regions when you begin training those muscles. Fat burning is part of your overall metabolic process, and for women, it often begins from the top down. So, your belly will likely be one of the first regions on your body to burn fat, but it won’t happen from doing abdominal exercises in excess. This “spot reduction” myth has been debunked in research. You can’t train a certain body part and expect it to accelerate fat loss in that particular region."
Strong Curves, Chapter 7