GI Joe is correct; and I would (should) add that you can even include weight/resistance training (and should, because nothing burns fat like an amped up metabolism and new muscle, and LADIES, you will NOT get bulky, you don't have the hormones or "design" for such an outcome
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Obliterate that word, "toning," from your vocabulary, it is obsolete in its current usage, as you either build muscle, or oxidize (lose/burn) fat on top of it, there is no "toning" the muscle. You can't change the shape of a muscle, only change the size, increasing the size of the muscles' fibers, or allowing them to shrink through inefficient dietary choices (very low calories/low protein) and omitting sufficient workload (not using your muscles, you don't use it, you lose it). Another scientifically known concept is that simple carbohydrates, like crackers and white flour products, candy etc...are a common cause of abdominal/visceral fat growth and composition (technically the "beer belly" term comes from the empty calories in beer creating this image). But with this disease (and this still floors me, my mouth dropped in 2006 when the nurse gave me the literature on Crohn's) simple carbs are often recommended, hence our need to be extra vigilant and cautious.
A major problem within the obesity epidemic (other than food overindulgence) is the lack of muscle to combat it. A "normal" looking person can add 15 pounds of muscle (would take perhaps 15 solid weeks for a male, or a year or so for a female, biologically and statistically) and you'd never think they looked "too muscular" or "ripped" (you might not even notice with their clothes on) but those 15 lbs of muscle would comprise an advantageous weapon against fat gain and towards fat loss, and allow you to eat more food while burning it off. Since each pound of muscle is about 35-40 calories a day in expenditure to just exist (doing nothing at all), then you're looking at that person, 15 lbs. of muscle later, burning about 525-600 calories a day more than before, even when sitting around all day if they so choose. They have more they can eat, thus they have more "indiscretions" to take part in, or, they can do little to no cardio and just keep lifting weights moderately while modulating diet alone to lose more fat.
Working your abdominal muscles would prove to increase core stability and performance (I don't remember where this was discuss here recently, I'm blanking, but it was with Shantel a couple months ago?), but will do very little to burn fat or shape your midsection.
