No. You can not spot train to loose belly fat, you have to loose it all over. Cardio workout 4-5x/wk mixed with 1-2 days of strength training ( including crunches) is the best way to loose weight and tone up.
Spot fat loss does . Not occur naturally. By losing weight in general some will probably be abdominal fat. But, we don't get to choose what area of body fat is lost from. Eat healthy ; be physically active. Calories burned must > those consumed. The ab crunch machine may tone abs' but won't remove the fat.