Here's the thing - you cannot pick a particular site of your body to lose weight from. This is a misconception known as "spot reduction" which has no scientific evidence to support the notion that one can target an area of the body to lose fat tissue from.
This means that in order to tone your tummy area, an excess number of crunches (or other abdominal exercise) will not necessarily encourage fat metabolism from this area. You will however need to continue focussing on weight loss through nutritional and exercise implementation. Eventually, you will see a reduction of body fat around the waist area.
Of course toning comprises both of fat loss and muscle gain. So in order to assist in muscle development around the abdominal area, you will also need to implement a resistance training regime which will be conductive of rectus abdominus development. Such a program would incorporate crunches or similar exercises.
