The Truth of the Matter: Crunching builds and tones some of the ab muscles, which can help you to burn fat quicker, however, crunches alone are not going to remove that layer of fat fondly known as a ‘spare tire’. 

It's just not possible to isolate a single area of your body to workout. Working out the abs should include the transverse abdominus, obliques, all the muscles that wrap around your midsection. Basic crunches only target a small area. To see the best results, choose a well rounded core workout and complement it with cardio and  a solid nutritional plan. Activity, including cardio burns fat. Paired with the strength training that is chiseling out those abs of steel, you should burn that layer of fat off in no time!