Does Your Stomach Bulk Up When Doing Crunches?

If you're hoping to tone and slim your stomach, you might start doing crunches to achieve your goals. Crunches, however, are only one part of the recipe for a slim stomach -- if you don't incorporate aerobic exercise to reduce fat, your stomach could actually bulk up as you build muscle under a layer of fat.

Spot reduction is not a realistic weight loss goal. If your weight loss plan only consists of crunches, you'll be disappointed because your stomach won't slim down. If your belly is too large, fat is likely the culprit -- not too little muscle. If you want to slim your stomach, you'll need to do aerobic exercises such as cycling, running or jumping rope. You'll also need to burn enough calories to reduce fat throughout your body. One pound of fat is equal to 3,500 calories, and a healthy diet and exercise program usually results in a pound or two of weight loss per week.

Even if you build lots of healthy muscle tissue by doing crunches, the muscles won't be visible under a layer of fat. In fact, building a lot of muscle without shedding fat can actually make your stomach look bigger. The muscles will only become noticeable after you've shed some fat in your midsection. If your stomach muscles are getting stronger but your waistline is also getting bigger, crunches could be part of the problem.

To get rid of excess fat around your midsection, start with a cardiovascular workout routine. The U.S. Centers for Disease Control and Prevention recommends 75 minutes of vigorous aerobic exercise each week, or 150 minutes of moderate-intensity exercise such as walking. MayoClinic.com, however, points out that most people need about 300 minutes of cardio per week to lose weight. A healthy diet also plays an important role. Cut out unnecessary calories in the form of sugary snacks, sodas and empty calories such as potato chips and focus on lean, healthy foods such as fish, fruits and vegetables. If you're hoping to build muscle in your stomach, get plenty of protein. Adult women generally need about 46 g a day, while men require around 56 g.

As you slim down your stomach, you may still want to build muscle tissue to achieve defined abs. The American Council on Exercise conducted a study which found that crunches on an exercise ball are one of the most effective ab exercises. The bicycle crunch was also highly effective. The captain's chair -- during which you sit in a chair and use your abs to lift your torso and legs upward -- also ranked high.