What Do Crunches Do for Your Body?

Doing stomach crunches is a time-honored way of strengthening your core. It's also a classic no-equipment resistance move that you can do virtually anywhere. But if you have visions of a magically flat belly after doing crunches for abs, you may be in for a disappointment.

Unfortunately, even if your stomach is your only problem area, traditional crunches for abs — or reverse crunches and bicycle crunches, for that matter — won't achieve that mythical "spot reduction" on your belly. It's not that crunches are pointless, given how important strengthening ab muscles are. But crunches don't address the fat itself. For that, you'll need to take a whole-body approach with cardio, diet and strength training.

Once you're ready to work on muscle definition, it's important to remember that crunches alone can't create that toned look on your entire belly and waistline area. The American Council on Fitness reminds core enthusiasts that the basic crunch only works on the rectus abdominis, also known as the "six-pack muscles."

Traditional crunches don't work your obliques, the muscles located at the sides of your torso. For those, you'll need to add variations like oblique crunches. Or you might opt for single exercises like the plank, which works more core muscles, along with back, shoulder and leg muscle groups.

While you can't magically target your belly fat alone by doing crunches for abs, working them into your fitness plan can be part of a whole-body, fat-burning strategy. Mayo Clinic notes that muscles burn more calories at rest than fat cells do. While cardio and dietary changes are important for fat-burning, building muscle mass in your core will also contribute to overall increased metabolism.

As a part of an overall strategy of increasing metabolism, Mayo Clinic recommends strength training at least twice a week. Along with stomach crunches, equipment-free strength training can include pushups, squats and planks.

Read more: The Best Waist Trimming Exercise Without Any Equipment

Your abs are part of your core, which are the major muscle groups of your torso. That's why crunches, reverse crunches and other abdominal workouts can be a part of strengthening your core, as Harvard Health Publishing points out. But for whole-core results, combine them with moves like squats, lunges and planks.

A strong core helps prevent and reduce low back pain. Other benefits of a strong core include improved posture and better stability. That improved balance is invaluable for everything from preventing serious falls to improving your paddleboarding.

Read more: 10 Yoga Poses to Strengthen Your Abs

Core muscles additionally facilitate the reaching and twisting moves needed for a wide range of cardio activities, including paddling, golf, tennis, swimming and running. They also help reduce aches and pains sometimes connected with the chores of life such as emptying the dishwasher and vacuuming.

Of course, keeping backaches at bay and good posture is important. But on a shallow note, it's natural to wonder how much those crunches for abs actually show up to the naked eye. After all, the "six-pack" itself refers to the same muscle group, the rectus abdominis, that stomach crunches engage.

The visual impact of your crunches depends on how much fat sits above those ab muscles. If you don't have much belly fat to begin with, or if you're also losing fat through diet and cardio, your strength training will become more apparent. But you'll definitely need to work off the body fat before the muscle definition from all those crunches, reverse crunches and bicycle crunches becomes apparent.