Can You Crunch Your Way to a Flat Stomach?
For years, ab-crunching moves, from curls to sit-ups, have been the holy grail of stomach-flattening exercises. Media has flamed the hype, reporting on the hundreds of crunches that various celebrities do — presumably, the secret to their photogenic physiques.
But is it the crunches themselves that shrink the width of your midsection? Can they actually reduce belly fat? Read on for more info, but here’s a hint: no.
Are Crunches a Good Flat-Stomach Workout?
The crunch is a floor exercise that targets your rectus abdominis (AKA six pack) muscle. Here’s how it’s done:
• Lie on your back with your knees bent, feet flat, and your fingertips touching your head lightly behind your ears.
• Keeping your lower back pressed against the floor, contract your abs to bring your ribs closer to your hips and to raise your head and shoulders slightly.
But the real question isn’t how to do them, the question is: should you do them?
Do Crunches Spot-Reduce Stomach Fat?
One misconception about crunches is that they torch stomach fat — unfortunately, they don’t.
That burning sensation you feel on your 50th crunch is not the burning of fat, but rather the fatiguing of the abdominal muscles below the fat layer, says Chris McGrath, M.S., C.P.T., founder of Movement First and senior advisor to the American Council on Exercise (ACE).
“Doing an exercise to take fat off from a specific area of the body simply doesn’t work,” he says. “If it did, chewing gum would help people lose fat from their face.”
One classic abs exercise study in the journal Research Quarterly for Exercise and Sport had young men work up to 600 sit-ups every day. After nearly a month of this regimen — more than 5,000 sit-ups later — there were no changes in fat cell size, waist size, or fat-fold thickness at the waist.
Another study in the Journal of Strength & Conditioning Research had men and women do seven different abs moves, including crunches — two sets of 10 reps each. The subjects performed these moves five days a week for six weeks. By the end of the study, there was no difference in their waist sizes or in the percentage of fat in their torsos. (That doesn’t mean there was no benefit — the subjects did increase muscular endurance in their cores.)
Best Exercises for a Flat-Stomach Workout
Since you can’t spot-reduce fat, you need to perform workouts that burn it efficiently all over the body, including your stomach.
So what’s the best form of exercise for this goal? The one that you’ll do consistently. It really is that simple.
Science regularly flops back and forth in its endorsement of cardio or strength training for fat loss, but nearly all studies suggest that either one can aid weight loss when paired with a healthful diet — and their effects are even more powerful when they’re combined into a comprehensive fitness program.
Indeed, a study in the American Journal of Physiology found that cardio plus resistance training is more effective at burning fat than cardio alone.
In short, follow the government’s physical activity guidelines consistently, and you’ll likely appreciate the results you see in the mirror, as well as the strength, power, and energy you bring to everyday life.
Can Crunches Be Harmful?
Performed incorrectly, crunches can strain the spine and increase the risk of back pain. But when done with proper form, they can be a powerful tool for targeting your abs and strengthening your core. So follow the exercise instructions above, and avoid these common form flaws:
- Raising your shoulders too high.
- Rounding your lower back.
- Pulling on your head. (Don’t interlock your fingers behind your head—lightly touch your fingertips to it behind your ears.)
If you want a nearly failsafe way to hammer your abs while minimizing the stress on your spine, you can perform a variation of the crunch called the “McGill curl-up” (pictured above) after its creator, renowned University of Waterloo spine researcher Stuart McGill.
- Lie on your back with your left leg extended, your right knee bent, and your right foot flat on the floor.
- Place your hands under your lower back, palms down. This is the starting position.
- Keeping your lower back stationary, engage your core, lift your head and shoulders off the ground.
- Pause, return to the starting position, and repeat.
“This move involves more tightening of the muscles with minimal spinal movement compared to the traditional crunch,” explains McGill. And in so doing, can help reduce your risk of pain and injury.