Will 100 Crunches A Day Do Anything? A Certified Personal Trainer’s Answer

Is doing 100 crunches a day worth it?

We hear frequently that ab exercises like this are the best way to flatten and tone your stomach. And doing more is better, right?

I’m a professional trainer and coach. Unfortunately, I still see posts suggesting that crunches alone will melt away belly fat. I compare this to a laser pointer that keeps a cat chasing something it cannot physically catch.

Doing hundreds of crunches is not as important as making healthy dietary choices or having a well-rounded training routine with the right balance of cardio and strength training.

Achieving visible abs requires low body fat. While crunches can burn calories like any other exercise and strengthen the abs, they cannot reduce stomach fat.

However, this doesn’t mean you shouldn’t do them. Doing 100 crunches a day can give you a firmer midsection, and has many other benefits. So, put your workout gear on, grab your mat, and let’s get crunchy!

What are crunches?

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Crunches are an exercise that works your rectus abdominis, called the “six pack” muscle, which runs along the center of your midsection.  It involves flexing the spine, mimicking a crunching motion. 

You start by lying on your back with your knees bent and feet planted into the ground. Then, you lift your shoulders off the floor while tucking your chin in, keeping your lower back in contact with the floor.

Incorporating them into your strength training routine and healthy lifestyle can result in fat loss, but crunches don’t just burn belly fat. Still, doing 100 crunches a day for a month can be a fun challenge to get moving.

Common Types of Stomach Crunches 

Adding different types of crunches to your workout routine can prevent training monotony and work other abdominal muscles in your core. It can result in a firmer, stronger core, reducing your risk of injuries and lower back pain. 

In this section, I am going through different abdominal crunch variations and how to perform them correctly. 

1. Basic Crunches

Method: 

• Lie down on your back with your knees bent and feet on the ground hip-width apart. 
• Place your arms across your chest, behind your head, or wherever comfortable.
•  Inhale and engage your abs.
• As you exhale, lift your upper body – head, back, and shoulders off the ground while keeping your head and neck relaxed.
• Breathe in and return to the starting position.

2. Bicycle Crunches

Method:

• Lie on your back and bring both knees off the ground at 90 degrees. 
• Bring your right elbow to the left knee while straightening your right leg.
• Return to the starting position and then repeat on the other side. This time, bring the left elbow to the right knee while straightening the left leg. 
• Repeat for the desired reps and sets. 

3. Reverse Crunches

Method:

1. To start, lay on your back and bend your knees at 90 degrees with your feet on the ground. 
2. Put your hands underneath your bum to make the exercise easier and avoid overextension of the lower back.
3. Exhale, bring the knees in toward the torso, and push the hips toward the ceiling. 
4. Inhale and return to the starting position without your feet touching the ground.
5. Perform 15-20 reps. 

4. Vertical Leg Crunches

Method:

1. Lay on your back with both of your legs straight up.
2. Place your hands beside your head.  
3. Curl your upper body by lifting your shoulder blades and head off the ground. 
4. Make sure your legs remain straight and up.
5. Return to the starting position by putting your upper back and head back on the ground. 
6. Exhale as you curl and inhale on the way back to the start. 

5. Oblique Crunches

Read More: 20 Best Oblique Exercises

Method:

• Begin by lying on your side with knees bent.
• Rotate your torso slightly to face up and to the side. Lift your legs a few inches off the mat. 
• Place your top hand behind the head by bending the elbow.
• Bring your legs up toward your elbow, elbow to your knee, while simultaneously crunching sideways.
• Keep your head/neck relaxed.
• Exhale as you lift and inhale as you return to the start.
• Repeat for 10-15 reps.

How many crunches a day?

How many crunches you should do a day depends on your current fitness level, past injuries, your fitness goals, time, and overall exercise routine. 

There is no golden rule about how many crunches you should do, as long as you maintain good technique and engage your core properly.

For example, after pregnancy the muscles are stretched. Some women find it difficult to engage their abdominal wall. This means their routine requires more attention to core activation, rather than just crunching blindly.

Also, if you are a beginner, you should gradually build up the amount of crunches you do daily. This can reduce your risk of injuries and soreness, so you can continue doing them.

Start with two to three sets of 15-20 reps and increase the reps weekly as you get stronger.

How many crunches a day to get abs?

I thought you’d ask! I could throw a number out of nowhere, but that would be wrong. 

There isn’t a specific number of crunches that will get you abs. However, as long as it challenges you, it will change you.

As I mentioned, your current body fat percentage will highly determine how visible the result will be. People with low body fat may see some results from doing 100 crunches a day. Those with high body fat may be disappointed.

Research shared by the National Library of Medicine finds that performing abdominal exercises increases muscle endurance, but makes NO DIFFERENCE in the reduction of abdominal fat!

Is 100 crunches a day good?

It can’t hurt, but my professional advice is not to solely focus on crunches. Instead, focus on different planes of movements:

• Twisting: Russian twists, standing barbell twists 
• Bracing: Planks, side planks
• Anti-rotation exercises: Sledgehammer woodchops, Pallof press
• Lateral movements: Side bends, heel touches 
• Abs exercises (sagittal plane) : Crunches, sit-ups

These, combined with strength training, cardio, and a healthy diet will get rid of the layers of fat hiding your abs from you!

100 Crunches a Day Benefits

Related: Full Body Workout Every Other Day

So, we know that crunches won’t give us a fat-free washboard stomach. However, there are still benefits to including them in your routine. Here are the best:

Toned abs

Performing crunches consistently, combined with a well-rounded fitness and diet plan, can tone your abs. 

Core strength

Crunches can strengthen the abs by contracting (training) them over and over. 

Improved posture

The rectus abdominis play a crucial role in core stability. It helps stabilize the lower back/spine during overhead movements, protecting it during deadlift or carrying. 

It also assists in breathing, flexing the spine, and lifting your pelvis. All this is important to maintain a good posture and avoid injuries.

Improved athletic performance

As crunches play a crucial role in core stability, working with other muscles can improve power transfer and enhance athletic performance.

Increased flexibility

Crunching involves spinal rounding, which can improve spine flexion to some extent. 

Prevents boredom and plateau 

You can do different crunch variations that can work different parts of your core. For example, bicycle crunches work your obliques while reverse lunges work the lower part of your abs.

This can keep challenging your core on different levels and progress your results. You can also do them anywhere, which makes it easier for those without gym membership!

Will 100 crunches a day do anything?

Yes they will! You will increase muscle endurance and ab strength by performing 100 crunches a day. Your abs will get more firm.

If you already have pretty low body fat around your midsection, you may even start seeing those “11” shaped abs, if not the six-pack.

100 Crunches a Day for a Month – Results

Doing a month-long challenge is a great way to keep yourself competitive and get exercise for 30 days straight without burning out. 

However, it is essential to know what you can or can’t expect from doing 100 crunches daily for a month. Pay attention as I will break it down for you below!

• Week 1

Your first week may be a struggle. You may need to take some breaks after 15-20 reps. 

But don’t worry – by the end of the first week of completing 100 crunches daily, you will notice the exercise getting easier. This is proof your abs are getting stronger. 

• Week 2

Your abs may feel more dense when you poke them. 

Your strength continues to increase and by the second week, you will be able to do more crunches than the previous week. 

You may also feel improvement in your posture, which is amazing! 

Note: Your enthusiasm may start to wear off now, but this is when you need to push the hardest and carry on.

• Week 3

If you’ve committed to any calorie restriction or a healthy diet plan, your upper abs may have started to appear by now. Your strength and muscle endurance skyrocket, and 100 crunches becomes achievable. 

• Week 4

The results are becoming clearer by now! The challenge has become a habit, almost your second nature. Your abs may even be visible and you are looking for your next challenge, because you’ve become UNSTOPPABLE!

NOTE:

You may have seen some impressive before-after pictures on social media, saying it’s from crunches.

I am not saying it’s not possible. It may be for someone with superman-like genetics and a good starting shape. But in reality, we don’t really know if that person is committing to any dieting and other workout regime, so be realistic. 

Try them, monitor your results, and have fun without any unhealthy expectations! 

Will 100 crunches a day give you abs?

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Very unlikely!  

To get visible abs, you need to burn the layer of fat on top of the muscle, along with strengthening the abs that crunches are good for. 

Let me explain how your body burns fat.

Our body burns calories! Different types of exercise have different burn different amounts of calories: 

• Resting calories: 

Our body burns calories to function, like breathing, digesting, maintaining body temperature, etc. These are called resting calories (BMR – Basal Metabolic Rate). 

• Non-exercise activities

We burn these calories to move, fidget, stand, bend, etc. This is why how sedentary you are during the day is very important. 

For example, a waitress burns far more non-exercise calories than someone working in an office.

• Exercise

Exercise requires more fuel, which your body gets from fat and carbs. 

You are increasing your heart rate and your body temperature rises, which your body tries to regulate. This is why adding strength training and cardio into your routine, along with crunches, is important. 

The metabolic effect of these exercises is higher to stimulate hormones, oxidize fat (burn) for energy, and regulate blood sugar levels.

Crunches alone don’t require much heat and energy (low energy expenditure), so the fat burning effect of this single exercise is very low. That means the chances of getting abs is lower (as fat covers the abs). 

So this answers the question: 100 crunches won’t give you abs, especially if you don’t focus on burning the fat that covers the abdominal muscles.

Crunches vs Sit Ups 

	Crunches	Sit-Ups
Muscle Activation (muscles worked)	Rectus Abdominis, external obliques, transverse abdominis	Iliopsoas (hip flexor muscles), rectus and transversus abdominis, internal and external obliques
Range of Motion	Small range of movement. The lower back remains in contact with the ground, only the shoulder blades and head lifts off.	Higher range of movement, because the torso is moving up to a seated position.
Injury Chance	Lower risk of injury due to the small range of movement. Although neck strains can occur when doing it incorrectly.	Higher risk of injury on the lower back, because of the higher range of movement. It also requires a stronger core, making it more difficult for those with lower back pain.
Difficulty Level	Beginner friendly.	Moderately challenging. Requires more core strength to perform.
Variety	Moderate Variety: Oblique Twisted Weighted Reaching	Wide variety:  Decline Weighted Butterfly Banded Twisted

Pro Tips for Making Use of the 100 Crunches a Day Routine

Start Slow

Don’t get frustrated if you can’t do 100 crunches a day back-to-back. It’s normal, especially if you don’t do them too often. 

Start slow and gradually increase the reps. 

Use Proper Form

Using proper form can keep you away from injuries and lower back pain. It’s key to successfully completing your 100 crunches a day for 30 days challenge. 

Listen to your body, if you need to stop and rest do so!

Mix It Up

Different crunches can work different muscles. Performing a range of variations can give more definition to your core and strengthen different core muscles, improving posture and reducing risk of injuries. 

Use a Mat

No one likes the feeling of bone on the floor. Protect your spine and use a soft mat!

Combine with Cardio and Strength Training 

If you want visible abs, burn the layer of fat on top of it. Add crunches to your strength training routine and top it off with a cardio workout.

This will melt the fat away!

Fuel Your Body

It must be said that abs are indeed made in the kitchen. A healthy diet will help you carve out those abs as well as keep heart disease and other illnesses away.

Conclusion

Doing 100 crunches is a great way to stay consistent and move daily. They also strengthen your abs, give you a firmer midsection, prevent injuries, and improve your posture!

However, while crunches have so many benefits, crunches alone don’t burn belly fat.

To get six-pack abs, you will need to lower your body fat percentage. This can be done by incorporating crunches into a well-rounded strength training routine and healthy diet.

If you decide to jump on a 100-day crunch challenge, make sure you show us your results. We would love to hear about all the benefits you gain from 100 crunches a day!

Frequently Asked Questions