Blog Fitness Workouts Abs Workouts The 20-Day Abs Challenge: Get Sculpted In Less Than 3 Weeks With This Exercise Routine

The 20-Day Abs Challenge: Get Sculpted In Less Than 3 Weeks With This Exercise Routine

flat stomach workout

The 20-Day Abs Challenge is a great way to tone your abdominal muscles and get that six-pack you’ve always wanted. This challenge includes an exercise routine designed for beginners, which can help tone your stomach muscles and make them more defined.


You might be wondering why we chose just “twenty days” as opposed to 30 or 10 or some other number. Well, there’s no magic number when it comes to losing belly fat and getting washboard abs. It’s all about consistency and being persistent (and eating right, of course). This workout is effective because it works with your body instead of against it. You can adjust the difficulty, and frequency depending on your fitness levels. 

Using weights when it’s a great idea to add intensity to the workout – but always use proper form! Start out lifting lighter, until you’re able to find the proper amount of weight for each exercise; then gradually increase the weight by about ten pounds every week through the 20-day challenge.

There are several different exercises you need to complete to get great gains from this program, but we’ll only cover some important ones. At the end of each workout, you’ll need to perform a short warm-up and a cool down.

Here’s a sample workout set that can be modified to fit your version of the 20 days abs challenge:

  • Medicine slam ball: three sets; ten reps
  • Mountain climbers: three sets; ten reps
  • Russian twists: three sets; ten reps
  • Abdominal crunches: three sets; ten reps
  • Planks: three sets
  • Side planks: three sets; ten reps
  • Don’t forget to rest for 45 seconds between sets and 2 minutes between each exercise

Read More: Planks For Abs: Exercises That Will Set Your Core On Fire

20-day abs challenge

How To Get A Flat Stomach: Understanding Your Abdominal Muscles

The abdominal muscles support the trunk, allow movement and hold organs in place by regulating internal abdominal pressure. The four main abdominal muscle groups that combine to completely cover the internal organs include:

See also
Planks For Abs: Exercises That Will Set Your Core On Fire

Rectus Abdominis

The rectus abdominis muscle runs vertically from your sternum to your pelvis on each side of your abdomen. It is responsible for flexion of the spine or bending forward at the waist. It also helps hold the abdominal wall muscles in place.

Some exercises that target the rectus abdominis as part of a lower belly fat workout include:

20-day abs challenge


Crunches target the upper portion of the rectus abdominis. These are performed while lying on your back, with knees bent and feet flat on the floor. To perform a crunch you need to:

  • Slowly raise your shoulders off of the floor, extending your neck towards your hips until you feel a contraction in your abdomen. 
  • Pause briefly before returning to the starting position. 
  • Do not use momentum by swinging or raising legs; keep both hands at the side and palms flat against the floor. 
  • Be sure that stomach muscles contract during exercise by feeling for them to tighten up, as this ensures an effective workout for those hard-to-reach rectus abdominis muscles. 
  • To add more difficulty to crunches, try doing these exercises using a ball or by adding weight to your torso while doing crunches.

Leg Lifts

Leg lifts target the lower portion of the rectus abdominis muscle. To perform these exercises for lower abs, you have to:

  • Lay flat on your back, knees bent and feet flat on the floor, hands behind the head without touching ears. 
  • Raise legs upward until they are almost parallel with the floor and in line with shoulders.
  • Hold for one second, then return down slowly to the starting position and repeat 10-15 times. 
  • Be sure to contract your stomach muscles to effectively work the rectus abdominis muscle.
See also
How To Get A Smaller Waist: Tips For Burning Belly Fat And Toning Abs

20-day abs challenge

Mountain Climbers

Mountain climbers target the upper and lower rectus abdominis muscles and are done while on all fours. To perform mountain climbers you have to:

  • Start in a high plank, with your palms flat on the floor, hands shoulder-width apart. 
  • Raise the opposite knee towards the chest by bending the leg at the knee until the knee is in line with the hip, then straighten the leg back to the plank position. 
  • Simultaneously do the same motion with your left leg, which means that your right leg should be lifted off of the ground as your left leg goes forward. 
  • Continue alternating legs quickly for the duration of exercise. 
  • Make sure to keep your core engaged and back flat throughout. If you have to slow down to maintain form, that’s fine.

Flutter Kicks

Flutter kicks target the lower portion of the rectus abdominis muscle. These are done while lying flat on your back and engaging your core. To perform flutter kicks you need to:

  • Lie down on your back with your legs extended, arms by your sides. Using an exercise mat will help reduce the pressure on your lower back.
  • Press your lower back into the mat and tuck your pelvis. This will help to engage your core.
  • Lift both legs off the mat, about 6 inches from the floor. You should not feel pain in your lower back.
  • Lower one leg toward the floor; as this leg gets close to the floor, lift the other leg.
  • Continue scissoring your legs by slowly switching them up and down.
  • Be sure not to swing or use momentum by lifting your hands during movement (keep both hands at sides).

Lean and toned up body isn’t just a far-fetched fantasy. Check out the BetterMe app and watch it propel your weight loss journey into high gear!

See also
28-Day Abs Challenge That Will Rock Your Core And Leave No Trace Of Belly Fat

External Oblique Muscles

The external oblique muscle group lies on the sides of your abdomen and is responsible for lateral flexion or bending sideways at the waist. It also plays a role in drawing the torso forward when you bend at the hips

Anything that causes increased pressure within your abdomen can weaken these muscles, causing them to bulge out. Continued bulging due to weak abdominal muscles can lead to postural defects such as protruding stomach. The main cause of this weakness is poor diet and lack of exercise, especially when coupled with high-fat diets that stagnate intra-abdominal blood flow.

20-day abs challenge

Internal Oblique Muscles

The internal oblique muscle group lies beneath your external oblique muscles and allows you to rotate from side to side. The primary function is trunk rotation or twisting at the waist.

In many cases, this muscle group becomes enlarged because it is constantly contracted to stabilize a weaker exterior oblique pair and reduce pressure within the abdomen. 

This causes an unsightly protrusion on the sides of your abdominal region referred to as “spare tire” by some or sarcopenic obesity by others (2). If you are interested in increasing your stability at your core and diminishing fat deposition around your midsection, you should perform weight training exercises that work for the internal oblique muscle group.

To train your obliques in all the ways they function, you’ll need exercises that use uneven loads, instability, or rotation.

Some exercises that target the obliques, and should be part of your belly fat workout, include:

Side Planks

This exercise primarily targets the obliques. However, it also works the core, hips, and shoulders. To do a side plank, you have:

  • Start on your side with your bottom forearm directly below your shoulder. Your feet should be stacked on top of each other. 
  • Engage your core and raise your hips. Your body should be in a straight line from head to toe. 
  • Hold this position for 30 seconds.
  • Let your hips drop, and repeat. 
  • Switch sides and repeat.
See also
Belly Fat Workout At Home: Lose Belly Fat At Home With These Simple Yet Effective Exercises

Read More: Are Planks Good For Abs? The Truth About This Popular Workout

20-day abs challenge

Russian Twists

The Russian twist is a great exercise to work your obliques and build abdominal strength. 

  • Sit on the floor with both legs straight. Bend your knees at a 90-degree angle, keeping them together and feet flat on the floor. Your back should be upright and arms extended in front of you. 
  • Extend your arms out to the sides, rotating them as far as possible before bringing hands back together in the center or clasping them behind your head. Be sure not to jerk forward when swinging arms backward or arch your lower back (you may want a spotter for balance at first). 
  • Hold for 30 seconds before repeating the exercise. Repeat 10 times per side if performed correctly. The difficulty may be increased by adding weights held with arms down during the rotation. 

Transverse Abdominis Muscles

The transverse abdominus muscle is located beneath your external and internal obliques and supports your abdomen during movement by constricting around the organs within your abdominal cavity. It runs horizontally underneath both layers of outermost abdominal wall skin – supporting the core structure while maintaining pressure on internal organs, such as the intestines, kidneys, and liver. This is sometimes referred to as a girdle muscle because it holds everything together (1).

As this muscle group becomes stronger, you can perform more demanding physical activities without sacrificing stability at the core of your body. Performing basic standing abdominal crunches can tone this muscle group, which in turn, helps to minimize fat deposition around the middle of your body (1).

20-day abs challenge

Exercises that target your transverse abdominis muscles as part of a flat stomach workout include:

See also
Types Of Crunches To Boost Your Abs Workout Routine

Medicine Ball Twists 

  • Stand with your feet shoulder-width apart, knees slightly bent, and legs facing forward. 
  • Hold a medicine ball (weighted if possible) in both hands at chest level. 
  • Slowly move the ball from side to side several times, then return it to the starting position. 
  • Repeat this for two or three sets of 10–12 repetitions, to begin with, increasing as you become stronger.

Transverse Abdominis Push-Ups 

  • Start in a push-up position with hands directly beneath your shoulders and your core muscles engaged. 
  • Lower yourself down slowly until only your toes are touching the ground, and raise yourself back up again. 
  • This exercise works best if you do each repetition more deliberately rather than rushing through them quickly, which can cause you to use momentum rather than core muscles to complete the movement.

Other core strength exercises such as lunges, bridges, and bicycle crunches also engage your transverse abdominis muscles.

The Bottom Line

The 20-Day abs challenge is a great way to challenge yourself and get fit quickly. A workout like this will help you shed the built-up fat in your abdominal area and make it easier to maintain your figure.

This isn’t a sprint, so be sure to give yourself enough time at the end of each month’s twenty-day challenge to motivate for another one!



This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!


  1. Comparison of the recruitment of transverse abdominis through drawing-in and bracing in different core stability training positions (2019,
  2. Sarcopenic obesity – definition, etiology and consequences (2009,
150 million people
have chosen BetterMe

I love this app!

I love this app! I love that it has so many different workouts that I can choose from with all different durations that I can choose from in order to achieve my goals. I recommend this app to everyone and anyone.

The app is easy to use but effective…

Saira H.
The app is easy to use but effective and the workouts are great! You will feel it and see results, the goal is to get 1% better everyday!!!

Exercises are simple but effective

Oudeen H.
All the exercises were manageable and were effective. It's amazing how stretching is key way to exercise.