“I can’t lose weight because I don’t have time to exercise.” This excuse no longer works. Just 20 minutes out of your 24-hour day. If you slightly reduce the time spent looking at your smartphone, there is an exercise anyone can do. However, I warn you in advance. As short as it is, this workout will show you a ‘taste of hell’.

It is ‘High-Intensity Interval Training (HIIT)’. Developed to improve the cardiopulmonary endurance of elite athletes, it is now considered the most powerful diet exercise method in the world. Let’s dig into the surprising secrets of why you lose more weight even with shorter exercise times.

1. Fat Continues to Burn Even After Exercise (After-burn Effect)

General aerobic exercise (walking, light jogging) burns calories ‘only during that time’ you are exercising. The moment you step off the treadmill, fat burning stops.

However, HIIT is different. Explosive movements that raise the heart rate to over 90% of its maximum put our body in a state of ‘Oxygen Debt’. Simply put, the body gasps for breath, screaming, “I lack oxygen!” After the workout ends, our body uses immense energy to replenish the lacking oxygen, repair damaged muscles, and cool down the body temperature. This is called ‘Excess Post-exercise Oxygen Consumption (EPOC)’ or the ‘After-burn Effect’.

• Result: Even while you shower, eat, and sleep after exercising, your body continues to burn fat for up to 24~48 hours. This is why HIIT is called the ‘King of Cost-Effectiveness’.

2. Protect Muscles and Shed Only Fat

Long-duration, low-intensity cardio (like marathons) burns fat, but as the time gets longer, our body tends to break down muscle to use as energy. This is also the cause of the body becoming flabby without elasticity after a diet.

On the other hand, HIIT provides short and thick stimulation. This minimizes muscle loss while powerfully striking body fat. Look at track and field athletes. Marathon runners (long-duration cardio) are very thin, but 100m sprinters (high-intensity interval) have muscular, toned bodies. To build the ‘toned and slim body’ we want, we must train like sprinters.

3. Improvement of Insulin Resistance (To a Body That Doesn’t Gain Weight)

HIIT instantly depletes the carbohydrates (glycogen) stored in muscles. The empty muscles suck up sugar in the blood like a sponge to replenish energy. When this process is repeated, insulin function improves, transforming you into a ‘constitution that doesn’t gain weight’ where the same food is used as muscle energy rather than stored as fat.

4. ‘Tabata Routine’ to Start at Home Right Now (The Miracle of 4 Minutes)

I introduce ‘Tabata Training’, the most famous method of HIIT. It is a method of filling a total of 4 minutes by repeating [20 seconds all-out exercise + 10 seconds rest] 8 times.

🔥 Bodyweight Hell Routine (Recommend 4-5 Total Sets)

1. Jumping Jacks: Full body warm-up. As fast as possible!
2. Burpee Test: The devil’s exercise. Targets total body strength and cardio simultaneously.
3. Mountain Climber: Running while prone. Powerfully burns abdominal fat.
4. Jump Squat: Explodes lower body strength to raise heart rate to the peak.

Perform these 4 movements in rotation with 20 seconds of exercise / 10 seconds of rest. If you think, “I feel like I’m going to die”? You are doing very well.

5. Precautions: You Must Follow These

Since HIIT is powerful, the risk of injury is also high.

1. Warm-up is Essential: If you suddenly run a cold engine at full throttle, it will break. You must warm up your body with stretching and light jogging in place for at least 5~10 minutes before the main workout.
2. Do Not Do It Every Day: High-intensity exercise puts great stress on the body. Doing it every day increases cortisol levels, which can actually cause weight gain or injury. 2~3 times a week is sufficient. On other days, do walking or stretching.
3. Caution for Beginners and Hypertensive Patients: For those who don’t usually exercise or have cardiovascular diseases, it can strain the heart. You should lower the intensity at first or proceed after consulting a doctor.
4. No Effect if Done ‘Roughly’: The core of HIIT is ‘All-out’. If you can talk to the person next to you, that is not HIIT. If you don’t pour out all your energy for 20 seconds, it is just a ‘short workout’.

Conclusion: Challenge Your Limits

HIIT is physically hard, but it is an even harder workout mentally. The temptation to stop comes every second. But that time of pain ends in just 20 minutes.

Would you rather walk yawning on a boring treadmill for 1 hour, or burn with heart-bursting passion for 20 minutes and enjoy the pleasure of burning fat for the rest of the day? The choice is yours. Tonight, push yourself to the limit for just 20 minutes. The body in the mirror will remember those drops of sweat.