Afterburn Effect (EPOC): How It Works, Best Workouts & How Many Calories You Really Burn

In simplest terms, the “afterburn effect” essentially means the calories you continue to burn after exercising. While many people primarily pay attention to the amount of calories they burn while running, cycling, swimming or lifting weights, there’s a whole other important component to calorie-burning that you might be overlooking.

That’s because our bodies actually use up extra energy (calories) after certain workouts to help us recover, cool down and deal with the hormonal changes that the exercise produces. The scientific name for this process is excess post-exercise oxygen consumption.

What does the research we now have available regarding benefits of the afterburn effect mean for the future of your workouts? If you properly plan your exercise routine so you do the right types of high-intensity workouts several times a week, you’ll gain the ability to burn more fat in less time.

Sound too good to be true? Here’s what this phenomenon is all about…

What is the afterburn effect?

The afterburn effect, scientifically known as excess post-exercise oxygen consumption (EPOC), is the process where your body continues burning extra calories after exercise while it restores oxygen levels, repairs muscle tissue and returns to its resting state. High-intensity workouts like high-intensity interval training (HIIT), sprint intervals and resistance training create the largest afterburn effect because they require more post-workout recovery energy.

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Key takeaways

• The afterburn effect is also called EPOC.
• HIIT and strength training create the largest afterburn effect.
• The effect can last from several hours up to 24 to 48 hours depending on workout intensity.
• Most studies show EPOC burns an additional 6 percent to 15 percent calories beyond the workout itself.
• Intensity matters more than workout duration.

The key to increasing the afterburn effects of your workouts, so you can burn more calories throughout the whole day, is practicing high-intensity exercises. That’s because the afterburn effect is small following steady-state traditional cardio workouts like jogging but is significantly higher following intense workouts, like sprinting, circuit, strength and burst activities.

If your goals are to get leaner, build muscle fast, increase your cardiovascular health and not spend loads of time needing to exercise, then the bottom line is that doing brief, but intense, intermittent bouts of exercise is the way to go. The benefits of high-intensity interval training are greater strength, improved speed and better fat burning, all in ways that steady-state cardio workouts simply can’t comparably create.

In general, the more intense the exercise, the greater the afterburn effect is going to be. This means that a workout that’s 20 minutes long involving sprinting (or practicing another form of burst training or intense activity) as fast as you can for 30 seconds, repeated for 10 rounds with 90-second rest periods in between, will have a higher afterburn effect compared to doing steady-state exercises like running moderately for 30 minutes.

How many more calories will the afterburn effect burn through following intense exercise? It’s hard to estimate an exact amount since every person reacts to high-intensity exercise differently. Factors like someone’s current level of fitness, gender, age, training duration and intensity can potentially influence the magnitude of the afterburn.

That being said, one study published in the Journal of Exercise Science showed that the afterburn effect is associated with an elevation in metabolism due to the thermic effect of activity regardless of your current fitness level, and some experts believe that this can cause around a 10 percent increase in calorie expenditure for the day following just 20 minutes of high-intensity exercise.

In other words, if you’re an active woman who normally burns 2,000 calories a day, taking into account your additional energy requirements might mean you’re now burning 2,200!

Here’s the scientific breakdown of the afterburn effect:

HIIT workouts increase your metabolism. In other words, they raise your total energy expenditure, which is the amount of calories your body burns for energy daily.

You can think of energy expenditure as the amount of energy a person uses up throughout the entire day performing all bodily activities, whether it’s walking around, showering or bending over. We all use up energy in the form of calories every time we breathe, move, digest food and our heart pumps out blood, so most of our energy expenditure goes without us even noticing or making an effort.

When it comes to exercise, of course, we do take notice of our increased effort and, therefore, the higher amount of energy we’re using. But the energy expenditure of a workout is the total measure of calories burned during and after exercise, so while we might be pushing ourselves at the gym and “feeling the burn,” we actually continue to use extra energy once the workout is over without even realizing it.

As you’re learning, certain forms of exercise (high-intensity) dial up the energy burn following exercise better than others. After intense exercise, your body has to work twice as hard to replenish its oxygen stores than it does after steady-state exercise.

The technical name for calories burned after exercise is “excess post-exercise oxygen consumption,” or EPOC. Evidence suggests an exponential relationship between exercise intensity and the magnitude of the EPOC.

The term EPOC describes the fact that at higher exercise intensities, oxygen uptake isn’t proportional to heat expenditure. In other words, EPOC results in an oxygen debt because this is how the body works to recover after a tough workout and brings the organs, heart and hormones back to a resting state.

The oxygen debt component is part of the reason there’s an afterburn effect because it takes a toll on energy use. In fact, this process of bringing the body back to homeostasis and normalizing metabolism following intense activity might take up to three days!

The more often you do intense workouts, the more it pays off. The International Journal of Sports Nutrition and Exercise Metabolism reports that EPOC varies as a function of metabolic stress, and more training improves the efficiency of metabolic regulation during recovery from exercise.

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EPOC is not the only thing that accounts for the afterburn effect. Other aspects have to do with the body’s production of lactic acid and the process of hypertrophy, or the building of muscle mass.

Think of it this way: If you’re wearing your muscles out and producing higher levels of lactic acid (the chemical reaction that is responsible for the “burn” you feel when your muscles are fatigued), then you’re causing damage to muscle tissue at the microscopic level that needs to be repaired. This takes energy because it involves the body breaking down amino acids (proteins) in muscles and then rebuilding them.

In the process, intense exercise also increases testosterone naturally, which can mean more muscle gain.

This process of laying down new proteins in order to build back muscles stronger and bigger raises your total energy expenditure, and basically all of this happens after you finish working out.

How many extra calories does the afterburn effect burn?

Most research suggests the afterburn effect burns approximately 6 percent to 15 percent additional calories on top of the calories burned during exercise, although results vary based on workout intensity, fitness level and muscle mass.

For example:

• A workout that burns 400 calories may burn an additional 24 to 60 calories afterward.
• Intense interval training and heavy resistance training create larger EPOC responses than steady-state cardio.
• Higher-intensity workouts generally create exponentially greater afterburn effects than moderate exercise.

While the afterburn effect is real, it should be viewed as a bonus benefit rather than a magic fat-loss solution. Consistent exercise, muscle building and nutrition still matter most for long-term body composition changes.

How long does the afterburn effect last?

Depending on workout intensity, the afterburn effect may last anywhere from a few hours to as long as 24 to 48 hours after exercise. However, the majority of additional calorie burn usually occurs within the first several hours post-workout.

Factors that influence duration include:

• exercise intensity
• workout volume
• muscle mass involved
• training experience
• recovery needs

HIIT, sprint intervals and heavy compound strength training tend to create the longest-lasting EPOC responses.

Best workouts for the afterburn effect

1. HIIT workouts

High-intensity interval training consistently produces one of the strongest afterburn effects because it alternates intense bursts of exercise with short recovery periods.

Examples:

• sprint intervals
• assault bike intervals
• rowing intervals
• Tabata workouts

2. Strength training

Heavy resistance training increases EPOC because muscle repair and recovery require substantial energy after exercise. Compound lifts tend to create the largest effect.

Best exercises:

• squats
• deadlifts
• lunges
• push presses
• pull-ups

3. Circuit training

Circuit-style workouts combine strength and cardio stress while minimizing rest periods, which can significantly increase post-workout calorie burn.

4. Sprint training

Short sprint sessions create large metabolic disturbances that increase oxygen consumption after exercise.

How to activate the afterburn effect

For years, we’ve been led to believe that exercising for longer periods of time results in more calories burned and, therefore, a better body composition. In recent years, the idea that you can reach your goals by following an exercise regimen that’s actually the opposite is now well-supported by a growing field of research.

A 2011 report published in the Journal of Obesity states that although generally the effects of regular aerobic exercise on body fat is negligible, intense forms of exercise may have a greater impact on body composition. “Emerging research examining high-intensity intermittent exercise (HIIE) indicates that it may be more effective at reducing subcutaneous and abdominal body fat than other types of exercise.”

During aerobic exercise, the muscles use glucose (sugar) primarily for energy. On the other hand, during the longer recovery period described above, the body primarily uses fatty acids in addition to glucose. This translates into you burning more fat while you build more muscle.

That’s important because, even at rest, muscle burns more calories than stored body fat does.

How much intense exercise do you need to do? This depends on how intense your workouts are.

For example, the World Health Organization has switched away from simply recommending steady-state exercise and now advises the following:

Here are three ways to practice high-intensity exercise in order to dial up your afterburn effect:

1. Cycling, using the elliptical or rowing

Instead of doing steady-state cardio for 50 minutes, halve this amount, and use interval training.

High-intensity interval training combines short, high-intensity bursts of exercise with slow, recovery phases. These intervals are repeated throughout one short (15- to 20-minute) session.

The intense parts are done at 85 percent to 100 percent maximum heart rate, rather than 50 percent to 70 percent that is the average moderate endurance activity level.

A simple way to practice HIIT is to push yourself as hard as you can for about 20 to 30 seconds, then take a rest of about 60 seconds. Repeat this cycle for the duration of your exercise.

The shorter your rest interval is, the harder it will be. You should feel wiped out afterward!

2. Weight lifting or resistance training

Practice a circuit-style workout or complete “supersets.” Supersets are when you go from one weighted exercise straight into the next, without resting in between. You work one muscle group hard until it’s fatigued, then move on to another one right afterward.

In other words, you use opposite muscle groups so while you rest one, you train the other. For example, you might start with squats working your legs primarily, then move on to bench presses working your upper body primarily. Or you go from back rows to chest presses.

Also, to radically switch up your routine, give HIIT a try by incorporating some full-body kettlebell workouts, or do CrossFit workouts.

3. Sprinting

This is likely the most popular way to practice HIIT and achieve high afterburn effects. This model follows the same idea as that for cycling or rowing mentioned above; you swap a longer steady workout for a shorter but intense one.

And I mean intense!

During your sprints, you really want to push yourself, almost like you’re running because your life depends on it. Try sprinting for 10 to 15 minutes total to start, using 90-second intervals. This means pushing yourself very hard for 30 seconds, then taking a rest for one minute.

Repeat the cycle until you’re at about 15 minutes or slightly more once you’ve been practicing HIIT for a while. You can practice this outdoors or take it inside for an intense burst-training workout on a treadmill.

What exercises produce the smallest afterburn effect?

Low-intensity steady-state cardio, such as casual walking, light cycling or easy jogging, generally produces a much smaller afterburn effect than high-intensity training.

That does not mean low-intensity exercise is ineffective. It can still support:

• cardiovascular health
• recovery
• calorie expenditure
• stress reduction

However, it typically creates less excess post-exercise oxygen consumption compared to intense interval or resistance training.

Common myths about the afterburn effect

Myth No. 1: The afterburn effect melts fat for days

While EPOC can remain elevated for up to 24 to 48 hours, most extra calorie burn happens relatively soon after exercise.

Myth No. 2: Long cardio workouts create the biggest afterburn

Workout intensity generally matters more than duration when it comes to EPOC.

Myth No. 3: The afterburn effect replaces proper nutrition

The afterburn effect can support fat loss, but nutrition and overall calorie balance remain the most important factors for body composition.

Myth No. 4: Only athletes can benefit from EPOC

Even beginners can improve post-workout calorie burn by gradually incorporating interval training and resistance exercise.

Precautions

There’s still a lot to learn about the afterburn effect and how exactly it works. Almost every aspect of a workout, from the number of reps and sets completed, number of rest periods in between sets, intensity, speed, types of movements performed, and a person’s heart rate, can all impact how dramatic the afterburn effect turns out to be.

It appears that well-trained individuals have a more rapid return of post-exercise metabolism to resting levels after exercising. Therefore, they might be getting the most bang for their buck when it comes to HIIT workouts.

Nonetheless, there are plenty of benefits for people new to exercise, too, assuming they start slow and prevent injuries. One of the biggest challenges might be encouraging HIIT newbies and those who have weight to lose to even start intense exercise programs that can raise their afterburn effect, since intensity can be intimidating.

If you’re practicing HIIT for the first time, keep your workouts shorter, around 10 minutes, and use a method that you’re comfortable with, like running (on grass or a treadmill) or cycling.

Regardless of how fit you already are, HIIT workouts shouldn’t be done every day because this can increase injury risk. They’re best when completed just two to three times a week (or even less in some cases).

If you choose to do a circuit-style intense workout or one using weights, consider starting with a professional trainer to make sure your form is correct and you aren’t setting yourself up for injury.

Frequently asked questions

Is the afterburn effect real?

Yes. The afterburn effect, or EPOC, is well documented in exercise science and refers to increased oxygen and calorie consumption after intense exercise.

What workout has the biggest afterburn effect?

HIIT workouts, sprint intervals and heavy resistance training generally produce the highest EPOC response.

Is the afterburn effect good for weight loss?

The afterburn effect may modestly increase total calorie expenditure and support fat loss efforts, especially when combined with strength training and proper nutrition.

Does walking create an afterburn effect?

Walking produces only a small EPOC response because it is low intensity compared to interval or resistance training.

What is another name for the afterburn effect?

The scientific term for the afterburn effect is excess post-exercise oxygen consumption (EPOC).

Conclusion

• The afterburn effect (EPOC) is the increased calorie burn that occurs after intense exercise while your body recovers and restores oxygen levels.
• HIIT, sprint intervals and resistance training create the largest afterburn response, although the total additional calorie burn is generally modest.
• Consistency, workout intensity and muscle-building exercise are the biggest factors in maximizing results.