HIIT is often touted for the massive calorie burn it creates after each workout, known as “The Afterburn Effect.”
However, I call bulls**t.
Okay, maybe that was a little extreme…
But today I want to show you that this burn certainly isn’t as great as you’ve been led to believe…
See, regular cardio has been kicked to the curb in recent years in favor of high intensity interval training and, sure, HIIT certainly has a lot of performance benefits which I love.
But in becoming popular, the fitness industry has gone f**king crazy…
Suddenly, regular cardio is “bad for you”, and there’s “no point in doing it”. This all or nothing approach is utter nonsense.
A client of mine recently told a pal that she burned over 1300 calories in a single day through a combination of weight training, teaching a class, and achieving over 10,000 steps with a nice seaside walk.
That’s a great achievement.
But her pal dismissed it, claiming that the 15 minute fitness class she attended had her burning even more.
She couldn’t track it to give a number, of course, because those calories were burned after the workout ended through “The Afterburn Effect.”
So today I’m going to be giving you some straight up facts about HIIT, and we’ll also reveal if her pal really did create that amazing calorie burn in as little as fifteen minutes.
Spoiler: No she f**king didn’t.
The Afterburn Effect
There are two areas of misinformation which are popular within the fitness industry when talking about “the afterburn effect” from HIIT.
The first is the duration (i.e. how long the afterburn effect lasts after each workout).
The second is the amount of calories burned.
So let’s start with that first one…
If you take a look at the cover of most home workout DVD’s, you’ll see trainers trying to out-crazy each other with their bizarre claims of “burning calories on auto-pilot for 36 hours!”
It doesn’t matter that you only did a five minute circuit during the commercial break of a TV show… you will now burn more calories than Rocky Balboa going f**king nuts in a Russian barn.
In a bid to outdo the last one, they will up the ante with every sales pitch:
… “You will become a fat incinerating machine for up to 36 hours after our workouts!”
… “Our fitness class will boost your afterburn effect 5x more than any other fitness class!”
… “For every 500 calories you burn in the gym with us, you’ll go on to burn an exra 500 more thanks to the afterburn effect!”
But the length of the afterburn effect is nowhere near that which is often advertised.
A study published in Medicine and Science in Sports and Exercise back in 2011 confirmed that the afterburn effect can only last up to 14 hours. (1)
So we should take sales graphics like this and throw then in the sea:
30 hours of fat loss, and it comes with a significantly greater calorie burn the entire time versus steady state cardio?
According to this, you could be performing cardio for all 30 hours and never achieve the same level of calorie burn as your friend who went home 29.5 hours ago.
The holy grail of fat loss!
If the afterburn effect caused by HIIT was this effective, I could essentially perform three quick workouts then sit on the couch for the rest of the week.
You, sir, have unlocked the secret to helping the nation lose weight by doing barely any exercise and not even f**king mentioning changing their diet…
Take my money!
Nope… wait… because this one goes even further:
In a bid to outdo every other fitness class in the area, this one claims their HIIT workout will make you burn more calories for a whopping 48 hours!
Take that, previous infographic which was impressive until we saw this one!
Of course, both are total bulls**t.
In reality, it should look a lot more like this:
How Many Calories Does The Afterburn Effect Burn?
So now we know it lasts for up to 14 hours, let’s take a look at the second area of misinformation:
How many calories does the afterburn effect really burn?
“For every 500 calories you burn with us in the gym, you’ll burn an extra 500 calories after the workout!”
That’s a 100% rate of E.P.O.C. (excess post-exercise oxygen consumption – the “science name” for the afterburn effect).
That figure is unheard of in any scientific review of HIIT. Ever.
Quite frankly, if you burned the calories some trainers are suggesting, you’d be f**king dead in a week!
Claims like this are typically used as a marketing tactic because it’s generally impossible for a consumer to know if it’s true or not. So when one class claims you’ll burn 25% more calories after your workout ends, another claims their workout will burn 35%, then another claims 50%, and so on…
It’s like a woman polling 200 guys on the size of their d**k – she’ll get some very impressive answers.
So here’s the truth.
Review studies on HIIT have shown the afterburn effect to fall somewhere between a typical 6% and a maximum of 15%. (2)
Yes. That’s it.
If you’re a long-term reader of my work, you’ll previously have heard me state that “the best diet is the one you can stick to”.
Well, the same could be said of your exercise program.
Meaning you don’t need to force yourself to do something you hate, just because somebody claims it’s vastly superior.
That’s why there’s so many different training programs and protocols to use inside my workout app – no two people will like the exact same things.
HIIT is great, and I love doing it for the athletic benefits it offers, but if you are performing HIIT purely for fat loss purposes and hating every second, you’d likely produce greater long-term results through building something more sustainable.
I’ll explain below.
To drive that point home, let’s take a look at some more research regarding cardio for fat loss.
A fantastic meta-analysis published in 2017 looked at the available body of research comparing the effects of high intensity interval training versus aerobic cardio.
The researchers found no difference in fat loss or energy expenditure between HIIT and steady state cardio. (3)
That’s right; no difference!
So you do the one that fits your life the best. The most important aspect (by far) is that you do something.
And I know there’ll be folks out there reading this asking, “But what about the afterburn effect from the HIIT workouts?”
Surely if we take that into consideration, the HIIT workouts would inevitably lead to more fat loss and a higher calorie burn, right?
Well, not really.
A 1997 study from a team at the University of South Australia found that a group of trainees who performed a 30 minute low intensity cardio session had an E.P.O.C. of around 32 calories, whereas a group of trainees performing 20 x 1 minute intervals at 105% VO2 Max (f**king flat out) had an E.P.O.C. of 64 calories. (2)
The researchers also state that:
“The optimism shown in earlier research regarding the importance of E.P.O.C. in weight loss is generally unfounded.
This is further reinforced by acknowledging that the exercise stimuli required to produce prolonged E.P.O.C. is unlikely to be tolerated by non-athletic individuals.”– J. LaForgia
Once again, this shows that we should not be training purely for “the afterburn effect” – because it is not all it’s cracked up to be.
If you burn more calories via HIIT it’s because you’re working like a motherf**ker during your actual workout, and not because of what happens after the session, as was previously thought.
Those extra 32 calories don’t even add up to a couple of rice cakes, so we have to consider whether an untrained individual needs to be driving themselves into the f**king ground for the sake of achieving them, as it will likely lead to an unsustainable workout program and, therefore, unsuccessful long-term adaptations being made.
Steady state cardio definitely still has a place in the fitness world.
So there you have it!
The afterburn effect isn’t the holy grail of fat loss it was once believed to be, and if you are restricted from performing high intensity interval training you needn’t worry that you’re losing out on some magical fat loss formula.
Consistency is still the most important factor in weight loss.
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- Knab, A. M., et al. A 45-minute vigorous exercise bout increases metabolic rate for 14 hours. Med Sci Sports Exerc. (2011)
- LaForgia, J., et al. Effects of exercise intensity and duration on the excess post-exercise oxygen consumption. J Sports Sci. (2006)
- Keating, S. E., et al. A systematic review and meta-analysis of interval training versus moderate-intensity continuous training on body adiposity. Obes Rev. (2017)