EPOC & Afterburn – Are They Real or Is It HYPE?
October 5, 2009 | 6 Comments
I talk a lot about EPOC, Afterburn, and the idea of burning calories and fat even after your workout is over. Over the past couple blog posts there have been some questions from readers about this concept. Is is real? Is it over hyped? How many calories are we talking about? Here is a question/comment from a reader, Jack , about this very thing:
You wrote that “Metabolic Circuits are essential to really crank up your weight loss because they have been shown in research studies to increase the total number of calories that you burn over the 38 hours following your workout.” Is this the same as when people speak of EPOC or a separate phenomenon? I ask this because I have read that EPOC is about 8-15 percent or so (depending upon activity intensity) of the total kcal expenditure during the chosen activity. As such quite a number of writers claim that any metabolic boost is not nearly as significant as it is made out to be. Not being engrossed in all of the research leaves me slightly confused as to which is closer to the reality of the situation.
Just curious if you can add some more clarity. I do not mean to come across as argumentative, I am just somewhat confused by what seems to be a back and forth between claims about significant metabolic boosts for 1+ days after certain types of activity and other claims that such impacts are largely overblown.
This is a great question. Yes, I was talking about EPOC or what Alwyn Cosgrove calls Afterburn.
What is EPOC/Afterburn? It is basically a phenomenon that occurs when you lift weights or do the metabolic type of training that I have been talking about the past couple of blog posts. The tabata protocol is a perfect example of something that elicits an afterburn effect. A very simple way of thinking about EPOC is that when you do this type of training you exert yourself beyond what your body is capable of handling (i.e. your body can’t keep up); it then uses the next 12, 24, or even 36 hours to ‘catch up’ metabolically. ‘Catch up’ = burning calories.
How many calories do you burn with EPOC? A bunch.
What is the reality of the situation? Is is 8%? 15% as Jack noted about?
I was emailing back and forth with Alwyn Cosgrove about this and here is what he had to say…
The “reality of the situation” is not going to be found in textbooks or papers unfortunately.
Basically it’s hard to truly measure caloric expenditure (during and post workout) of anaerobic activity and recovery when you are using a measure of aerobic work (traditionally oxygen debt).
Studies comparing the same volume of caloric work (ie same calories burned) from interval training or weight training to aerobic training, show a massive difference in total fat lost over a period of time?
Why? EPOC? Some other type of post workout change?
I don’t think we know the exact mechanism yet – we just know that SOMETHING happens post workout as a result of high intensity metabolic work that doesn’t happen with lower intensity work, even if calories burned during training are equal.
The numbers shown with EPOC don’t explain it completely. It would be nice to know exactly what happens, but more importantly we KNOW what happens — more fat loss.
Bottom Line - don’t be confused by “a back and forth between claims” – just do what has been shown over and over again to work.
Aside from all of this: – all the studies on EPOC are performed on aerobic work or standard weight training.
- The few studies on circuit based weight training show a higher effect.
- There has never been a formal study on the type of training we use. However – at 250 clients training 3 times a week for the past several years – I think I have more than enough “data”
- There aren’t any studies on an accumulative effect on EPOC (they all look at single workouts). If it’s even a 10% increase for 24 hours, is there an accumulative effect if you train every 24 hours? (there are studies showing an increased EPOC with two shorter daily sessions as opposed to one of the same total length) — the question is how long will the “between sessions” last?
We know that weight training increases resting energy expenditure and there is an EPOC effect. All we do is attempt to continuously ramp that effect up.
Again – in truth we don’t know the mechanisms behind this completely — I just know what results my clients get.
The research doesn’t disprove the results. It just looks at the mechanisms to explain the results.
(Mike again…) We talk a lot about EPOC in Warp Speed Fat Loss. As Alwyn said is all the extra calorie burning from EPOC? Not sure? Does is matter if we know exactly what it is from? Not entirely, as if you go on Warp Speed Fat Loss and lose 4 pounds a week for 4 weeks would you really care if it was EPOC or not? You’d just be happy you lost the weight right? So for now the jury is out but as soon as we learn more I’ll let you know. For the time being let’s just do what we know works —> This works 
Please post your comments/thoughts below.
6 Responses to “EPOC & Afterburn – Are They Real or Is It HYPE?”
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Mike,
Thank you for the follow-up. It is much appreciated. The more I can get other people challenging my current thoughts, the better, and you're one of the best.
Mike, I learned of this about a year and a half ago. I tried it and can't explain it either but it does work. I wear a heart rate monitor when I work out. A Polar F6. I've tried a 60 minute steady state cardio workout on a treadmill. The treadmill at 3.5-4.0 MPH at a 15 degree incline for 60 minutes and a 5 minute cool down…I burn around 900 calories. Then, on the elliptical…level 17 out of 25. I set it for 19 minutes. I do a 5 minute warmup. Then for 14 minutes I do a 30 second all out sprint followed by a 60 second recovery. That's 10 30 second sprints and 9 60 second recoveries for 14 minutes. It ends with a 3 minutes cool down. That's 22 minutes and I burn 375 calories. That's less than half the time but I am wasted afterwards and I feel like I really worked very hard compared to the steady state. I've found that shorter more intense workouts are much more productive and I spend less time in the gym.Anyway, this "afterburn" really does work… for me anyways.
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Hi Mike.
I suppose the "real" question is whether or not metabolic training, worrying about EPOC or other mechanisms, or comparing potential speed of results is even necessary once you have a trainee making excellent nutritional choices suited to his goals at least 80-90 percent of the time, lifting weights a handful of times per week focusing mostly on "big bang" movements with appropriate intensity(regardless of session structure, specific frequency, or even volume), and doing some form of energy systems work 2 or 3 times a week (even if it is on the low intensity end of the scale). If a person weren't fairly lean and muscular from that, I'd imagine that something was wrong or the person wasn't doing all of the things listed.
Taken another way, we could break down most goals to (1) athletes seeking performance in a chosen sport, (2) physique competitors, (3) general population- muscular gain, (4) general population- fat loss, and (5) general population- physique maintenance with strength gain/general health.
Group 1 will have training structure dictated by available time and demands of the chosen sport.
Group 2 will do whatever it takes to get ultra lean while retaining maximum muscle mass……………and this often means using low intensity ESW over high-intensity varieties and eventually cutting back on or even cutting out metabolic resistance training sessions. While there are technically time constraints, the primary goal is maximum leanness and muscularity, regardless of whether or not you need to start prepping a few weeks earlier than you might otherwise want to.
As far as groups 3, 4, and 5 are concerned, only group 4 would need to have a more dialed-in focus on methods that may be most conducive to fat loss. And even then, depending upon how close that group was to the main goal and based upon things like life stressors and such, metabolic training sessions may not be used to any significant degree or even be 100-percent appropriate. I know that they can be widely effective and that in AC's hierarchy based upon available time they are higher up on the list, but it still seems like solid "heavy" resistance training, impeccable nutrition habits, and even some low to moderate intensity conditioning work would get a person close to physique goals in a very timely fashion so long as compliance is on the high end of the scale.
And since nutrition (something near and dear to your heart) is usually regarded as the most critical component for attaining the desired body composition, it seems like debating metabolic resistance training versus low intensity work versus HIIT, or what ever else people want to throw into the mix is (without sounding too callous or smug) almost pointless. Heavy training to retain/build muscle, optimized nutrition to support maintenance, growth, and manage body composition, and then whatever type of energy systems work fits your schedule, personality/preference, and biomechanical/postural considerations/needs.
Sorry for the rathe lengthy and somewhat desultory post!
I was at a plateau when I ordered the Warp Speed Fat Loss, however, due to training for a powerlifting competition, could not follow the whole program. I did however utilize the interval cardio tips to ramp up my program and have been steadily decreasing fat ever since. I have to agree, the why is less important for me than the results!
Yes.
Thanks,
Mike