Updated: Jun 2, 2020
EPOC_ The True “Secret” for Weight Loss
By Coach Sam 4/29/20
“Rapid” and “effortless” weight loss are the proverbial holy grail sought by those looking to overhaul their physiques in a short matter of time. But, truth be told, there is no shortcut to losing weight, burning fat, or achieving the body of your dream. You didn’t get out of shape overnight, and you can’t expect to obtain the physique of a Greek god or goddess overnight (or even over one month), either. Hard work, dedication, and consistency are non-negotiable to maximizing your results. But...there are a few tweaks you can make to your training that can accelerate how quickly you achieve your desired outcomes. Once such “tweak” is known as after-burn training. What is “After-burn Training”? The “after-burn effect”, technically known as Excess Post-Exercise Oxygen Consumption(EPOC), has been all the rage in recent years, particularly amongst group fitness classes, crossfit boxes, and home workout programs. The “after-burn” refers to the extra calories your body burns following an intense workout. As you have likely experienced for yourself, high intensity workouts (heavy resistance training, HIIT, etc.) place a greater demand on the body’s resources (oxygen, ATP, etc.) and create tremendous homeostatic disruptions. In order to bring the body back to a state of equilibrium (homeostasis), it consumes more oxygen and burns more energy to restore balance. Included in the tasks your body has to do to restore equilibrium following a high-intensity workout are: Regeneration of ATP stores
Replenishment of oxygen stores
Refueling of creatine stores
Removal of lactic acid
As mentioned previously, to carry out these processes, the body has to consume extra oxygen (and energy), which results in a greater number of calories burned above the resting metabolic rate (RMR). Essentially, the “after-burn effect” refers to a metabolic state in which the body continues to burn a higher number of calories compared to what it normally would at rest following intense exercise. How “Significant” is EPOC? Depending on whose marketing and advertisements you’ve seen, you’ll encounter some pretty outlandish claims regarding just how significant, or meaningful, the effects of EPOC are. Research indicates that the after-burn effects lasts between 10-72 hours post workout, with the greatest spike in oxygen consumed (and thus, calories burned) within the first hour after training. Most studies to date show that the “after-burn effect” will burn an extra 5 calories for every extra liter of oxygen consumed. However, the magnitude and duration of the after-burn effect hinges on several factors, including:
Type of exercise (cardio or weightlifting)
How long you work out (duration)
Interestingly, some other studies indicate that resistance training at either a low or high intensity produce similar post-exercise oxygen consumption, provided total work volumes are equated. In total, the after-burn effect may help you burn an additional 76-150 calories while at rest compared to what you would burn if you hadn’t crushed an intense EPOC-surging workout.[1,5] As you can see, it’s not much, but when you’re trying to lose fat as quickly as possible and make the most of your transformation challenge, every little bit helps! EPOC and Cardio The two main factors that affect EPOC are the intensity and duration of exercise. As intensity and/or duration increase, so too does the magnitude and duration of EPOC. To showcase this, a study compared individuals cycling at intensities of 29%, 50%, and 75% of their respective VO2 max for 80 minutes. At the end of the study, the team of researchers noted that the greatest afterburn effect was observed in the group cycling at 75% of the VO2Max. Their average EPOC lasted for ~10.5 hours and burned an additional 150 calories. 150 calories is a meaningful amount of calories for some individuals, but the issue is that you’re doing 80 minutes of moderate-intensity, steady-state cardio at 75% of your VO2 Max to create this effect. If your goal is to build or maintain muscle, you don’t want to be wasting that much time on cardio each day. You want to keep cardio to a minimum, but make it impactful. This brings us to the topic of high-intensity interval training (HIIT). HIIT creates a higher after-burn effect compared to moderate-intensity cardio, but it’s not that big of a discrepancy. For example, a 1997 study compared two different exercise groups. The first group did a “steady state” cardio workout where they ran continuously at 70% VO2 max. The second group completed 1-minute sprint intervals, pushing their VO2 Max to 105%. They then rested 2 minutes and sprinted again. At the end of the study, researchers noted that the sprinting group had an EPOC of ~69 calories and the steady state group had an after-burn effect of about half. As you can see, the after-burn effect isn’t that big on a day to day basis, but over weeks and weeks of training it can add up. Additionally, performing too much steady-state, moderate intensity cardio can actually impair recovery and muscle growth. HIIT can be performed several times per week without eating into lean muscle or causing excessive breakdown. Either way, the takeaway here is that the after-burn effect or cardio isn’t as large as it’s been made to be, but when combined with other effective fat loss strategies (proper diet, resistance training, etc.), it can accelerate your results. Speaking of resistance training…
EPOC and Resistance Training As mentioned above, the afterburn effect hinges on the intensity and duration of your workout. This holds true for EPOC and resistance training, too. Studies note that the EPOC of resistance training can last between 15-38 hours and creates a boost in metabolism between 9-11%. To put this in perspective, if your basal metabolic rate (BMR) is 1500 calories, you might burn an extra 150 calories during your recovery period. Unfortunately, to obtain these results, the studies had subjects doing workouts that consisted of 30 and 60 working sets per training session. That kind of training volume just isn’t sustainable or practical for the average individual. Still, there is some research noting that more reasonable training programs can create a significant after-burn effect -- provided the intensity is sufficient. “Intensity” in this case refers to how close to your 1-RM you’re lifting. For example, one study documented that 60 minutes of resistance training with 85% of 1RM increased metabolism over the following three days. This resulted in subjects burning several hundred more calories than individuals who trained at lower intensities (45-65% of 1RM). The takeaway here is that heavy resistance training elicits a greater after-burn effect than cardio. And, it also does a better job of building and retaining muscle than cardio. But, EPOC shouldn’t be the sole focus of your fat loss plan. It is but one component. You still need to consider the energy burned during the actual workouts as well as how many calories you’re cutting from your diet to create an energy deficit. This is why the fastest way to lose weight is by using a combination of diet, cardio, and resistance training. Combining heavy resistance training with a handful (3-4) HIIT cardio session per week may help you burn up to an extra 1,000 calories each week thanks to the after-burn effect.
The Bottom Line on EPOC and Weight Loss EPOC and the “after-burn” are gigantic buzz words in the fitness and weight loss industry. But, their effects are only one component of a successful weight loss approach. You also need to factor in the calories you burn during training as well as those expended during non-exercise activity (walking to the mailbox, folding laundry, fidgeting, etc.). All of this movement adds up. If you’re looking to maximize EPOC (without impeding recovery or losing lean muscle), your best bet is to hit your workouts hard and heavy, but keep them brief. This maximizes the after-burn without affecting your lean muscle. References:
Bersheim, E. and Bahr, R. (2003). Effect of exercise intensity, duration and mode on post-exercise oxygen consumption. Sports Medicine, 33, 14, 1037-1060
LaForgia J, Withers RT, Gore CJ. Effects of exercise intensity and duration on the excess post-exercise oxygen consumption. J Sports Sci. 2006;24(12):1247–1264. doi:10.1080/02640410600552064
Woodard, Tyler J., "Comparison of Timed-Based Sets Metabolic Resistance Training vs. Repetition-Based Sets Metabolic Resistance Training on EPOC in Recreationally Active Young Women" (2014). Research Papers. Paper 538.
Thornton MK, Rossi SJ, McMillan JL. Comparison of two different resistance training intensities on excess post-exercise oxygen consumption in African American women who are overweight. J Strength Cond Res. 2011;25(2):489–496. Doi
Quinn TJ, Vroman NB, Kertzer R (1994). Postexercise oxygen consumption in trained females: Effect of exercise duration. Med Sci Spots Exer 26: 908-913.
Bahr R, Sejersted OM. Effect of intensity of exercise on excess postexercise O2 consumption. Metabolism. 1991;40(8):836–841. doi:10.1016/0026-0495(91)90012-l
Laforgia J, Withers RT, Shipp NJ, Gore CJ. Comparison of energy expenditure elevations after submaximal and supramaximal running. J Appl Physiol (1985). 1997;82(2):661–666. doi:10.1152/jappl.19184.108.40.2061
Scott C. Misconceptions about Aerobic and Anaerobic Energy Expenditure. J Int Soc Sports Nutr. 2005;2(2):32–37. Published 2005 Dec 9. doi:10.1186/1550-2783-2-2-32
Fatouros IG, Chatzinikolaou A, Tournis S, et al. Intensity of resistance exercise determines adipokine and resting energy expenditure responses in overweight elderly individuals. Diabetes Care. 2009;32(12):2161–2167. doi:10.2337/dc08-1994