What is EPOC and How it Accelerates Fat Burning

Patrick DaleTraining1 Comment

EPOC sounds like it should be some kind of backed-by-science sports supplement or maybe a secret government law enforcement agency but, in reality, it’s one of the keys to fast and efficient fat loss.

To lose fat, you need to create a calorific deficit which basically means you have to eat less, exercise more or do a little of both. EPOC is like a multiplier that helps create an even greater calorific deficit by elevating your metabolism.

What is EPOC?

EPOC is short for Excess Post-exercise Oxygen Consumption and was once commonly referred to as oxygen debt. It has also been referred to as the afterburner effect for reason that will soon become obvious.

Exercise falls into two broad categories; aerobic and anaerobic activities. Aerobic activities include jogging, swimming and walking and are performed at a slow to moderate pace during which fat is the primary source of fuel. Anaerobic exercise is much faster paced and carbohydrates in the form of glucose and glycogen are the main source of fuel.

On initial consideration, this would suggest that aerobic exercise is best for fat loss but, in truth, this is not really the case.

While it is true that fat is your primary source of energy during aerobic activities, because fat is so energy dense, very little of it is used during aerobic activity and while your metabolic rate (the number of calories you are burning) increases while you are exercising, it soon returns to normal once your workout is completed.

In contrast, anaerobic activities such as interval training or resistance training burn more carbs than they do fat but increase your metabolic rate much more and also keep it elevated for hours after your workout has finished; that’s the EPOC or afterburner effect.

Drivers, start your engines!

Think about it like this; if you drive your car at a steady 50-mph for an hour, you will not use much fuel and, once your journey is complete, your car’s lightly-used engine will soon cool down.

In contrast, if you make the same journey with your accelerator pressed hard to the floor, your journey will take less time but will also less economical and the engine will take far longer to cool down once you reach your destination. This is the very essence of EPOC.

Triggering EPOC


Medicine ball slams; a great EPOC triggering exercise Source: Patrick Dale

Intense workouts such as interval training, resistance training, circuit training and many of the metabolically demanding CrossFit workouts create a lot of oxygen debt which simply means they push you out of your aerobic training zone and into your anaerobic training zone. This results in a massive increase of lactic acid production – the stuff that makes your muscles burn – and the more lactic acid is produced, the greater the EPOC effect.

The greater the build-up of lactic acid, the longer the EPOC effect will be because EPOC is essentially your body’s way of clearing up that accumulation lactic acid.

Research suggests that the EPOC effect can last around 24-hours after exercise which means that, as well as burning more calories while you exercise, your calorific expenditure will remain elevated until well into the following day. Remember; the higher your metabolic rate, the more calories you burn and, assuming you do not eat more than normal, the greater your calorific deficit will be. The greater the calorific deficit, the faster you’ll lose fat.

Get your EPOC on!

Triggering EPOC means getting out of your comfort zone. For example, running 400-meter repeats on the track, 500-meter repeats on the rower or three-minute sparring rounds in the boxing ring or on the wrestling mat. Many CrossFit workouts are also ideal for triggering EPOC including…


For time:




Fight Gone Bad

Three rounds of…

60-seconds wall-ball, 20 pound ball, 10 ft target (Reps)

60-seconds sumo deadlift high-pull, 75 pounds (Reps)

60-seconds box Jump, 20″ box (Reps)

60-seconds push-press, 75 pounds (Reps)

60-seconds row (Calories)


7 rounds for time of:

11 body-weight deadlifts

100-meter sprint

Safety first

The key to triggering EPOC (and therefore maximizing your metabolism and fat loss) is pushing yourself into your discomfort zone and that means working against the clock and trying to either perform your workouts in as short a time as possible or doing more work than usual in the same amount of time. This generally means moving more and resting less. However, you’ll need to be reasonably fit before trying these kinds of workouts.

In addition, it’s important not to sacrifice good exercise form for speed as performing exercises incorrectly can lead to injury.

If you are new to EPOC-triggering CrossFit workouts, make sure you ease yourself in gradually and develop a decent base level of aerobic fitness before you try to take on the likes of Fran or Sham.

Many CrossFit workouts are very intense and will trigger a high level of EPOC which makes them ideal for promoting rapid and efficient fat loss. While you can lose fat by doing steady paced jogging and other aerobic activities, if you want to lose fat as fast as possible, EPOC will really get the job done.

The following two tabs change content below.
Patrick Dale is an ex-British Royal Marine, gym owner, and fitness qualifications tutor and assessor. In addition, Patrick is a freelance writer and also authored three fitness and exercise books, dozens of e-books, thousands of articles, and several fitness videos. He’s not just an armchair fitness expert; Patrick practices what he preaches! He has competed at a high level in several sports, including rugby, triathlon, rock climbing, trampolining, powerlifting, and, most recently, stand up paddleboarding. When not lecturing, training, researching, or writing, Patrick is busy enjoying the sunny climate of Cyprus, where he has lived for the last 20-years.

One Comment on “What is EPOC and How it Accelerates Fat Burning”

  1. Pingback: 7 Benefits of Fasted Cardio (Great for Fat Loss!)

Leave a Reply

Your email address will not be published. Required fields are marked *