The Afterburn Effect And Fat Loss

Does the afterburn effect really help you lose weight? Not likely, but the misconception still makes the rounds.

The Afterburn Effect Explained

The good news is that the afterburn does exist.

The bad news is that it is very unlikely to have an effect on your weight or fat loss.

Worst of all, too heavily relying on it could entirely damage your weight loss plans:

En Detail

I know the matter is complicated, so let’s recap. The three acronyms we are working with here are “BMR”, “TDEE” and “EPOC”:

• BMR stands for Basal Metabolic Rate (the amount of energy your body burns when you do nothing).
• TDEE is the Total Daily Energy Expenditure (which is the BMR plus what is burned when you do stuff).
• EPOC (Excess Post-Exercise Oxygen Consumption) finally is what is colloquially called the “afterburn effect” – the energy that is burnt because your body remains excited for a while after you did stuff, especially exercise.

EPOC’s Existence Makes Sense

In a way the existence of EPOC / the afterburn effect makes sense, doesn’t it? I don’t know about you, but when I finish a running session where my pulse was around 150 bpm, it doesn’t go back to 75 right at the moment where I press “Stop” on my watch.

Usually when I get back home, drop down on the couch and drink something, I can for the next 15 minutes or so feel my heart go boomboomboom and then boom-boom-boom until everything is apparently normal again. That my heart rate will be higher for even longer, without me noticing it, is likely.

But the big question about this was not if EPOC really existed, only how much it really burns.

Afterburning From 1919 To Now

As said in the video, most research that saw huge effects of EPOC was done in the fifty or so years after Harris and Benedict published their formula in 1919. Often these studies confused how many calories were burned and by what, as at that time laboratories didn’t have the necessary equipment – much of it didn’t exist yet.

But once the methods of measuring energy expenditure became better, the real magnitude of the afterburn effect was more clear. Consider this more recent research:

• Japanese researchers put a 11 men in a metabolic chamber (a room where their burned calories can be completely controlled and measured) for 72 hours and had them do moderate or vigorous exercise. They found that the afterburn effect was so small that it didn’t need to be added when calculating the TDEE.
•  A German study found that the afterburn effect “after usual fitness training does not contribute significantly to weight loss” (PDF).
• To make it big enough, the intensity would have to be so high that untrained, overweight individuals wouldn’t be able to sustain it, another paper found.
• The same paper also concluded that even at high intensities, the percentage of calories burned from the afterburn effect does not go further than 15%. Which means that if you managed to run at a very high intensity and burned 300 kcal, a mere 45 kcal would come from the afterburn effect.

One Study To Rule Them All

To be fair, there was one recent study that found a significantly higher contribution of the afterburn effect to the TDEE. A huge difference: around 519 kcal burnt from 45 minutes of exercise, and a whopping 190 from the afterburn effect. Now that sounds like good news, doesn’t it?

But if we look more closely, we find that the researchers deliberately fed participants enough food to keep them in energy balance (they got enough food to not lose weight).

What if the afterburn effect is only this big when people eat enough food to keep their weight steady?  This would mean that even if that study was right, the afterburn effect would still be quite useless for anyone on a diet: you could burn a lot of calories with it, as long as you don’t try to lose weight.

What Should You Do?

Don’t be confused by all this. Mostly, the “afterburn effect” is just another of those currently popular fad concepts people try to sell you their fitness books or diet plans with. If you follow someone’s advice about the afterburn effect and don’t lose weight, it’s not your fault. That person may have simply relied on research outdated by half a century.

Your most reliable advisor when trying to lose weight is your scale: if you overestimate the calories you burn by too much, you won’t lose weight. Readjust and weight loss success will be yours.

Picture courtesy of the U.S. Department of Defense.