Afterburn effect (EPOC)
The afterburn effect is the increased energy expenditure after exercise – it's real, but at 6 to 15% of the calories burned in the workout, it's smaller than its reputation.
Ausführlich erklärt
After exercise, your metabolism keeps running at a higher level for a while: your body refills its energy stores, repairs muscles, brings your temperature and heart rate back down and clears lactate (a by-product of intense exertion). This extra energy used after training is called the afterburn effect – scientifically known as EPOC (“excess post-exercise oxygen consumption”).
How big it is depends mainly on intensity. After a gentle walk, it's over within a few minutes. After hard interval training or heavy strength training, energy use stays slightly raised for several hours. A review (LaForgia et al., 2006) puts the afterburn effect at around 6 to 15% of the energy burned during the workout. So a 300-kilocalorie workout brings roughly 20 to 45 extra kilocalories – about as much as half an apple.
Advertising promises of “fat burning around the clock” are therefore exaggerated. The afterburn effect is a nice bonus, but it's no substitute for the energy you burn during the workout itself – let alone for a balanced diet. If you walk briskly for 30 minutes, you burn more in that half hour than a four-minute workout “afterburns” in the 24 hours that follow.
Intensity is still worth it – for other reasons: intervals and strength training build muscle, improve insulin sensitivity (how well sugar gets from the blood into your cells) and boost fitness more than steady-paced training. The long-term effect of more muscle mass on your basal metabolic rate is the real “afterburner” – it just works over months.
For weight loss, this means: move in a way you enjoy and will keep up regularly. A mix of plenty of gentle activity, some strength work and the occasional burst of intensity works better than chasing the biggest afterburn effect.