Excess Post-exercise Oxygen Consumption

There appears to be some misunderstanding about whether or not exercise actually continues to burn calories after you're through with your workout. The answer, as near as science can tell, is an unequivocal "Yes".

The scientific term for the phenomena is EPOC - Excess Post-exercise Oxygen Consumption. At the finish of your workout, your body attempts to return to it's previous resting state - as well as adapting it to the exercise performed by repairing muscles, building new muscles, increasing bone density (if you lifted weights!) and refueling those muscles by replenishing glycogen stores.

Glycogen is the form of sugar that's actually stored in your muscles. It's the "gas" for your "engine". It powers the brain, heart, other involuntary muscles - just about everything.

During exercise, when more energy is needed, your body converts fat into free fatty acids that get dumped into the blood stream where they can be used as fuel (along with the glycogen). At the end of the workout, they help energize the repair process, helping the body rebuild and recover. Any unused free fatty acids are reconverted back into fat for later use.

(Or storage. Sigh.)

Studies have shown that the EPOC effect is greatest immediately after exercise and slowly tapers away. This raised metabolism, in one study, was still observable as long as 38 hours after the workout, but in general the effect has diminished substantially by between 3 to 14 hours after your exercise.

Anaerobic exercise seems to cause EPOC to a greater extent than aerobic exercise does. That means that lifting causes it more than running. And, it appears that increasing either the length of time spent exercising or the intensity of the exercise (or both!) increases the EPOC effect.

Bottom line? Exercise not only burns calories NOW, but it continues to burn them at a better than resting rate for several hours after your workout. And... stored fat IS used for fuel during your exercise - but whatever isn't needed for muscle repair and rejuvenation is sent back into storage.