The last time you boiled a kettle of water, you probably noticed that the kettle (and contents) stayed hot long after you turned off the flame. The same thing happens with your body when you’re done with a tough workout. Often times, even though we’re already done with the heavy effort and onto the next task, our body continues to burn calories long afterward through the “afterburn effect,” otherwise known as excess post-exercise consumption (EPOC).

“It’s how your body recovers after a workout,” says Amanda Schreiber, a certified athletic trainer (ATC) at Bespoke Treatments in Seattle. “In order to recover completely, your body must replenish its oxygen, ATP, and creatine stores as well as remove lactic acid and repair of muscles. All of these tasks require energy and therefore burn calories.”

So even though you may be sprawled out on the couch ready to start your next Netflix binge, your metabolism is still stoked. Granted, not all workouts equal the same amount of caloric afterburn.

“The type of exercise, workout intensity, duration, gender, and level of physical fitness affect the amount of calories burned post workout,” says Schreiber. In other words, the higher your workout intensity, the more you will burn afterwards. High intensity interval training such as Tabata (20 seconds of work, 10 seconds of rest, for 8 rounds) creates the most ideal conditions for high caloric afterburn, says Schreiber.

It sounds good in theory, of course. But how many calories are we really talking about here? Runners and cyclists who participated in speed interval training burned between 45 and 65 calories within the first two hours following a workout, according to research in the journal Applied Physiology Nutrition and Metabolism.

So is 65 calories a total game-changer? From that “it’s only 65 calories” perspective, not so much. Think about the bigger picture, though. Over time (days, weeks, months) those 65 calories begin to accumulate, and hey, that’s a lot more than what you’d experience otherwise.

“Most of the afterburn will happen in the first 10 to 24 hours post workout,” says Schreiber. “A rather small amount compared to the total calories burned during the workouts themselves—but nothing to scoff at.” So if you’re looking to amp up your afterburn, now you know how to do it. Time to HIIT the gym.

Speaking of Tabata, here’s a 4-minute flow for you to try and here’s a thorough cheat sheet on what you should know about HIIT training.