Good news: The effects of a tough workout may last a lot longer than the time you’re in the gym. Thanks to excess postexercise oxygen consumption (EPOC)—also known as the “afterburn effect”—your body may continue to torch calories for up to 36 hours after you stop exercising.
But you don’t reap these benefits from just any exercise. To get the true afterburn effect, fitness pros stress that you have to work out for 15 minutes at greater than 70% of your VO2 max, which stands for maximal oxygen uptake and refers to the amount of oxygen your body is capable of utilizing in 1 minute. This roughly equates to keeping your heart rate at around 140 beats per minute in that time frame. “The more intense the workout, the more oxygen your body will consume afterward and the more calories you’ll burn in return,” says Brandon Mentore, a strength and conditioning coach in the Philadelphia area.
Classes like Orangetheory Fitness are focused on just that, with participants dashing between the treadmill, weights and a rowing machine to produce 12–24 minutes of training at 84% of their maximum heart rate (or the “orange zone,” as it’s known in the class).
“Doing high-intensity interval training and strength training yields the greatest amount of ‘afterburn,’” says Mentore. “It doesn’t necessarily apply to less intense and more endurance-oriented exercise, like walking or doing a cardio machine at a comfortable pace.”
While the specific results of the afterburn effect varies from person to person, experts say you may burn up to an additional 150 calories in the 24–36 hours following your workout. “It can give you a little added boost. One hundred extra calories burned each day is about a half-pound per week or equivalent to walking 1–3 miles,” says Wes Ferguson, a celebrity trainer in Los Angeles.
That’s not to say you can stuff yourself silly after an extra-tough workout. “The afterburn effect isn’t substantial enough so that you can just pig out on anything over the next few hours,” says Ferguson. Instead, snack smart with a mix of complex carbs and protein, a powerful combo that helps boost muscle recovery, reduce soreness and build strength.
Whatever you munch on, practice moderation, stresses Ferguson. “You can’t say, ‘I worked out, that means I get ice cream as a reward!’ Then you’ll just undo everything.”