HIIT & Exercise: How Can I Burn More Calories?

A: If calorie burn is your priority, and especially if you’re pressed for time (which pretty much includes everyone), you want to get as much mileage out of your workouts as possible. That means exercising smarter and harder, but it doesn’t always have to mean longer workouts. The plain truth though, is that the more time you spend being active, the more calories you’re going to burn.

You may have read about high-intensity interval training (also called “HIIT”), in which you alternate periods of intense effort with active recovery. Many people like HIIT (also called Tabata) because it’s a real time-saver; a typical workout lasts just 15 to 20 minutes. During HIIT training you might do 30 seconds of all-out effort, going as fast and hard as you can while doing cardio (running, cycling, swimming) or circuit training exercises (squats or lunges, for instance). After the 30 seconds are up you take 10 seconds of “active recovery,” during which you’re still moving but you’ve dropped down to nearly a resting heart rate. You then repeat the same 30 seconds on, 10 seconds off, interval again and again for a set period of time.

HIIT is effective at making you more fit, but unless you do a lot of these peak-effort intervals it won’t burn tons of calories. In one study from Auburn University in Montgomery, Alabama, participants did a workout of 20-second bouts of high-intensity work followed by 10 seconds of rest and repeated the intervals eight times during a four-minute period; they burned 13.5 calories a minute. That’s definitely impressive, but those who are overweight and/or not very fit won’t be able to keep up such an intense workout for long, so the actual calories burned during a HIIT training session probably won’t be huge. (And as mentioned above, duration will always trump intensity when it comes to calorie burn.) If, for example, you burn five calories a minute during a 60-minute workout, that totals 300 calories, which is obviously much more than the 54 calories someone would burn doing the four-minute HIIT workout in the Auburn University study.

It’s worth mentioning that all interval training is not created equal, either. An all-out-effort style trains your body’s anaerobic energy system; while intervals where you give less effort — say, 80% to 90% — train your aerobic system, which builds your aerobic fitness and makes your body more efficient at burning calories and fat. When you boost your anaerobic system—as athletes do — your goal is to get stronger, faster and more powerful. A well-rounded exercise regimen should include both types of exercise (though most of us are probably happy to shed more calories and fat during our workouts).

If you’re looking for more efficiency from your workouts you can combine HIIT and longer, less-intense intervals (say, 90-second intervals, with 60 seconds on and 30 seconds for recovery) or other cardio workouts with strength training, which also has a significant calorie-burning effect. If you include resistance training or circuits in your routine make sure to focus on technique; it’s easy to get caught up in trying to finish everything quickly, but with strength training accuracy and control trump speed.

Another option is to simply ramp up the intensity of your regular workout routine by making it more challenging. For example, walk or jog on an incline instead of a flat surface, cycle at a higher gear so there’s more resistance or swim laps with ankle weights. Whatever you do, give it your all: The harder and longer you go, the more calories you’ll burn.