When you're trying to burn fat, there's one form of exercise you'll start hearing a lot about: high-intensity cardio workouts. We often call these workouts HIIT, aka high-intensity interval training, because it's a kind of exercise should be done all-out, as hard as you can go, at 80 to 95 percent of your maximum heart rate. "The higher the better," said exercise physiologist Tom Holland, MS, CSCS, Bowflex fitness advisor and author of The Micro Workout Plan.
Most people can't sustain that intensity for a long period of time, which is why trainers break it up into sections: work intervals and active rest intervals. You go hard then recover, in short bursts of cardio and rest. This structure allows you to work harder and ultimately burn more calories than you would if you were trying to sustain that pace the whole time.
HIIT can be confusing though, because how should you actually do it? Run? Cycle? Bodyweight exercises? You have plenty of options when it comes to high-intensity cardio, and you want to choose the one with maximum fat burn. But first, let's talk about how HIIT burns so much fat in the first place.
Does High-Intensity Cardio Burn Fat?
"HIIT is extremely effective for fat loss for two main reasons," Tom told POPSUGAR. For one thing, you burn more fat during interval workouts than during steady-state training; one 2019 review found that people burned nearly 29 percent more fat through HIIT than through moderate-intensity, steady-state workouts.
Then there's the EPOC effect, aka excess postexercise oxygen consumption. After working out, your body is in an oxygen deficit that it has to work to make up. So even though your workout is over, you're still consuming oxygen at a higher rate, which requires more energy, which means you're burning more calories. The EPOC effect kicks in the hardest after HIIT, and while it doesn't last for hours and doesn't burn hundreds of calories, it's still helping you get more bang for your buck.
What's the Best High-Intensity Cardio For Fat Loss?
Good news: you can use multiple types of high-intensity cardio to burn fat. They'll all be effective, especially if you're using the HIIT format of going all out, followed by a rest period. Some examples Tom recommended: running, cycling, rowing, and plyometric bodyweight exercises.
Even more good news? Whatever mode of cardio you choose, Tom advised keeping both the intervals and the overall workout short, because that allows you to go harder during the work sessions. "The harder the work interval, the more calories you will burn both during the workout and potentially afterwards as well," Tom explained. Lack of time is typically the biggest barrier to exercise, he added, which makes HIIT "the perfect solution."
How Often Should I Do High-Intensity Cardio to Burn Fat?
High-intensity cardio sessions are hard on your body, so aim to do them on non-consecutive days of the week. This gives you time to recover, which will ultimately help you burn fat: the fresher your body is when you head into a HIIT workout, the more effort you can put in! Tom recommended the following as a weekly workout structure, with a maximum of three HIIT days per week:
- Monday: HIIT
- Tuesday: steady-state
- Wednesday: HIIT
- Thursday: steady-state
- Friday: HIIT
- Saturday: steady-state
- Sunday: rest day
HIIT might be the biggest fat-burner, but low-intensity steady-state cardio, aka LISS, has its place too. It's good for your heart, can be done at any fitness level, and is essentially active recovery from your HIIT workouts. "Like everything else in exercise, variation is one of the major keys to success, both physiologically as well as mentally," Tom said.
If you're raring to get started, try this HIIT treadmill workout, a 15-minute plyometric bodyweight circuit, or a high-intensity cycling workout that'll burn fat and keep you from getting bored. Any one of these forms of cardio can help you burn fat. You just have to find one you actually enjoy! If you like the exercise you're doing, you're more likely to stick to it, which will ultimately help you burn more fat — and have more fun while you're at it.