Once the fitness trend that dominated the 2010s, high-intensity interval training remains an efficient way to burn calories, improve cardiovascular fitness and support fat loss. Experts explain why it works and share simple HIIT exercises you can do at home.
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It was the workout trend that dominated the 2010s, and while HIIT may have lost its fitness-craze status, it remains one of the most efficient ways to exercise. We look at why high-intensity interval training can support fat loss and how you can do it in the comfort of your own home.
As one of millions of HIIT fans, it has been a consistent part of my exercise routine for the last decade – and for good reason. While fitness trends may come and go, HIIT has stood the test of time because of its many health benefits, from improving speed, power and athletic performance to supporting fat loss.
It was also a lifesaver for me, both physically and mentally, during the Covid lockdown. Its short duration meant I could fit it around my job and homeschooling, while at a time when I was eating and drinking more, I loved the fact that it helped me manage my weight. The brief bursts of hard exercise also helped reduce my stress and lift my mood.
So, what is it about HIIT that can support fat loss, and how can we do it at home? I asked the experts.
Why is HIIT effective for fat loss?
According to Anwen Davies, a certified personal trainer and gym and fitness product developer at Net World Sports, HIIT can be effective for fat loss for several reasons. This includes helping to create an energy deficit: when you expend more energy than you consume, it can lead to a reduction in body fat.
“HIIT genuinely does earn its reputation as a fantastic workout style for people who are trying to lose weight. But I would say it is less about the actual workout and more about being efficient,” she explained.
“That said, HIIT works best as part of a bigger picture than a standalone solution. Ultimately, fat loss comes down to being in a calorie deficit, and pairing HIIT with some strength training and a sensible diet is a good idea.
“You are alternating short bursts of maximum effort with brief recovery periods, and that combination keeps your heart rate elevated throughout the session in a way steady state cardio just can’t keep up with.”
How the HIIT ‘afterburn’ effect works
“One of the biggest benefits is the ‘afterburn’ effect on your body, which may sound weird but it is your body continuing to burn calories at a high rate for hours after you finish, because it’s working to recover and repair.
“It’s also just incredibly time efficient, as if you are like me, working the usual 9 to 5, you can get most sessions done during the evenings as they usually take around 20 minutes.”
Performance coach and osteopath Kurt Johnson, from One Body LDN, also highlights HIIT’s ‘afterburn’ effect.
“The big reason why HIIT works so well is actually about what happens after the session. When you push through short bursts of intense effort followed by brief recovery periods, your body has to work harder to restore itself to its resting state,” he explained.
“This is known as excess post-exercise oxygen consumption, or EPOC. You continue using more energy for a while after HIIT, so you keep burning calories. Compare that to a steady-state cardio, like a 45-minute jog, and you don’t get the same metabolic disturbance, meaning the calorie burn largely stops when you stop moving.”
HIIT can deliver results in less time
“One systematic review (Scientific Reports) looked specifically at recreationally active women and found HIIT produced a significant reduction in body fat percentage, alongside meaningful improvements in VO2 max and peak oxygen uptake, across interventions as short as two to sixteen weeks.
“And for women who don’t have an hour to spend on a treadmill, many of the routines actually involve just three sessions a week, which can be fitted into a busy schedule without having to carve out a huge chunk of your day.”
Can HIIT help you maintain muscle?
Johnson adds that HIIT also tends to be kinder to your muscle mass than long steady-state sessions, particularly when it includes explosive, strength-based moves such as squat jumps and burpees.
“The more muscle you carry, the higher your resting metabolic rate, so you’ll burn more calories even when you’re not exercising. That’s a big reason why interval training often beats pure cardio for women who want to lose fat and tone up, rather than just watching the number on the scale drop.
“Hormones matter here too. Short, intense efforts stimulate a greater release of growth hormone and catecholamines compared with lower-intensity, longer-duration exercise, both of which help mobilise fat stores for use as energy.
“Combine that with the fact that HIIT genuinely challenges cardiovascular fitness in a way many find more engaging than spending 45 minutes staring at the same treadmill screen, and you’ve got a method that ticks the physiological and psychological boxes.”
The best HIIT exercises to do at home
Another benefit of HIIT is that you can do it at home without any specialist equipment. Below, both experts recommend their most effective bodyweight exercises.
Anwen Davies’ 20-minute HIIT workout
“Trust me when I say, you don’t need equipment for HIIT sessions as your bodyweight alone is really enough if you push the intensity. Here are a few go to moves:
Burpees: A full body move that spikes your heart rate almost instantly, works your chest, legs and core all in one go.
Mountain climbers: Don’t worry, no mountain is required. This workout is great for your core and cardiovascular fitness at the same time.
Squat jumps: Builds explosive power in your legs while getting your heart rate up quickly, a great one to superset with a slower strength move.
High knees: Simple but done at genuine effort it’s one of the quickest ways to spike your heart rate in a small space.
Plank to push up: Works your core and upper body, and because it’s a bit more controlled, it’s a good one to include between faster, more explosive moves.
“A simple structure to try is 40 seconds of work, followed by 20 seconds of rest, cycling through five exercises for four rounds, that’s a full 20-minute session. This is the best way to get the most out of HIIT, and if you put the effort in, you will get the results you want and much more.”
Kurt Johnson’s five-move HIIT circuit
Squat jumps: “Thirty seconds of explosive squat jumps works the largest muscle groups in the body (quadriceps, glutes, hamstrings, calves, core, hip flexors), meaning a bigger metabolic demand for very little time invested. If jumping is not possible, fast squats are a perfectly good swap.”
Mountain climbers: “These raise your heart rate quickly while working your lower back muscles, the entire core, shoulders, triceps, and lower body muscles like the quadriceps and hip flexors. They’re low-impact enough to repeat through a circuit without wrecking your joints and are easy to modify by slowing the pace down.”
Burpees: “They’re essentially a squat-plank-jump movement, recruiting almost every major muscle group in a single rep. Nobody’s favourite, but they pack a lot.”
High knees: “Perhaps the simplest way to get your heart rate up between harder exercises. Use them as active recovery too, dropping the pace when you need to ease off without stopping completely.”
Plank to shoulder tap: “This brings some core stability into the session with the anti-rotation challenge on top of the cardiovascular benefit, particularly as you have to resist twisting your body while moving one hand at a time.”
