When facing suddenly snug jeans, most men default to the treadmill. There’s a pervasive myth, embedded by those sociopath PE teachers who marshalled you across country, that the most effective way to burn fat is cardio. Endless, uninspiring cardio. The kind of exercise that stops people ever attempting exercise.

Not that we’re blaming PE teachers for the obesity crisis (thanks, Mr Rowan). But the indoctrination that more miles run means fewer inches around your waist is tough to overturn.

It’s not that cardio doesn’t work. It’s just that it’s inefficient. Put simply, running only burns fat while you’re running. So you run longer, run further, get bored, give up. But if you switch to shorter bursts of heart rate-spiking exercise, not only do you get the same immediate calorie burn in less time, you increase your metabolism for hours afterwards. It’s an effect known as excess post-exercise oxygen consumption, or EPOC.

“That means you continue to burn calories much quicker, up to 48 hours after the workout itself,” says Fitness First trainer Anthony Murray. So your love handles are still evaporating when you’re plonked, exhausted, on the sofa.

Hard work, however, is key. Unlike that amble around the park, high intensity interval training is, as the name suggests, intense. By switching between bursts of exercise at 100 per cent effort, then brief rest periods, you force your heart and muscles to work at their maximum capacity. Which translates as more results, in less time.

In fact, a study in the American Journal of Physiology found that a 20-minute HIIT session boosts your VO2 max – a key marker of fitness – more than longer cardio sessions. Oh, and because a circuit like the one below hits every muscle in your body, you’ll torch more fat and firm up what’s underneath it.

Blast through Murray’s HIIT circuit, which demands no equipment other than your bodyweight (and whole load of sweat) and in just 20 minutes you’ll do more to burn off that beer belly than any hour-long jog. The only challenge will be working out what to do with all that time you’ve suddenly freed up.

Warm-Up

Target: Whole body, specifically heart rate and legs.

Inchworms

Start out with your body positioned as if you’re about to do a press-up. Facing downward, with your body in a straight line and your hands and feet shoulder width apart, walk your hands back to your toes, letting your back rise as you go.

Once you touch your toes walk your hands back out until your body is in starting position. Repeat 10 times.

Knees To Chest

Lie flat, keeping your head and back on the floor. Wrap your arms around your knees, keep your ankles together, and lift your feet off the floor so your knees come to your chest.

Move your legs back to starting position and repeat this motion 10 times.

Side Lunges

Clasp your hands together in front of you and stand with your feet roughly shoulder width apart. Bend down and shift your weight, so one leg is bent and one is extended straight to your side.

Make sure you are bending your knees and lowering yourself back into a semi-sitting position. Return back to standing position and repeat six times on each side.

The Circuit

Now the blood’s moving, you’re ready to work. Perform each move for 30 seconds, at 100 per cent intensity, then take another 30 seconds to catch your breath before moving on to the next exercise. After the mountain climbers, return to the high knees, and repeat the entire circuit for four rounds total.

High Knees

Target: Legs and glutes.

Stand with your feet hip width apart, with your arms hanging down at your sides. Jump from one foot to the other, lifting your knees as high as you can. Your arms should either the follow the same motion as your legs or you can air punch.

X-Jumps

Target: Glutes, legs, obliques.

Stand with your legs shoulder width apart, leaning slightly forward, with a straight back. Bend your arms to 90 degrees and squat down so your thighs are parallel to the floor.

Jump up and, as you land, touch your right ankle with your left hand. Jump up, land in your starting position, and touch your right hand to your left ankle. Repeat.

Starship Burpees

Target: Entire body, with focus on arms and legs.

From standing, bend your knees and place your hands in front of you on the ground. Kick your legs back, like you’re going to do a press-up.

Bring your knees back in, then pop into the air, performing a star jump. When you land, squat down and repeat.

Jumping Jacks

Target: Arms and legs.

Start with your legs together and arms by your sides. Jump up and spread your arms and legs out. Land back in starting position and repeat.

Mountain Climbers

Target: Upper arms, legs and core.

Start in a plank position, ensuring that your core is engaged and your hips remain parallel with the floor. Bend one knee at a time into your chest as far as you can go, then repeat with the other leg.