What if there was a way you could burn fat, improve muscle tone and narrow your waistline whilst you slept? Sounds like the dream workout right? Well the great news is there is a way and it doesn't involve any untested 'wonder' drugs, magic formulas or sleep walking treadmill situations.

These stellar results can be achieved via a training technique called 'high intensity interval training' (HIIT), a workout method that improves body composition and cardiovascular health.

And in even better news, HIIT doesn't involve hours of mindless pavement pounding in the hope of seeing a slimline reflection in the mirror. HIIT involves working at a high intensity over a short period of time; you can get incredible results in just 90 minutes per week.  

Image: Tory Sport

Plus it's backed by science, studies have found HIIT to be more effective for losing fat than steady state exercising, such as jogging.

But the truly outstanding benefit of this intense exercise method is the effect on the body once the training sesh is complete. When you do a steady state activity like jogging, you burn cals while you're jogging, but when you stop, the cal burning stops, by contrast HIIT elevates the metabolism for many hours and even days after training, which means you'll burn calories in your sleep from that morning's (or even yesterday's) HIIT session.

So how to do this dreamy workout? No equipment needed, just access to a park, a set of stairs or a hill and an understanding of a few bodyweight exercises. Plus remember the key is that exercises are done at a very high intensity. During 'work' phase you should be too out of breath to talk, the rest phases can still be active but passive enough to give the body an opportunity to recover.

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A HIIT session should consist of a warm up of five-to-ten minutes to reduce the potential for injury. Then for the workout, alternate high intensity intervals of between 30-120 seconds with rest intervals of a similar length. The total workout (not including warm up or cool down) should be no longer than 20 minutes. You should finish with a five minute stretching cool down.

Some exercises for your HIIT workout include: 400m sprints, hill climbs, cycle sprints, box jumps, burpies, kettlebell swings or battling rope waves. Stability exercises such as flat and side planks are brilliant for the rest periods.

Dan Henderson is the co-founder of The Australian Institute of Kettlebells and the Functional Training Institute (where Dan trains the trainers). 
You can find Dan at: functionaltraininginstitute.com  
Insta: @functional_dan

The secret to losing weight while you sleep