High-intensity interval training is a fabulous tool for fat loss. An interval is a brief bout of intense physical activity (think sprint) followed by a longer period of lighter exercise. For example, you might run all-out for 15 seconds, then rest for 30 seconds - that's one interval.  The New York Times ran an article about exercisers who completed just 6 MINUTES per week of intervals and got the same results (if not better) than those who had worked out for 5 hours! Could it be that most of us are spending more time than we need in trying to get slim and fit?

What do I mean by intense exercise? Firstly, you must get clear on your level of effort. If we assume that an effort level of 10 would be the equivalent of running away from a tiger then you will realise that an intensity of level 8 still represents quite a substantial physical demand. This is probably as much as you will muster when I ask for your all-out effort. Unless I unleashed that tiger of course.

If you are willing to spend 20 minutes three times a week on interval training the results in your body weight, shape, fitness and fat levels will be nothing short of amazing. Before you get too excited don't overlook the risk of injury - intervals must be preceded by an adequate warm up and also a strong base layer of fitness. So if you are unfit – and let's be honest here – then make sure you spend a few weeks following a traditional jogging or cycling programme (or similar) before experimenting with intervals.

Ready to go? Try this:

1 Warm up: Five minutes of jogging or cycling at around level 3 of your all-out effort.

2  Run or cycle for 10 - 30 seconds (depending on fitness) at about level 8 of your all-out effort.

3  Slow down to level 3 of your all-out effort for 30 - 90 seconds.

4  Repeat steps 2 and 3 between 3-5 times.

5  Finish with 15 minutes of gentle jogging or cycling to cool down.

Do observe your rest days - it's crucial to have sufficient time off in between your interval training sessions to allow your body to recover (especially when you begin to increase distance or time). You will run faster with adequate rest. Remember, intervals are intense – they are demanding. They can feel like hell. You will pant and curse and grimace like never before.  But if you want guaranteed results – here is your answer.