(Excerpt from bodybuilding.com)
Full article: http://www.bodybuilding.com/fun/wotw79.htm
For quite a while it has been accepted that low-intensity cardio was the best for burning fat. According to studies this method burned the calories primarily from fat. This has recently been disproved, as a new and exciting way to perform cardio has arisen.
The best cardio for burning off that stubborn fat will have you in the gym shorter than you’d expect. This cardio is called HIIT-High Intensity Interval Training. The concept is pretty simple.
You transition from low-moderate intensity intervals to very high intensity intervals. If you judge by the readout on the given exercise machine, you might assume that going at a low intensity for 30-45 minutes would burn more calories than 15 minutes OR LESS utilizing HIIT. This is not true, however, as many of the calories you burn come after you leave the gym (When performing HIIT).
15 minutes may seem to good to be true to lose weight, but it is not. However, you must keep in mind this is no walk in the park. This is very demanding, but extremely rewarding and time-saving. HIIT will support your metabolism so that you are burning calories later in the day. You will burn fat if calories out exceed calories in, and you will expend more calories by choosing HIIT.
HIIT can be performed on many different exercise machines, as well as outside or on the track. In all situations, make sure to warm up for about 3-5 minutes. Once you are ready to go, you will begin your intervals.
As a beginner start with 30 seconds at a moderate pace (approx 50% maximum effort) and after 30 seconds go as hard as you can for 30 seconds. Then repeat. If performing on an exercise machine other than the treadmill, make sure to rev up the intensity level so that it is challenging for you.
Complete a total of 5-8 intervals your first time. You will find it more difficult than it sounds. Once you are spent, take another 3-5 minutes to cool down. That’s all you have to do. Only 5-8 minutes of actual working sets, and you are on your way to shedding some serious fat.
If not done on an exercise machine, you can still apply the same concept. Simply run, jump, swim, or anything you desire, at the intervals proposed above.