High Intensity Interval Cardio Training (HIIT)
For all those interested in efficient fat loss
Ingrid Marcum writes:
The reason that High Intensity Interval Training works better for fat loss is this: When you do a cardio session at the same pace the whole time, your body goes into what is called steady state. This means that your body has adjusted itself to the speed you are going and tries hard to conserve energy (calories). You will be able to avoid this and burn more calories and FAT by doing the interval training.
The easiest way that I tell people to do it is to start off at a good pace for 5 minutes. Then take up the intensity on the machine and go as hard and as fast as you possibly can for a minute and then bring it back down for a minute or two — however long it takes for you to recover enough to do it again. ANY cardio machine will work — I like the treadmill and the elliptical trainer the best.
Another easy way to introduce yourself to this kind of cardio without killing yourself right off the bat is simply to keep changing your speed and intensity level every two minutes or so — go up and down — challenge yourself. This will "trick" your body into burning more calories since it can not achieve steady state.
When it comes to the heart rate question— whether to stay lower or higher — this is your answer. At a lower % of max heart rate (65%), a larger percentage of calories burned come from fat than at a higher heart rate (75-85%). HOWEVER, despite the percentages, you will burn more total calories and therefore more total fat calories at a higher heart rate.
What's all this about body fat?
Understanding Body Fat Percentages
Body fat measurements and the measuring tape are recognized as superior methods for measuring "weight loss". When one declares that they want to "lose weight", what they often mean is that they want to lose fat. So, now that you've had your body fat percentage measured, what does the number really mean? 
First, your body fat percentage is simply the percentage of fat your body contains. If you are 150 pounds and 10% fat, it means that your body consists of 15 pounds fat and 135 pounds lean body mass (bone, muscle, organ tissue, blood and everything else).
A certain amount of fat is essential to bodily functions. Fat regulates body temperature, cushions and insulates organs and tissues and is the main form of the body's energy storage. The following table describes body fat ranges and their associated categories:
*General Body Fat Percentage Categories
| Classification | Women (% fat) | Men (% fat) |
|---|
| Essential Fat | 10-12% | 2-4% |
|---|
| Athletes | 14-20% | 6-13% |
|---|
| Fitness | 21-24% | 14-17% |
|---|
| Acceptable | 25-31% | 18-25% |
|---|
| Obese | 32% plus | 25% plus |
|---|
*American Council on Exercise
Knowing your body fat percentage can also help you determine if your weight loss goals are realistic. Remember, weight loss doesn't always mean fat loss.