The reason high-intensity cardio works to burn fat faster is that your body is being asked to produce a lot more energy than it has stored in order to deal with the intensity of the workout.
It does this by burning off those fat reserves it has been keeping for a rainy day. Not only that, but your body then has to keep producing energy even after you stop as it needs that in order to start repairing the muscles and settling your body after your strenuous workout.
It is also important to point out that this particular type of workout focuses on burning a different type of fat than what you would get doing a lower intensity cardio workout such as brisk walking.
The problem with lower intensity cardio work is that it only gets your heart working to around %60 of the maximum heart rate.
This is not high enough for optimal fat burning. Instead, you will only burn off the easy stuff, but the harder fat will still be there, so by increasing the intensity you burn off both types. This results in quicker weight loss.
When doing a high-intensity cardio workout to burn fat faster, lactic acid builds up in the muscles. This results in the muscles becoming tired and burning. You can learn to anticipate this and push through. You can then work out for longer periods of time. This results in more calories and fat being burnt off and that weight disappearing.
This approach results in improving the sensitivity of your body to insulin.
The outcome of this is that the muscles are going to absorb the glucose, and use it to repair themselves and to get energy, rather than it being stored as fat.
An active lifestyle, that includes both low-intensity and high-intensity cardo workout routines will raise your metabolism. Even when you are at rest.
