Cardio Intensity for Fat Loss

Written by Yasar Shahzad Wednesday, 07 July 2010 19:13

Cardio Intensity for Fat Loss

Low Intensity Exercise - The Myth of the Fat-Burning Zone in Cardio Exercise

One myth that has pervaded the fitness world for a long time is that low intensity cardio exercise burns more body fat than high intensity cardio exercise. This theory suggests that once your heart rate rises out of the "target fat-burning zone," you cease to burn fat and you burn mostly carbohydrates. Therefore, the theory goes, the best way to lose fat is low intensity cardio exercise.

This myth prompted many personal trainers and exercise organizations to promote low intensity cardio training as the ideal way to lose fat. Their advice: “Exercise at a low intensity for a long duration for fat loss.” Unfortunately, they are dead wrong. If this were true, we could extend the low intensity fat-burning zone theory to its logical conclusion and say that sleeping for twelve hours a day is the ultimate fat burner because when you’re sleeping (a very low intensity activity indeed) you’re burning the greatest proportion of fat to carbohydrate. The problem is, because sleeping is so “low in intensity,” it hardly burns any calories! If the intensity of an activity is too low, you don’t burn enough total calories to have any impact on fat loss.

Why Moderate to High Intensity is Better

At lower intensities, you burn a greater percentage of calories from fat than carbohydrates, and at higher intensities you burn a greater percentage of calories from carbohydrates. High intensity cardio exercise can use as much as 65% of the body's energy needs in the form of carbohydrate. The most important issue for fat loss is not the ratio of fat to carbohydrate burned, but the total number of calories burned and high intensity cardio exercise burns the most calories!
The lower the intensity, the lower the total number of calories burned and the higher the intensity, the greater the number of calories burned. High intensity cardio also raises your metabolic rate after the workout to a much greater degree than low intensity cardio. That’s why high intensity cardio is better, provided that you can maintain it for a long enough duration to burn an appreciable number of calories.

Intensity of Cardio Exercise

The laws of fat loss are relatively simple: (1) Work out longer and you'll burn more calories and lose more fat, and (2) work out more often and you’ll burn more calories and lose more fat. Following this line of reasoning it would make sense that; (3) if you work out harder you’ll also burn more calories. This is true, but only up to a point. As you push harder and harder, a level will be reached where if the intensity goes any higher, you won't be able to sustain the activity long enough to burn much fat. You’ll become fatigued before you can finish your workout. Therefore, selecting intensity, that’s not too light but not too hard is critical. This is known as your "training zone," "target zone," or “fat-burning zone.” This optimal zone for fat burning and cardiovascular conditioning is generally between 60% and 80% of your functional capacity or 70-85% of your age predicted maximum heart rate.