The Fat-Burning Zone Myth

You may have heard that if you go over a certain heart rate while doing cardio or aerobic exercises that you do not burn fat.

This is however an urban myth. It is one of those misconceptions that should be put to rest once and for all when it comes to fat burning aerobic exercises. The idea got its start in the mid 1990s when scientists reported that during high-intensity fat burning aerobic exercises, the body burned mostly stored carbohydrates for fuel, as opposed to burning stored fat as it did during lower-intensity activity.

The key word is 'mostly'.

Unfortunately a few unintelligent exercise instructors took the news and ran with it, encouraging people to pay for low-intensity "fat-burning" classes... classes that ultimately didn't help people much.

It is true that the body burns a higher percentage of calories from fat during more mellow exercise like walking and easy cycling... but the actual number of calories is very little.

When you pick up the pace for a higher-intensity cardio workout you burn a greater number of overall calories of both stored fat and stored carbs... and thus burned much more fat period.

For example, say a 140-pound woman performs either a fairly easy walk or a high-intensity jog. After 1 hour, she would have burned the following in total and fat calories:

Walk = 200 calories (75% fat for a total of 150 calories of fat)

Jog = 300 calories (60% fat for a total of 180 calories of fat)

Thus the higher intensity workout always burns more fat. Its really the result of your body drawing upon all available reserves to get as much energy to the muscles as it can.

NOTE! High-intensity aerobic exercises kick your metabolism into high gear even after you're done working out. That means that even after you stop exercising you are stilling burning calories because your blood is being pumped faster for a longer period in an effort to heal muscle tissue.

"When you exercise vigorously, you get a robust hormonal change, which causes your body to burn more fat during your recovery time," says Janet Walberg Rankin, PhD, professor of nutrition at Virginia Tech University in Blacksburg. Your metabolism also stays revved up five times longer after a vigorous workout than after an easy one. Over time, this can add up to burning an additional 100 to more than 200 calories a day.

High-intensity exercises are difficult to sustain, especially if you're just starting out. But practice makes perfect and you can build up more intensity and duration as you get better at it.

The easiest way to infuse intensity into your existing routine is to start adding 5 minutes of higher intensity exercises to whatever you are doing.