By Mark Mayes Cert. Health Fitness Specialist

What is the best way to burn fat low intensity for a long time or high intensity for a shorter time?

This has been an area of controversy and misconception for a long time. Mainly because the two concepts are not fully explained.

 Lets start at the beginning as to why these concepts are used. The human body is a very complex machine and just like any other machine it needs fuel to perform activities. The types of fuel the body uses are fat, carbohydrates and proteins. The body uses each fuel differently and each one is an important part for proper function of the body. Fat is not as bad as it is made out to be, it is needed by many systems of the body and it is a high-octane fuel source. Fat gives the body the biggest bang for the buck when it comes to energy production. Fat is a slow burning fuel that produces large amounts of energy, where as carbohydrates and proteins are faster burning fuels with less energy produced.

The problem is when the fuel intake is not equal to the fuel used. Therefore, the body starts to store the excess fuel; all three-fuel sources over time can be converted to body fat.

When a person wants to lose weight (excess fuel) they must produce a large amount of energy, this energy is measured by calories. Fat requires the most calories (9 cal.), Carbohydrates and Protein (4 cal.). This is where the controversy starts in order for a person to decrease body weight, most research shows that a large number of calories need to be burned per day.  And where the calories come from does not matter. If a person only wants to burn fat calories it takes a long time (duration) at a lower intensity so as not to use as many calories from any other fuel sources. So after an hour a person 1 may burn 500 calories, 80% of the calories coming from fat. This sounds good 80% fat production.

Now lets say person 2 works at a higher intensity for 45 minutes and this person burns 900 calories and 60% of those calories are from fat. The higher intensity method does not sound as impressive until you do the math. The higher intensity workout may not use as many calories from fat as far as the percentage, but the over all calorie expenditure is more. Most research to date in the area of weight loss supports the higher intensity for weight loss.

The next question is “How do I determine the right intensity for burning the most calories”.

The easiest way to determine the intensity (Target Training Zone) is to use the following formula:

Target Training Zone (TTZ)

– 220 minus your age = Maximum Heart Rate (MHR).

-Multiply .65% times MHR = low end of TTZ

-Multiply .85% time MHR = top end of TTZ

In order to burn the most calories it is best to keep ones heart rate in the target training zone for twenty minutes, building on the time as you get in better shape. 

To summarize a person burns more calories from fat at lower intensity; in fact you are burning more fat than carbohydrates as you read this. But at a higher intensity one will burn more calories and more of those calories will come from fat even if the percentage is lower.