The fat burning zone

The fat burning zone is between 55% and 85% of your maximum heart rate.

The theory goes as follows:

• If your heart rate is lower than 55%, then you are not doing much exercise and are not burning sugar or fat. This is your warm up and cool down zone.
• If your heart rate is higher than 85% of your maximum heart rate, then you are in your anaerobic/high intensity zone.  This zone places a high demand on the cardiovascular system and does not burn much fat.  It does however burn more glycogen (sugars / carbs stored in your muscles and liver) – usually from your last few meals. It can also make you hungry afterwards since your sugar levels have dropped.
• The Target Heart Rate Zone (65-85% of Maximum Heart Rate) is an area of moderate intensity activity that leads to improvements in your aerobic capacity and burns fat.  This zone provides many benefits for all fitness levels, including those who want to lose weight, those who are training for an athletic event, or those who are looking to have more energy and get fit.

How to calculate your fat burning zone

220 – Age = Maximum Heart Rate (bpm = beats per minutes)

Now take 55% and 85% of this maximum and keep within the range.

For example, for  a 30 year old:

1. 220 – 30 = 190bpm maximum
2. 55% of 190 = 104bpm and 85% of 190 = 161bpm
3. Maintain a heart rate of 161bpm and never fall below 104bpm.

Staying motivated and maintaining a constant fat burning effort

As with all exercises, your body gets use to each exercise and becomes lazy once it is use to doing the same machine.  This reduces the fat burning effect and demotivates a person as well.

To maintain top form, split your cardio training into 10 minute sessions on 3 different machines. For example: treadmill, stepper, cross fit machine and rower can be rotated  from day to day to offer different combinations of exercises.

You will be hitting different muscles and maximizing your fat loss without getting too bored.

The problem with the fat burning zone

Ok, it all seems easy and to achieve 85% is quite easy.

However, there is a problem, the lower the intensity, the lower the calories that gets burnt as well.

30 Minutes of Exercise	Fat Calories Burned	Glycogen Calories Burned	Total Calories Burned
Low Intensity Group (50%)	120	80	200
High Intensity Group (75%)	140	260	400

Let’s have a look at the table. If we look at the math, it would seem that 50% more effort (from 50% to 75% in intensity) is required to achieve a 14% increase in fat burning.

So it does seem to make sense that keeping at 50% is better than giving additional effort to burn a small additional amount of fat.

BUT.. there is something that we missed –

The Afterburn Effect

builtlean.com has explained it perfectly as follows:

“When you exercise at low exercise intensities, you burn very few calories after the exercise is completed. When you exercise intensely such as during a hi intensity workout, there is a metabolic disturbance that burns calories after the workout is completed. This is known as the afterburn effect.

In a study by Dr. Christopher Scott and the University of Southern Maine, the total calorie burn of low intensity exercise vs. high intensity exercise was examined. A low intensity exercise group cycled at a steady rate of 3.5 minutes. The higher intensity exercise group required three 15 second sprints as fast as the subjects could run.

What was the difference in calorie burn? Quite substantial.

The cycling group burned 29 calories vs. 4 calories for the sprinting group during the exercise. But when you take into account the calories burned after exercise, or the afterburn effect, the numbers look much different – 39 calories burned for the cycling group vs. 65 calories burned for the sprinting group. A surprising 95% of the total calorie burn occurred after the sprinting exercise! Keep in mind the cycling group exercised for almost 5x longer than the sprint group (3.5 minutes vs. 45 seconds).”

Training in bursts will offer the best results when it comes to shedding body fat.

Circuit training is an ideal place to do burst training. Give your maximum at each station for best results.

Or burn the desired amount of calories by using the “fat burning zone” method, and finish off with 2 or 3 minutes of burst training to keep your body in the “fat burning zone” for longer.

• Walk on the treadmill with 15 second bursts of running at top speed, slow down for 15 seconds. Continue for between 2 and 3 minutes.