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Fat Burning Zone

Suppose we could identify the exercise intensity that produces the highest fat oxidation rate. In that case, we could work out at this intensity and dramatically improve our body's composition.

Low-intensity sessions to burn off fat

There are two key variables that we need to know:

  1. Fatmax - the exercise intensity at which the highest rate of fat oxidation occurs
  2. Fatmax zone - the range of exercise intensities in which the fat oxidation rates remain within 10% of Fatmax


Researchers from Birmingham University's Human Performance Laboratory attempted to pinpoint the exercise intensities at which fat metabolism is maximised in a study[3] of 18 male endurance cyclists with a training background of at least three years. Their work found that the Fatmax Zone is between 68% and 79% HRmax.

Alternative research has suggested that when you cycle, swim, row or run at a modest intensity of only 50% VO2 max (about 69% HRmax), fat provides about 50% of the calories you need to keep going for the first hour or so. If you keep going after that, fat becomes even more generous, providing around 70% of the total energy after two hours and 80% or more if your work duration exceeds three hours. If you increase the intensity, then the Fat contribution decreases - at 75% VO2 max, fat provides 33% of the energy.


High-Intensity sessions - are just as good!

The implication of all this research (Anderson 2002)[1] is that if you wish to burn maximum amounts of fat, you should train in the 68 to 79% HRmax window. The reality is that if you train at higher intensities, you can burn just as much fat.

If you cycled along at 50% VO2 max, fat would provide about 50% of the energy needed to keep going. If you cycle along at 75% VO2 max, fat will provide 33% of the required calories. Thus, the slower workout sounds better from the fat breakdown perspective - or does it?

A moderately fit athlete exercising at 50% VO2 max generally consumes about 220 Calories during a 30-minute workout. If the same athlete works out at 75% VO2 max, 330 Calories are burned during the same period. Of course, 50% of 220 Calories and 33% of 330 Calories yield an equal number of calories cfrom fat - 110 Calories.

Interval work may be the solution

Australian Researchers at the University of New South Wales and the Garvan Institute studied 45 overweight women over 15 weeks. Three times a week, the ladies cycled for 20 minutes, sprinting in bursts of 8 seconds, followed by 12 seconds of easy cycling.

Professor Steve Boutcher, the team leader, stated that the women lost three times more weight than other women who exercised regularly at a continuous pace for 40 minutes. In the study, women were said to have lost weight mainly from their legs and buttocks.

It is unclear how it works, but interval training is far more responsible for getting the body to yield its fat.

Fat provides all your energy

If fat alone met all your energy needs, you would not break down carbohydrates during your workouts. As a result, your leg muscles would be amply and permanently stocked with glycogen (assuming that your diet contains a standard carbohydrate content). Each time you ate, the carbohydrate from your meal would be processed and transported to your muscles. Your muscle cells would say, 'No thanks, I do not need more carbohydrates. I am already full.' The surplus carbohydrate from your meal would be converted to fat. It looks like a no-win situation - as fast as you burn fat off, it is replaced.

An effective way to lose fat

Most exercisers are time-constrained and do not have hours to spend on low-intensity sessions. When time is limited, there is little reason to train in your Fatmax Zone. If your goal is to get leaner, the bottom line is that Fat Burners is the best way to achieve it.

The most effective way to lose body fat is to burn slightly more calories than you take in and continue this negative energy balance over an extended period.

Medium-chain triglyceride (MCT)

MCTs are a class of fatty acids frequently occurring in oily foods, which require less energy for uptake and storage in the body and are easier to digest and absorb than ordinary fats. Research indicates that the consumption of MCT oil (14-20grm/day - 112-160 calories) could be a useful addition to the diet for athletes trying to lose or maintain body fat. MCT oil is commercially available.

Coconut oil and Palm oil are naturally rich in MCT, but contain long-chain triglyceride (LCT). Studies have demonstrated a weight loss effect with an MCT/LCT mix - 14grm with a 12% MCT content (Hamilton 2008)[2].


  1. ANDERSON, O. (2002) You do have a fat burning zone, but do you really want to go there to burn off fat. Peak Performance, 164, p. 1-4
  2. HAMILTON, A. (2008) MCTs time to renew an old acquaintance. Peak Performance, 164, p. 8-11.
  3. Medicine and Science in Sports and Exercise, 34 (1), p. 92-97

Page Reference

If you quote information from this page in your work, then the reference for this page is:

  • MACKENZIE, B. (2003) Fat Burning Zone [WWW] Available from: [Accessed