The "fat-burning zone" is one of the many misconceptions that
seem to be passed from one exerciser to another. The explanation
for the myth is a combination of misinterpreted biochemistry and
exercise physiology, inadequate education of many workers in the
fitness industry, and a magazine culture that often favors
sensationalism over scientific fact.
Let's start with a brief explanation of where this belief comes
from.
Our body uses a mix of fat and carbohydrate to fuel the energy
needs of our cells. Researchers can quantify this mix with high
accuracy in an exercise physiology laboratory using expired gas
analysis. The percent contribution of fat and carbohydrate does
indeed vary depending on the intensity of exercise.
For instance, when we transition from rest to exercise, there is an
increase in energy expenditure (i.e., calories burned) to meet the
increased needs of our muscles. When the exercise is of a low
intensity, our bodies preferentially use fat as a fuel, similar to
a resting state. Thus, low intensity exercise does predominantly
rely on fat to fuel contracting muscles................
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