First, a few words about chemistry, even if this means returning briefly to the
dismal surroundings of the chemistry classroom. One gram of body fat has
seven kilo-calories of potential chemical energy, or seven "calories" for short.
In comparison, one gram of glucose has only four calories. Energy, whether from fat or
glucose, is released for use when the molecules are subdivided into their individual
components. To put it another way, energy is released when^high-energy molecular
compounds are broken down into their low-energy building blocks. This is exactlywhat
happens in the power plants - with the help of oxygen. Now you know where the energy
to run comes from.
Let's take a look at the compounds of glucose and a special fatty acid called
palmitic acid. Glucose is C8H12O8; palmitic acid C15H31COOH. To be honest,
these formulas mean absolutely nothing to me, and since you too may have trouble
interpreting the full meaning of these hieroglyphs, we'll do something that was strictly
forbidden at school. We'll delete everything that looks hostile and confusing, namely all those
subscript digits and duplicate letters. What we wind up with is clear and straight forward:
C, H, O - carbon, hydrogen, oxygen. These three substances form the fuel that gives our
body its strength.
As you can see, it turns out that our two main energy suppliers - fat and glucose -
have identical components. Both are made up of C, H, and O. They differ only in the
structure of the nutrient molecules released from food during digestion. It's worth noting
that, in principal, it doesn't matter to your body in the slightest whether its energy comes
from fat or glucose.
I can well imagine what some of you are thinking. You want to know whether
running tends to burn off fat, or whether the power plants prefer glucose, making
it harder for you to lose weight. To answer this question, we must step back and look
at the larger picture. Fats cannot be burned inour metabolism without oxygen. Glucose,
on the other hand, can. As long as there is enough oxygen in the incinerators, the power
plants will prefer fatty acids, which they normally take from the bloodstream. There is good
reason for their preference for fat over glucose. Our muscle cells are not dumb. They know
that if there is a sudden upsurge in energy requirements, e.g. to run at high speed, their
power plants will not have enough oxygen on supply because the runner, if he or she runs
too fast, will soon be out of breath. Once the oxygen supply is cut off, the only thing the cell
can burn is glucose. And because the cell also knows that the supply of glucose in the glycogen
stores is limited, it will save these reserves for a possible "red alert": anaerobic consumption.
Perhaps you've heard already that marathon runners and triathlon specialists tend
to gorge themselves on spaghetti the day before a competition. They do so because
they need to fill their glycogen stores to the brim if they want enough energy reserves
for their many little "red alerts." These athletes are always straddling the border between
aerobic and anaerobic consumption, and always cross it for short periods of time. Being a novice,
you will spend most of your time on the wrong side of this border, and will often switch to"red alert."
Before long, your glycogen stores will be plundered - and the fat cells spared. A brisk walk would
leave enough oxygen at your disposal so that your body would only consume fats. The problem is
that a brisk walk doesn't require much energy from your muscles, so it's useless as a means of
reducing body weight. Your organism is familiar with the load placed on it by a briskwalk. What
it doesn't know is the higher load caused by a slow run.
Not until your organism has adapted to this load, so that jogging poses no more difficulties
than a brisk walk, will you be able to burn off more and more fat. Now, at last, you can begin
to tap your fat deposits. In other words,it can't simply be taken for granted that you gain energy by
burning fattyacids. Yet another adaptation is required, and it can't be expected to occurin your first
few days of jogging. Those who think that a couple of days of running will suffice for a visible loss of
body weight are fooling themselves. It's a biological impossibility.
If weight reduction is your second major target in running, you should take a long, hard look
at this next sentence: "If, and only if, I run regularly, I will train the ability of my muscle cells to prefer
fats as fuel." A bit convoluted, perhaps, but worth committing to memory.