Efficient Fat Burning
 

What does it mean, exactly, when the body is said to become more
efficient at burning fat?

Does it mean that the body burns more fat or less fat?

"Efficient" could mean "less fat" in the same way that fuel efficiency
in cars means *less* fuel used for the same distance. Thus, the more
"efficient" our bodies become at using fat, the more intense our
workouts have to be to burn the same amount as before!

But that's semantics...what's the actual physiology??

Efficient Fat Burning
 

On Jan 21, 11:54*pm, Prisoner at War
wrote:
What does it mean, exactly, when the body is said to become more
efficient at burning fat?

Does it mean that the body burns more fat or less fat?

"Efficient" could mean "less fat" in the same way that fuel efficiency
in cars means *less* fuel used for the same distance. *Thus, the more
"efficient" our bodies become at using fat, the more intense our
workouts have to be to burn the same amount as before!

But that's semantics...what's the actual physiology??

Yes.

Efficient Fat Burning
 

"Prisoner at War" wrote in message
...

What does it mean, exactly, when the body is said to become more
efficient at burning fat?

Does it mean that the body burns more fat or less fat?

"Efficient" could mean "less fat" in the same way that fuel efficiency
in cars means *less* fuel used for the same distance. Thus, the more
"efficient" our bodies become at using fat, the more intense our
workouts have to be to burn the same amount as before!

But that's semantics...what's the actual physiology??

For the physiology, I think Gary Taubes' "Good Calories, Bad Calories" may
help.

The phrase seems ambiguous to me, thus, might need contextual clarification.

Efficient Fat Burning
 

On Jan 22, 11:36 am, "Cubit" wrote:


For the physiology, I think Gary Taubes' "Good Calories, Bad Calories" may
help.

The phrase seems ambiguous to me, thus, might need contextual clarification.

Indeed! But it's such a popular sentiment, and when I just read it
again in "Runner's World Complete Book of Running" I just had to ask
and find out, once and for all...the usual context appears to suggest
that our bodies burn more fat as it becomes more "efficient," though
I've also read somewhere (Noakes?) that being more efficient means
that less calories are burned for the same work....

Efficient Fat Burning
 

"Prisoner at War" wrote in message
...

What does it mean, exactly, when the body is said to become more
efficient at burning fat?

Does it mean that the body burns more fat or less fat?

Without context, it's difficult to know, but it seems a poor choice of
wording.

During aerobic exercise, it is *more* efficient to burn *more* fat because
that means that you're burning less glycogen, and glycogen is much more
scarce than fat (you only have ~400gm of it and that only provides as much
energy as about 200gm fat)

This is fairly basic stuff -- any book on exercise physiology or endurance
training will discuss it.

Cheers,
--
Elflord

Efficient Fat Burning
 

On Jan 21, 8:54*pm, Prisoner at War wrote:
What does it mean, exactly, when the body is said to become more
efficient at burning fat?

Efficiency refers to how high a yield of some desired output we obtain
relative to some costly inputs to some process. There is always some
frame of reference defined by human values which determine what
efficiency means in that context.

E.g. the efficiency of a computer program is how much calculation it
gets done in a given amount of time. Time is a costly input to the
process, the result is the deisred output. The energy efficiency of
computation is important: we want CPU's to use less electricity, while
still running fast.

The efficiency of an engine is how much work you obtain from the
energy source, such as fuel. The energy that doesn't become work is
wasted as heat.

Heating can be efficient also. Heating a poorly insulated home is less
efficient than heating an insulated one. Maintaining the place at a
given temperature (the benefit) requires more input (energy) if heat
escapes easily. When heat is easily available (basically, is already
the waste from another process), you don't care about heat efficiency.
A big engine can easily heat the interior of a car, even if the car is
poorly insulated. The heat is produced even if you don't use it for
heating, so wasting it doesn't matter.

To be more efficient at burning fat, it means that the body gets rid
of fat (the desired effect of the process) with less effort (the
costly input). Effort consists of diet and exercise.

So the claim that a body is more efficient at burning fat means that
it can shed body fat with less exercise and less dieting effort than
an inefficient body.

But that's semantics...what's the actual physiology??

The actual physiology is fat mobilization. The difficulty in losing
fat isn't actually burning it, but getting it to march out of the fat
cells and into circulation.

Think about it; you could easily consume a pound of butter over the
next week, without putting any of it on as fat. You could not with
equal ease get a pound of fat to leave your adipose tissue,
particularly if you're already lean. But if you could mobilize a pound
of fat, it would be as easily burned off as that pound of butter.

Efficient Fat Burning
 

Dnia 2008-01-22 Elflord napisa³(a):
"Prisoner at War" wrote in message
...

What does it mean, exactly, when the body is said to become more
efficient at burning fat?

Does it mean that the body burns more fat or less fat?

Without context, it's difficult to know, but it seems a poor choice of
wording.

During aerobic exercise, it is *more* efficient to burn *more* fat because
that means that you're burning less glycogen, and glycogen is much more
scarce than fat (you only have ~400gm of it and that only provides as much
energy as about 200gm fat)

That would be liver alone, AFAIR. Most of glycogen is stored in muscles
and it takes a while to burn it all. I remember reading about glycogen
depletion workouts (recent fad in some sport related training regimes)
and it took quite an effort to burn it all, plus some fasting too.

Fat isn't good fuel source for aerobic workouts, because it needs more
oxygen to use it. IOW you get winded more easily and overall intensity
must go down (a lot).

This is fairly basic stuff -- any book on exercise physiology or endurance
training will discuss it.

I'm missing context too, so it could be that I write about unrelated
topic. Anyway, we have more than 400mg of glycogen and fat is bad fuel
for intense aerobic activity. Your body will use it, if it has no
choice, but your training will be lousy.

--
Andrzej Rosa 1127R

Efficient Fat Burning
 

On 2008-01-22, Andrzej Rosa wrote:

During aerobic exercise, it is *more* efficient to burn *more* fat because
that means that you're burning less glycogen, and glycogen is much more
scarce than fat (you only have ~400gm of it and that only provides as much
energy as about 200gm fat)

That would be liver alone, AFAIR. Most of glycogen is stored in muscles
and it takes a while to burn it all.

I don't think so. We enough to cover about 2hrs of hard running -- that's
a bit over 2000 calories. That's where the "hitting the wall" theory came
from -- you don't have enough glycogen to run a marathon without using some
fat.

I remember reading about glycogen
depletion workouts (recent fad in some sport related training regimes)
and it took quite an effort to burn it all, plus some fasting too.

Fat isn't good fuel source for aerobic workouts, because it needs more
oxygen to use it.

Without qualification, it's hard to say whether it's a "good" fuel source for
aerobic workouts.

It's "good" in the sense that it's abundant, but "bad" in the sense that it
doesn't provide energy as quickly.

Any kind of speed work depends heavily on glycogen stores, because intensity
is key.

But at least for longer events (e.g. 2hrs+), it is advantageous to be able to
metabolise fat as quickly as possible, because fat is abundant whereas glycogen
is not.

IOW you get winded more easily and overall intensity
must go down (a lot).

This is fairly basic stuff -- any book on exercise physiology or endurance
training will discuss it.

I'm missing context too, so it could be that I write about unrelated
topic. Anyway, we have more than 400mg of glycogen and fat is bad fuel
for intense aerobic activity. Your body will use it, if it has no

If you're doing the exercise for any purpose besides competing in endurance
events, I'd agree.

People competing in endurance events can and should do base training to address
this.

Cheers,
--
Elflord

Efficient Fat Burning
 

On Jan 22, 12:02*pm, Elflord wrote:
"Prisoner at War" wrote in message
...

What does it mean, exactly, when the body is said to become more
efficient at burning fat?

Does it mean that the body burns more fat or less fat?

Without context, it's difficult to know, but it seems a poor choice of
wording.

During aerobic exercise, it is *more* efficient to burn *more* fat because
that means that you're burning less glycogen, and glycogen is much more
scarce than fat (you only have ~400gm of it and that only provides as much
energy as about 200gm fat)

That's different. The desired result during this type of sport is (for
instance) to go the farthest in the least amount of time, not to lose
the most adipose fat with the least effort.

You can't discuss the efficiency of a process without knowing what the
important result that that process must yield, and what input
resources are to be optimized.

Efficient Fat Burning
 

Dnia 2008-01-22 Elflord napisa³(a):
On 2008-01-22, Andrzej Rosa wrote:

That would be liver alone, AFAIR. Most of glycogen is stored in muscles
and it takes a while to burn it all.

I don't think so. We enough to cover about 2hrs of hard running -- that's
a bit over 2000 calories. That's where the "hitting the wall" theory came
from -- you don't have enough glycogen to run a marathon without using some
fat.

That 2 hours of hard running rings true, so it may be that I mixed the
numbers (that is miligrams with calories).

[...]
I'm missing context too, so it could be that I write about unrelated
topic. Anyway, we have more than 400mg of glycogen and fat is bad fuel
for intense aerobic activity. Your body will use it, if it has no

If you're doing the exercise for any purpose besides competing in endurance
events, I'd agree.

And endurance events, which take more than 2000 cal to finish. Most of
them is way shorter. Even ten miles run should be safely within the
limits of our glycogen stores.

[...]
--
Andrzej Rosa 1127R