-==Q: No such thing as Glycogen!!!?==-
minerva007 at usa.net
Sun Oct 24 19:14:05 EST 1999
That got your attention! Actually, the question is more complicated than
I know there must be some very smart people in here so if you can help
me out with my confusion I'd be eternally grateful.
I also apologise if this is the wrong group to post to, I can't seem to
find a better one in english!
A while back I spoke to a person on the Internet who told me that much of
the research into metabolism was wrong! I don't know what happened but I
cannot get in touch with him any more. He promised to send me references on
this matter. But that was all a while ago. So now I come to you kind people
for my answers ;)
He told me that there has been a lot of research on metabolism, although
you will not
find it without searching, probably due to the influence of the powerful
He said FAT is the only fuel used by human muscles for contraction! And
that intense exercise does not cause any change in blood glucose levels due
to this fact! In fact, the only thing that will change glucose levels is
the action of the hormone insulin. The glycogen in the muscle is used ONLY
for emergency and is NOT used for fuel in the muscles at all be they
anaerobic or aerobic processes!
That's right the mechanism of fatty-acid fuelled conversion of ADP to ATP
(ADP of course is produced by muscle contraction) is exactly the same
whether the body is in anaerobic or aerobic metabolism, only during aerobic
activity levels the low level activity can be sustained longer due to
oxygen availability. In anaerobic activity bursts there is an oxygen
deficit which limits such activity to relatively short intervals. This is
due much to a build up in the tissues of incompletely oxidised waste
products. Also the brain needs large amounts of oxygen and can not tolerate
a reduction for long.
Muscular contractions are fuelled solely by free fatty acids in a protein
complex (acetylcarnitine), which is the energy source for the translation
of the adenosine diphosphate back to triphosphate. The enzymes used in the
muscles do not originate there either but come mainly from the liver.
Only.01% of muscle mass is glycogen and no glucose is stored in any tissue
except the liver! In fact, the body (other than the brain and a few other
cellularly dense tissues) CANNOT use or "burn" carbohydrates (glycogen or
glucose) as an energy source at all.
All glycogen is stored in the liver (which can hold a maximum of 1/2 pounds
of glycogen). This fuels the brain and other cells but NOT the muscles. In
fact, even body heat production will only use fat as a fuel.
Heavy stuff huh
Well, I explained to him about the metabolic pathways that I had read in a
sports textbook (ie. The Lactic Acid pathway (Glycolysis); the Alactate
System and the Citric Acid or Krebs Cycles). But again he reiterated that
the only mechanism that exists for muscle contraction is fatty
acid-acetyl-carnitine complexes used as energy to replace ATP. Glucose is
only consumed in the body either by conversion to fatty acids or as a
low-level fuel in the brain. These other bodily functions are where these
other cycles are used and some such as the krebs cycle are mainly
mechanisms in which glucose is converted into fat.
He promised many references, but again, I was soon after that when I lost
touch with him ;(.
He also sighted a study in which rats were fed either on a zero-carb high
fat diet or a normal high-carb diet. In theory, if glycogen were the fuel
for muscles than the rats on the carb diet would last longer in exercise
bouts than those with equal calories of fat. Actually, the normal-diet rats
lasted only 3 hours swimming, while the experiment had to be terminated
when the fat-fed rats were still swimming after 8 hours.
He mentioned that high levels of carbohydrates are much of the reason
people are suffering from obesity. This is basically what Dr Atkins says
also (ie. The book the diet revolution). The carbohydrates and sugars in
our diets are converted to fat without limit. The body releases insulin to
force the adipose cells to convert any excess glucose into fat. Dr Atkin's
and the idea of foods glycemic index suggests that an overdose of insulin
(carb foods) takes out too much glucose from your bloodstream and leaves
you hungry for more, causing obesity and diabetes. In fact diabetes is an
unnatural disease which is found ONLY in humans and their carnivorous pets
fed on high carb foods 30 to 40% of humans have some form of it.
Finally, he said that there is a natural mechanism which will make you
unable to ingest more fat than you can absorb and use (ie. You will feel
unable to eat any more). He says that no such thing exist for high
carbohydrate diets. He mentioned that in the arctic there have been reports
of people eating as much as 10,000 calories while almost sedentary and not
gaining an ounce!! Another researcher (who supposedly published in
Scientific American (Dec 1959)). He used radioactive tracers to mark
digested fat molecules but they did not wind up in adipose tissue. However,
the radioactively marked glucose molecules did end up as fat.
That's about it
has anyone else ever read anything like this before?? Is it
totally false? Or was this kind of thing once believed to be so, but now
has disproved? Have any experiments been done like this before?? Do the
metabolic pathways actually work like this?
Many questions, I know, but I would appreciate any help you can give me.
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