From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med.nutrition
Subject: Re: Atkins diet
Date: 14 Apr 1998 21:29:17 GMT

In <35336333.DD2C76A3@newbridge.com> Paul Chefurka
<pchefurk@newbridge.com> writes:

>This is strange.  I was always of the understanding that the brain
>and heart use ketones preferentially to glucose for fuel (if they
>are available).  The rationale is that these two organs must keep
>functioning, no matter what fuel sources are available, and that
>glucose derived from protein (either dietary or endogenous) via
>gluconeogenesis is a used only when glycogen has been exhausted and
>there is insufficient fat to metabolize for ketones - because
>gluconeogenesis is a poorer source of energy than either of the
>other two mechanisms.
>
>Now, I don't have a degree in biochem or nutrition, but this view
>does seem reasonable to me, given that the body is such a remarkably
>clever adaptive machine.  It seems unlikely that the human body
>would have developed over millions of years on a single-fuel strategy.
>This is especially apparent when you consider the environmental
>variations we can survive - from carbohydrate-rich sub-tropical
>climates to carbohydrate-poor arctic and sub-arctic regions.
>
>The other thing to consider is that, during our hunter-gatherer
>period, there would of necessity have been long periods (several
>months per year) during which carbohydrates were relatively or
>completely unavailable (i.e. during winters in temperate regions).
>It is unlikely that, in the absence of dietary carbohydrates for
>several months, our brains, hearts and other muscles simply stopped
>functioning for lack of fuel.  Natural selection would have weeded
>out any population with such a shortcoming right quick.
>
>All this is supported by the experience of hundreds of thousands
>of low-carbohydrate dieters, who typically report greater mental
>acuity and reasonably low levels of loss of lean muscle during
>extended low-carb diets.  Personally, I've been on a low-carb
>diet for 3 months now.  My intake has been, on average, less than
>50g/day for that period.  This is less than 200 kCal/day from
>carbohydrates.  During that time, my mental ability has improved,
>my weight has gone down 20%, my BP has dropped from 155/110 to
>125/80, my triglycerides have gone down 40%, my cholesterol has
>remained stable and my aerobic ability has increased.  This is
>hardly a picture of clinical pathology.



Comment:  The heart works only on ketones from fats, and can't run on
glucose.  But that's okay, because you always have some fat around (and
when you've burned ALL your fat, including that around your organs, you
die).  The normal brain works something like 99% on glucose, but during
prolonged fasting can switch over about 50% to ketones.  The object
here is to conserve sugar use, since sugar in fasting can only be made
from protein (muscle).  The brain can't entirely switch over, as
evidenced by the fact that if your blood glucose drops to zero, you
will lose consciousness and die, no matter how long you've been
fasting.

                               Steve Harris, M.D.

From: sbharris@ix.netcom.com(Steven B. Harris)
Newsgroups: sci.med.nutrition
Subject: Re: Atkins diet
Date: 14 Apr 1998 21:33:29 GMT

In <3533B3FE.6233@oitunix.oit.umass.edu> Adam Fahy
<afahy@oitunix.oit.umass.edu> writes:

>no spam wrote:
>
>> No diet, no matter how
>> strict in caloric intake or in "variety" intake will cause any significant
>> muscle loss.  The only thing that will cause muscle loss is lack of
>> exercise.
>
>This is very incorrect.


   Yep.  Who is this guy trying to kid?  Short yourself on any one of
the 8 amino acids you need, and you lose muscle.  Fail to eat enough
carbohydrate to burn the fat calories and run the brain cells you need
to stay alive (about 100 grams a day), and you'll lose muscle to make
that carbohydrate.

From: "Steve Harris" <sbharris@ix.netcom.com>
Newsgroups: sci.med.nutrition
Subject: Re: sugar addictions
Date: Wed, 15 Aug 2001 21:43:15 -0700

mnt wrote in message <78xe7.6102$sr4.2286941@news1.elmhst1.il.home.com>...
>it's not a question of just saying no to sugar,  the brain demands sugar for
>several reasons, take the case of an overactive mind,  it demands fuel at a
>rate faser than the body can provide,  in this case,  halting sugar intake
>will cause a breakdown and burnout,

COMMENT


That's ridiculous. Whether you're using your mind at full speed or are fast
asleep, the difference in glucose use isn't more than 10%. Almost all (not
quite all, but almost all ) the calories used by your brain are just in upkeep
and operating costs, and have nothing to do with what the mind is doing.
It's very much the same as with the computer on your desk, which uses
almost the same power when it's working hard as when it's just sitting
there turned on but doing nothing. The differences you see in a PET
scan are enhanced like the mountains on a world-globe. A real globe
with moutains to scale would be smoother than a billiard ball, and that's
not much fun.


>so you have to first slow down the mind to halt sugar cravings,  again it's
>is not a question of just saying no because there are five sections in the
>brain and each of them competes for fuel,  the area known as the limbic
>system always wins and it is not capable of saying "no".
>
>sounds like you have been brainwashed by that idiot John "the man"



Would an idiot be a person who doesn't know what they are talking about,
but talks anyway?

SBH

From: "Steve Harris" <SBHarris123@ix.netcom.com>
Newsgroups: sci.med.nutrition
Subject: Re: Is it possible to have too little sugar in your diet?
Date: Fri, 11 May 2001 15:18:27 -0600

 "TecAddict" <tecaddict@MyRealBoxDELETE.com> wrote in message
 news:9dh5gk$n8q$1@bob.news.rcn.net...
 > Brain doesn't require glucose. Nervous system mainly. But not much.


 Sorry, but you don't know what you're talking about. Even after prolonged
 starvation to adapt the brain, it still requires 50% of its calories as
 glucose. That's around 100 kcal a day or 28 grams of glucose a day. Optimal
 protein sparing during fasting occurs at around 100 g glucose intake a day.
(obviously this is not a complete fast, but a modified fast in which protein
and carbohydrate are both given in amounts suitable to maximally decrease
muscle catabolism).

SBH

From: "Steve Harris" <SBHarris123@ix.netcom.com>
Newsgroups: sci.med.nutrition
Subject: Re: Is it possible to have too little sugar in your diet?
Date: Sat, 12 May 2001 02:00:19 -0600

"Alf Christophersen" <alf.christophersen@basalmed.uio.no> wrote in message
news:3afc866f.30724240@nntp.uio.no...
> On Fri, 11 May 2001 15:18:27 -0600, "Steve Harris"
> <SBHarris123@ix.netcom.com> wrote:
>
> > Sorry, but you don't know what you're talking about. Even after
> > prolonged starvation to adapt the brain, it still requires 50% of its
> > calories as glucose. That's around 100 kcal a day or 28 grams of
> > glucose a day. Optimal protein sparing during fasting occurs at around
> > 100 g glucose intake a day. (obviously this is not a complete fast,
> > but a modified fast in which protein and carbohydrate are both given
> > in amounts suitable to maximally decrease muscle catabolism).
>
> Only valid when all fats are gone.

What is? All fats are never gone in your body. You're dead long before.

From: "Steve Harris" <SBHarris123@ix.netcom.com>
Newsgroups: sci.med.nutrition
Subject: Re: Is it possible to have too little sugar in your diet?
Date: Fri, 11 May 2001 18:10:05 -0600

"TecAddict" <tecaddict@MyRealBoxDELETE.com> wrote in message
news:9dhkoa$1nl$1@bob.news.rcn.net...
> nope, good guess though
..
COMMENT:.
..
..Oh, it wasn't a guess. This is what the studies show. Now, if you have
studies which find a different result, I want you to post them.

Am J Physiol 1989 Jun;256(6 Pt 1):E805-10

Generalized decrease in brain glucose metabolism during fasting in humans
studied by PET.

Redies C, Hoffer LJ, Beil C, Marliss EB, Evans AC, Lariviere F, Marrett
S, Meyer E, Diksic M, Gjedde A, et al

McConnell Brain Imaging Unit, Montreal Neurological Institute, Quebec,
Canada.

In prolonged fasting, the brain derives a large portion of its oxidative
energy from the ketone bodies, beta-hydroxybutyrate and acetoacetate,
thereby reducing whole body glucose consumption. Energy substrate
utilization differs regionally in the brain of fasting rat, but
comparable information has hitherto been unavailable in humans. We used
positron emission tomography (PET) to study regional brain glucose and
oxygen metabolism, blood flow, and blood volume in four obese subjects
before and after a 3-wk total fast. Whole brain glucose utilization fell
to 54% of control (postabsorptive) values (P less than 0.002). The whole
brain rate constant for glucose tracer phosphorylation fell to 51% of
control values (P less than 0.002). Both parameters decreased uniformly
throughout the brain. The 2-fluoro-2-deoxy-D-glucose lumped constant
decreased from a control value of 0.57 to 0.43 (P less than 0.01).
Regional blood-brain barrier transfer coefficients for glucose tracer,
regional oxygen utilization, blood flow, and blood volume were unchanged.

PMID: 2786677



> "Steve Harris" <SBHarris123@ix.netcom.com> wrote in message
> news:9dhk8e$roa$1@slb6.atl.mindspring.net...
> > "TecAddict" <tecaddict@MyRealBoxDELETE.com> wrote in message
> > news:9dh5gk$n8q$1@bob.news.rcn.net...
> > > Brain doesn't require glucose. Nervous system mainly. But not much.
> >
> >
> > Sorry, but you don't know what you're talking about. Even after
> > prolonged starvation to adapt the brain, it still requires 50% of its
> > calories as glucose. That's around 100 kcal a day or 28 grams of
> > glucose a day. Optimal protein sparing during fasting occurs at around
> > 100 g glucose intake a day.