http://www.nutritionj.com/content/3/1/9

Abstract

The principle of "a calorie is a calorie," that weight change
in hypocaloric diets is independent of macronutrient
composition, is widely held in the popular and technical
literature, and is frequently justified by appeal to the laws
of thermodynamics. We review here some aspects of
thermodynamics that bear on weight loss and the effect of
macronutrient composition. The focus is the so-called
metabolic advantage in low-carbohydrate diets - greater weight
loss compared to isocaloric diets of different composition.
Two laws of thermodynamics are relevant to the systems
considered in nutrition and, whereas the first law is a
conservation (of energy) law, the second is a dissipation law:
something (negative entropy) is lost and therefore balance is
not to be expected in diet interventions. Here, we propose
that a misunderstanding of the second law accounts for the
controversy about the role of macronutrient effect on weight
loss and we review some aspects of elementary thermodynamics.
We use data in the literature to show that thermogenesis is
sufficient to predict metabolic advantage. Whereas homeostasis
ensures balance under many conditions, as a general principle,
"a calorie is a calorie" violates the second law of
thermodynamics.

**********

TC

In article
<1117558535.260392.74070~z14g2000cwz.googlegroups.com>, "TC"
<tunderbar~hotmail.com> wrote:

  > http://www.nutritionj.com/content/3/1/9
  >
  > Abstract
  >
  > The principle of "a calorie is a calorie," that weight
  > change in hypocaloric diets is independent of macronutrient
  > composition, is widely held in the popular and technical
  > literature, and is frequently justified by appeal to the
  > laws of thermodynamics. We review here some aspects of
  > thermodynamics that bear on weight loss and the effect of
  > macronutrient composition. The focus is the so-called
  > metabolic advantage in low-carbohydrate diets - greater
  > weight loss compared to isocaloric diets of different
  > composition. Two laws of thermodynamics are relevant to the
  > systems considered in nutrition and, whereas the first law
  > is a conservation (of energy) law, the second is a
  > dissipation law: something (negative entropy) is lost and
  > therefore balance is not to be expected in diet
  > interventions. Here, we propose that a misunderstanding of
  > the second law accounts for the controversy about the role
  > of macronutrient effect on weight loss and we review some
  > aspects of elementary thermodynamics. We use data in the
  > literature to show that thermogenesis is sufficient to
  > predict metabolic advantage. Whereas homeostasis ensures
  > balance under many conditions, as a general principle, "a
  > calorie is a calorie" violates the second law of
  > thermodynamics.
  >
  > **********
  >
  > TC
  >

"A calorie is a calorie" is a crock and everyone knows it. It
violates no thermodynamic laws.......

Sugar/starch is easier for the body to convert to glucose
which is the primary fuel for the body to make ATP, the end
source for actual energy.

The body has to work a damn site harder to convert protein to
glucose. The pathways are longer and burn more calories for
the final conversion.

It does not take a rocket scientist to figure out that low
carbing is not efficient, hence total protein calories to ATP
are not going to be as great as sugar/starch calories to ATP.

Duh.

I still have not figured out or been able to find how and why
fat burn is so inefficient, and why fat fasting/consuming all
or mostly fat works the fastest of all to burn body fat... I
just know it works. It sux but it functions as advertised.

I still have a lot of learning to do. ;-)
--
Om.

"My mother never saw the irony in calling me a
son-of-a-bitch." -Jack Nicholson

You're thinking on the cellular level, but there's also the
physiological level. It's been known by farmers for decades
that soy and corn fattens animals while coconut oil makes them
lean. Too much lipid peroxidation from unsaturated fatty acids
will suppress metabolism, due to effects on the thyroid. I'm
sure you've heard the phrase "corn fed." You can do a google
search for ray peat newsletter and read some of this from
biochemist Ray Peat's free essays.

OmManiPadmeOmelet wrote:
  > "A calorie is a calorie" is a crock and everyone knows it.
  > It violates no thermodynamic laws.......
  >
  > Sugar/starch is easier for the body to convert to glucose
  > which is the primary fuel for the body to make ATP, the end
  > source for actual energy.

Actually in terms of molecules used, fatty acids are the
primary source of ATP for the body (for the brain it's
glucose).

  > The body has to work a damn site harder to convert protein
  > to glucose. The pathways are longer and burn more calories
  > for the final conversion.
  >
  > It does not take a rocket scientist to figure out that
  > low carbing is not efficient, hence total protein
  > calories to ATP are not going to be as great as
  > sugar/starch calories to ATP.
  >
  > Duh.
  >
  > I still have not figured out or been able to find how and
  > why fat burn is so inefficient,

In what way is it inefficient? The reason it's used as an
energy store by the body is that because it has more energy
per gram than glucose.

  > and why fat fasting/consuming all or mostly fat works the
  > fastest of all to burn body fat... I just know it works. It
  > sux but it functions as advertised.

If you assume more fat = less glucose, then you also have less
insulin. Insulin switches off fat burning, so the lower the
insulin is the higher fat burning will be.

MattLB