You generally lose more weight on high protein diets.  Although protein
contains about 4 calories/g about one third of that energy actually
gets used to convert the other two thirds to accessible energy for the
body.

The protein you eat is broken down to amino acids in the digestive
track.  In order to use these amino acids as energy your body has to
either directly oxidize them, or first convert them to glucose by
gluconeogenesis in the liver to make them available as energy for the
rest of the body.  Converting amino acids to glucose costs energy and
the energy gained from directly oxidizing amino acids in the liver is
used to fuel this convertion of amino acids to glucose.  The net effect
is that only about two thirds of the energy remains available as a fuel
source for the body.  See the abstract below for details.

Physiol Rev. 1992 Apr;72(2):419-48.

Quantitative analysis of amino acid oxidation and related
gluconeogenesis in
humans.

Jungas RL, Halperin ML, Brosnan JT.

Department of Physiology, University of Connecticut Health Center,
Farmington.

Significant gaps remain in our knowledge of the pathways of amino acid
catabolism in humans. Further quantitative data describing amino acid
metabolism
in the kidney are especially needed as are further details concerning
the
pathways utilized for certain amino acids in liver. Sufficient data do
exist to
allow a broad picture of the overall process of amino acid oxidation to
be
developed along with approximate quantitative assessments of the role
played by
liver, muscle, kidney, and small intestine. Our analysis indicates that
amino
acids are the major fuel of liver, i.e., their oxidative conversion to
glucose
accounts for about one-half of the daily oxygen consumption of the
liver, and no
other fuel contributes nearly so importantly. The daily supply of amino
acids
provided in the diet cannot be totally oxidized to CO2 in the liver
because such
a process would provide far more ATP than the liver could utilize.
Instead, most
amino acids are oxidatively converted to glucose. This results in an
overall ATP
production during amino acid oxidation very nearly equal to the ATP
required to
convert amino acid carbon to glucose. Thus gluconeogenesis occurs
without either
a need for ATP from other fuels or an excessive ATP production that
could limit
the maximal rate of the process. The net effect of the oxidation of
amino acids
to glucose in the liver is to make nearly two-thirds of the total
energy
available from the oxidation of amino acids accessible to peripheral
tissues,
without necessitating that peripheral tissues synthesize the complex
array of
enzymes needed to support direct amino acid oxidation. As a balanced
mixture of
amino acids is oxidized in the liver, nearly all carbon from glucogenic
amino
acids flows into the mitochondrial aspartate pool and is actively
transported
out of the mitochondria via the aspartate-glutamate antiport linked to
proton
entry. In the cytoplasm the aspartate is converted to fumarate
utilizing urea
cycle enzymes; the fumarate flows via oxaloacetate to PEP and on to
glucose.
Thus carbon flow through the urea cycle is normally interlinked with
gluconeogenic carbon flow because these metabolic pathways share a
common step.
Liver mitochondria experience a severe nonvolatile acid load during
amino acid
oxidation. It is suggested that this acid load is alleviated mainly by
the
respiratory chain proton pump in a form of uncoupled
respiration.(ABSTRACT
TRUNCATED AT 400 WORDS)

Publication Types:
   Review
   Review, Tutorial

PMID: 1557428 [PubMed - indexed for MEDLINE]

Its not necessarily the protein in the yogurt (its really higher in
carbs with minimal protein), and its not the flora either, altho both
can be good reasons to eat yogurt.  New studies show that foods that
contain CALCIUM are important in losing bodyfat. Something in the
digestive enzymes of calcium rich foods helps the body to breakdown
stored bodyfat. Just when the dairy farmers were about to go bankrupt:
http://my.webmd.com/content/article/23/1728_56703

<<joni>>

---------------------------------

*If we could give every individual the right amount of nourishment and
exercise, not too little and not too much, we would have found the
safest way to health.*- Hippocrates c. 460 - 377 B.C.