Hi Olafur, Doug;
I don't see why the high protein diet increased satiety
unless there something else going on beside the increased
energy expenditure during processing by the liver.
I suspect that the protein is also correcting sub-clinical
deficiencies in various amino-acids (essential and
non-essential).
Cheers,
Michael C Price
----------------------------------------
http://mcp.longevity-report.com
http://www.hedweb.com/manworld.htm
"Olafur Pall Olafsson" wrote in message
ups.com...
Hi Michael and Doug,
The weight reduction effects of high protein diets might be largely
caused by increased metabolism in the liver as the abstract below
shows. Increasing the metabolism in the liver might not be very
healthy for you. The prefered method of course would be to simply eat
fewer calories.
Physiol Rev. 1992 Apr;72(2):419-48. Related Articles, Links
Click here to read
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]
Michael C Price wrote:
Here they are with authors and PMIDs
(plus a review article)
Curr Opin Clin Nutr Metab Care. 2003 Nov;6(6):635-8.
The significance of protein in food intake and body weight regulation.
Westerterp-Plantenga MS.
Department of Human Biology, PO Box 616, 6200 MD Maastricht, The
Netherlands.
PURPOSE OF REVIEW: To highlight the underexposed but important role of
protein in food intake and body weight regulation. RECENT FINDINGS:
Protein
plays a key role in food intake regulation through satiety related to
diet-induced thermogenesis. Protein also plays a key role in body weight
regulation through its effect on thermogenesis and body composition. A
high
percentage of energy from dietary protein limits body weight (re)gain
through its satiety and energy inefficiency related to the change in
body
composition. SUMMARY: Protein is more satiating than carbohydrate and
fat in
the short term, over 24 h and in the long term. Thermogenesis plays a
role
in this satiety effect, but the role of satiety hormones still needs to
be
elucidated. On the short-term 'fast' proteins are more satiating than
'slow'
proteins, and animal protein induces a higher thermogenesis than
vegetable
protein. In the longer term the higher postabsorptive satiety and
thermogenesis are sustained irrespective of the protein source.
High-protein
diets affect body weight loss positively only under ad-libitum energy
intake
conditions, implying also a decreased energy intake. Body composition
and
metabolic profile are improved. Additional protein consumption results
in a
significantly lower body weight regain after weight loss, due to body
composition, satiety, thermogenesis, and energy inefficiency, while the
metabolic profile improves. Implications from these findings a for
practice, recommendations for increasing the percentage of energy from
protein while reducing energy intake; for clinical research, assessment
of
the paradox of increasing the percentage energy from a highly satiating
macronutrient; of the potential roles of protein in a negative and
positive
energy balance; assessment of possibilities of replacing dietary protein
by
effective amino acids or peptides that may show a similar impact on body
weight regulation.
Publication Types:
Review
Review, Tutorial
PMID: 14557793
Br J Nutr. 2005 Feb;93(2):281-9.
Additional protein intake limits weight regain after weight loss in
humans.
Lejeune MP, Kovacs EM, Westerterp-Plantenga MS.
Department of Human Biology, Maastricht University, P.O. Box 616, 6200
MD
Maastricht, The Netherlands.
Since long-term weight maintenance (WM) is a major problem,
interventions to
improve WM are needed. The aim of the study was to investigate whether
the
addition of protein to the diet might limit weight regain after a weight
loss of 5-10 % in overweight subjects. In a randomised parallel study
design, 113 overweight subjects (BMI 29.3 (SD 2.5) kg/m2); age 45.1 (SD
10.4) years) followed a very-low-energy diet for 4 weeks, after which
there
was a 6-month period of WM. During WM, subjects were randomised into
either
a protein group or a control group. The protein group received 30 g/d
protein in addition to their own usual diet. During the very-low-energy
diet, no differences were observed between the groups. During WM, the
protein group showed a higher protein intake (18 % v. 15 %; P0.05), a
lower
weight regain (0.8 v. 3.0 kg; P0.05), a decreased waist circumference
(-1.2
(SD 0.7) v. 0.5 (SD 0.5 ) cm; P0.05) and a smaller increase in
respiratory
quotient (0.03 (SD 0.01) v. 0.07 0.01; (SD/)P 0.05) compared with the
control group. Weight regain in the protein group consisted of only
fat-free
mass, whereas the control group gained fat mass as well. Satiety in the
fasted state before breakfast increased significantly more in the
protein
group than in the control group. After 6 months follow-up, body weight
showed a significant group x time interaction. A protein intake of 18 %
compared with 15 % resulted in improved WM in overweight subjects after
a
weight loss of 7.5 %. This improved WM implied several factors, i.e.
improved body composition, fat distribution, substrate oxidation and
satiety.
Publication Types:
Clinical Trial
Randomized Controlled Trial
PMID: 15788122
Int J Obes Relat Metab Disord. 2004 Jan;28(1):57-64.
High protein intake sustains weight maintenance after body weight loss
in
humans.
Westerterp-Plantenga MS, Lejeune MP, Nijs I, van Ooijen M, Kovacs EM.
Department of Human Biology, Maastricht University, Maastricht, The
Netherlands.
BACKGROUND: A relatively high percentage of energy intake as protein has
been shown to increase satiety and decrease energy efficiency during
overfeeding. AIM: To investigate whether addition of protein may improve
weight maintenance by preventing or limiting weight regain after weight
loss
of 5-10% in moderately obese subjects. DESIGN OF THE STUDY: In a
randomized
parallel design, 148 male and female subjects (age 44.2 +/- 10.1 y; body
mass index (BMI) 29.5 +/- 2.5 kg/m2; body fat 37.2 +/- 5.0%) followed a
very
low-energy diet (2.1 MJ/day) during 4 weeks. For subsequent 3 months
weight-maintenance assessment, they were stratified according to age,
BMI,
body weight, restrained eating, and resting energy expenditure (REE),
and
randomized over two groups. Both groups visited the University with the
same
frequency, receiving the same counseling on demand by the dietitian. One
group (n=73) received 48.2 g/day additional protein to their diet.
Measurements at baseline, after weight loss, and after 3 months weight
maintenance were body weight, body composition, metabolic measurements,
appetite profile, eating attitude, and relevant blood parameters.
RESULTS:
Changes in body mass, waist circumference, REE, respiratory quotient
(RQ),
total energy expenditure (TEE), dietary restraint, fasting
blood-glucose,
insulin, triacylglycerol, leptin, beta-hydroxybutyrate, glycerol, and
free
fatty acids were significant during weight loss and did not differ
between
groups. During weight maintenance, the 'additional-protein group' showed
in
comparison to the nonadditional-protein group 18 vs 15 en% protein
intake, a
50% lower body weight regain only consisting of fat-free mass, a 50%
decreased energy efficiency, increased satiety while energy intake did
not
differ, and a lower increase in triacylglycerol and in leptin; REE, RQ,
TEE,
and increases in other blood parameters measured did not differ.
CONCLUSION:
A 20% higher protein intake, that is, 18% of energy vs 15% of energy
during
weight maintenance after weight loss, resulted in a 50% lower body
weight
regain, only consisting of fat-free mass, and related to increased
satiety
and decreased energy efficiency.
Publication Types:
Clinical Trial
Randomized Controlled Trial
PMID: 14710168
Cheers,
Michael C Price
----------------------------------------
http://mcp.longevity-report.com
http://www.hedweb.com/manworld.htm
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