going to come off as wasted heat cant burn it or store it so one might think

Going to come off as wasted heat cant burn it or

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going to come off as wasted heat (can’t burn it or store it) so one might think that high protein diets will lead to greater weight loss But results from studies are inconclusive AAs that CONTRIBUTE to SDA - There’s some research to determine if you need all the AAs in a protein that you’re eating (which gives you the most thermogenic effect out of all the three macronutrients) Do you need all of the AAs in a protein to do this? NO. Studies in both animals and humans show Ile, Leu, S-containing AAs and Gly are primarily responsible for this in SDA. o Feeding a diet lacking those 4 AA’s = small SDA, Feeding a diet enriched with Ile = SDA (same with Gly and S-containing) o § Increased SDA seen with protein consumption is due to specific AAs and § you do not need intact protein This study and results can be repeated in animals if AAs in solution are given intravenously SIGNIFICANT INTER-INDIVIDUAL VARIATION OF SDA - Study looking at SDA in humans showed tremendous variability between individuals in how they respond to 3 macronutrients and the amount of SDA [ Nutr Metab :,1:5,2004 ] o w/i any one individual there’s 6 -30% difference in how they respond to the three macros - Inter-MAT study: Reviewed Leu intake in free-living populations worldwide [J Nutr 141: 249,2011] o Found that thinnest people had intake of BCAAs as % of total protein intake May be due to SDA; but shows that results are inconsistent between studies But there was not that much difference between quartiles (lowest quartile = 16.4% BCAAs, highest = 18.1% BCAAs)
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2/10/2014 32 CHO-FREE DIET = SDA = GLUCONEOGENESIS - Looked at SDA in people on a high protein, CHO-free [ AJCN 90:519, 2009 ] o Found high SDA and ~40% excess heat being given off from increased rate of gluconeogenesis Gluconeogenesis b/c brain still needs about 1/3 of NRG from CHO (glucose is preferred fuel source), so glucose on a CHO free diet comes from AAs via gluconeogenesis When CHO intake is su fficient, you don’t make a lot of ketones but once CHO intake falls then you make lots of ketones from the large amounts of fat that's oxidized. When ketone blood levels rise they cross the blood brain barrier and about 2/3 of brain can use ketones as alternate source of NRG o The SDA on a high protein/CHO-free diet is due to the extra heat given off due to increased gluconeogenesis and the rest is due to protein synthesis Minimum amount of CHO recommended to avoid ketosis= 50-80g CHO/d - On a starvation diet (only water) body can survive for 7-8 weeks. However this is significantly if the brain needed all of its NRG from glucose all the time. This is why the brain has an alternative source of NRG: ketone bodies - The only way you can get gl ucose if you’re not getting any from outside sources is through the breakdown of body protein and oxidation of AAs down to pyruvate and reverse glycolysis o The conversion of pyruvate to acetyl CoA is irreversible and that’s why you can’t synthesize glucose from fat o But when you oxidize FAs via β -oxidation for NRG you remove 2 Acetyl- CoA’s (which has pantothenic acid as a cofactor). Acetyl CoA can either be re-condensed to FAs or if you
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  • Spring '14
  • Knutson,MitchellD
  • Trp

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