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    Yawn!

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    I love you Paleobird

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    I had a cat named Phoenix until recently. I love you too Derpums.

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    Quote Originally Posted by Derpamix View Post
    Aw qt name for a kitty
    I found her on 9/11.

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    Quote Originally Posted by Neckhammer View Post
    Right now we may believe we know what we know, but we assuredly don't know what we don't know.... and there is plenty of the latter. I'm sure that was said better by someone else, but I forget who or how it was stated. You get the gist of it though.

    Anthropology will always have the problem of too many variables, and lab science will always have the problem of reductionistic viewpoint to an extent that real world application isn't tenable in many cases. I don't see any reason to use either exclusively really.
    Nassim Taleb
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    Quote Originally Posted by secret agent girl View Post
    How does one determine whether it's right or not? And, what's the time frame? I don't want to hijack this thread, so links to where this has been discussed would be fine, if anyone would be willing to point me in their direction.
    6x a week cross fitters and children without medical disorders come to mind. Super skinny people or hard gainers trying to gain mass also. Then there are those who maybe give it a go and don't feel like they are thriving.
    Last edited by Neckhammer; 06-08-2013 at 08:11 AM.

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    Quote Originally Posted by Derpamix View Post
    Most people are so unhealthy that it doesn't work, and the damage it does in that state is severe. The same damage that got them to an insulin intolerant state in the first place. For these people, low carb is a band aid on a problem, not a solution.

    Also, you forget people are fucking idiots when it comes to knowing how they feel. Placebo controls their life, it's a very powerful thing, as we're all governed by quantum physics. Bunch of people say ketosis is a miracle = oh shit I'm a god ketosis saved my life I feel so great carbs are the devil I hate sugar wheat nearly killed me, and the nonsense goes on and on.
    Ah, but that begs to question.... is placebo (state of mind, belief, meditation, positive thinking....whatever) simply the strongest medicine with no side effects!

    You know I wonder if there as been any experiments aimed specifically at enhancing the placebo effect? Like a single blind trial with three arms placebo, placebo + doctor "letting it slip" that you are in the group getting the drug, and drug groups. Could be interesting to see how much we can maximize the placebo effect.

    BTW thank you for your earlier post. I think you got some good things to say also. I agree opposite ends of the spectrum can be civil. It gets touchy when that word "optimal" gets employed by either side though. Like I said optimal is a fantasy for the most part (well there may be N=1 optimal, but even that is tricky) until someone with the genetic predisposition to live 95 years makes it to 116. Then we gotta document those facts. Till then its hypothesis vs hypothesis.
    Last edited by Neckhammer; 06-08-2013 at 11:36 AM.

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    Quote Originally Posted by dilberryhoundog View Post
    Nassim Taleb
    Thank you!

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    Quote Originally Posted by Derpamix View Post
    The reason why fats produce more ATP coincides with the fact it oxidizes much slower. Fats have to be transported from fat cell tissue to metabolize in form of vesicles, which are taken up through endocytosis and degraded into fatty acids, then finally have to be converted into acetyl CoA before entering beta oxidation. Also, the fact fat contains an enormous amount of carbons and have to have already circulating oxygen in the cells in order to couple further slows this process. Also, fat oxidation produces huge amounts of water, which can burden the cells and respiratory system and cause lactic acid build up to take the place of the missing oxygen for energy, which shortens the ATP produced.

    I'll also assume you're talking about short chained fatty acids, as very long chain fatty acids cannot be used by the mitochondria and produce no ATP(peroxisome beta oxidation)
    Sorry to get back to this so late in the game, but, as it is wont to do, life has a habit of getting in the way of important things like posting here on MDA.

    Let me address your argument, such as it is, piece by piece. I can't promise that I will be linear in my approach, but I'll attempt to at least be comprehensive.

    Quote Originally Posted by Derpamix View Post
    The reason why fats produce more ATP coincides with the fact it oxidizes much slower.
    Proof by repeated assertion is not proof. It is merely annoying. You can chant this mantra until you are blue in the face, and it won't get you anywhere with me.

    You have to be careful when you get your knowledge from Wikipedia ... it may just lead to a superficial level of "understanding." With that said, your understanding of biochemistry is pretty mechanistic and you keep coming back with counts of the number of reaction steps involved in some metabolic pathway vs. another.

    I've already pointed out to you that the number of steps in such reactions is something of a red herring. What is far more important is the rate of reaction, which is to say that a reaction chain comprising several very fast reactions may occur in less time than one consisting of a single, albeit relatively slow, reaction. To this end, I've asked you about the kinetics of the various enzymes involved in oxidizing pyruvate and fatty acids, something that you've cleverly ignored. What I was asking for was velocity vs. substrate concentration curves. I'm fairly certain that these won't be forthcoming, so we'll just move on.

    Again, to reiterate, fats produce more ATP because they contain more carbon than glucose. Glucose is a 6 carbon molecule which metabolizes to two 3 carbon pyruvate molecules via a sequence of 10 reactions (!). Unlike pyruvate fats can be arbitrarily long but typically the predominant form in adipose tissue is palmitic acid, a 16 carbon saturated fat.

    Quote Originally Posted by Derpamix View Post
    I'll also assume you're talking about short chained fatty acids, as very long chain fatty acids cannot be used by the mitochondria and produce no ATP(peroxisome beta oxidation)
    No, I have been, and still am, talking about long chain fatty acids, specifically palmitic acid, where a long chain fatty acid is generally conceded to be fatty acids greater than 12 carbons in length, and less than 20ish carbons where we cross the threshold into very long chain fatty acids (VLC FAs). I fail to understand why you would assume that I would be talking about short chained and not medium or long chained fatty acids, especially as I've been making specific reference to palmitic acid all along? The less charitable side of my personality is prompting me to conclude that that is due to the fact that you don't actually know what palmitic acid is.

    Quote Originally Posted by Derpamix View Post
    Fats have to be transported from fat cell tissue to metabolize in form of vesicles, which are taken up through endocytosis and degraded into fatty acids, then finally have to be converted into acetyl CoA before entering beta oxidation.
    You are confusing triglycerides with fatty acids, and even then, you are quite far off the mark. The only source of triglycerides (TAG) in your plasma comes from dietary fat and as part of its absorption from the digestive system via the lymphatic system, it gets packaged in chylomicrons to render the TAG water soluble and therefore suitable for circulatory system distribution. Fatty acids ( note, _not_ chylomicron bound TAGs ) are how adipose tissue delivers it's contents to the rest of the cells of the body, and these are bound to plasma albumin.

    I was hoping to not have to do this, put you've forced my hand. This is how fatty acids enter a cell:



    So after you've looked at that diagram for a while, I would like you to point to the endocytosis step. Now, obviously, should you accept my challenge, I can't see what you are pointing to. Of course, I don't need to, because there is no endocytosis step depicted. Fats don't enter cells, fatty acids do, and they certainly don't do so by endocytosis, which is why any discussion about insulin and its fat metabolism effects always center on hormone sensitive lipase and lipoprotein lipase, which are the enzymes which liberate fatty acids from adipose tissue, and the enzymes which liberate fatty acids from chylomicrons, respectively as precursors to their uptake or release from cells.

    The reason I was hoping to not have to show the intricacies of cellular fatty acid uptake was because it is easy to get lost in the details. I ultimately went there because your understanding of things is rather odd, to put it mildly.

    And now, we come to beta oxidation. By this point, those that have keeping score should not be too surprised to find out that you have it not just a little wrong, but rather, exactly backwards. Beta oxidation is a 4 reaction chain that produces acetyl CoA from fatty acids for entry into the citric / TCA / Krebs cycle. Now I could beat this dead horse until it is as mangled as your understanding of oxidation, but I really don't see the point, although I will show you a diagram of what I'm talking about ( the bit in the yellow box comprises beta oxidation, the end product of which is AcoA ):



    Once you've formed acety CoA from you substrate, whether that is glucose, fats, or proteins, you have no chance of identifying which of those was the source at the level of the TCA cycle. It's just acetyl CoA, and we're off to the ATP generation races.

    Glycolysis produces two pyruvate molecules from one glucose molecule, which in turn provide two acetyl CoA molecules, sufficient to drive the TCA cycle twice. Every time through the beta oxidation cycle, two carbons are cleaved off the fatty acid, which means that beta oxidation of 16 carbon palmitic acid will provide sufficient acetyl CoA to drive the TCA cycle 8 times. Or, in other words, one palmitic acid molecule provides roughly 4 times the ATP of a glucose molecule upon oxidation.

    Quote Originally Posted by Derpamix View Post
    Also, fat oxidation produces huge amounts of water, which can burden the cells and respiratory system and cause lactic acid build up to take the place of the missing oxygen for energy, which shortens the ATP produced.
    I have no idea what in the world you are trying to say here. Lactic acid build up is caused by water? Are you serious?

    Each molecule of NADH+H and FADH2 that donates electrons to the electron transport chain winds up creating one H2O molecule. Each TCA cycle produces 3 NADH+H complexes, hence 3 molecules of H2O. So, each glucose molecule drives the TCA cycle twice, producing 6 H2O molecules. In addition, the conversion of pyruvate to ACoA by pyruvate dehydrogenase generates one NADH+H complex, and since we get two pyruvate molecules per glucose, the total H2O production from glucose oxidation in the ETC is 8 molecules.

    Beta oxidation produces one NADH+H complex and one FADH2 per ACoA molecule generated, meaning that if you get your ACoA from beta oxidation rather than glycolysis, you generate ... how much additional water? Care to chime in here, Derp? According to you, it's a "huge amount." When I do the math, we get ... two additional molecules of H2O from the additional FADH2 yield. In case you missed it, that's a rather modest increase of 25%.

    If at a cellular level, I have a requirement for, say, 120 ATP molecules, I can either oxidize 3 molecules of glucose, or 1 palmitic acid molecule. They both will yield the 120 ATP that I need, but the oxidation of the palmitic acid will also yield 25% more water. So ... assuming that I will concede that a 25% increase constitutes a "huge amount" of water, I wonder what a threefold increase in cellular water would constitute in your lexicon? Super duper ultra mega huge amount? What am I talking about? Well, if you recall, glucose and its metabolites are water soluble, which means that as they get sequstered or accumulate in a cell, they increase osmotic pressure, with the net result that water is driven into the cell. This is the by now well worn observation that for every gram of glycogen, you carry an additional 3-4 grams of water, the source of the miracle behind ketogenic diets, etc. etc. So, if we were playing water retention poker, at this point, I'd see your 25% and raise you 300%.

    There is so much here that is so wrong that I could go on, if I weren't limited to 10000 characters in a single post. So, I'm just going to stop. It's a little like shooting fish in a barrel.

    -PK
    My blog : cogitoergoedo.com

    Interested in Intermittent Fasting? This might help: part 1, part 2, part 3.

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