las

Welcome all seeking refuge from low carb dogma!

“To kill an error is as good a service as, and sometimes even better than, the establishing of a new truth or fact”
~ Charles Darwin (it's evolutionary baybeee!)

Sunday, September 28, 2014

Disqus and moderation

Just a quick note.  I switched to Disqus quite a long while ago now due to Blogger's utterly inadequate moderation options.  I do have link moderation on.  I also have moderation on for first time commenters.  I try and "whitelist" people rapidly, as a goal of switching to this comment platform was to keep the discussion going even if I wasn't around to participate.  I think this has worked well on the whole.

Danged if I know why some whitelisters still have posts with links held up and some don't.  This appears quite random on my end.  But there are quite a few who simply escaped my notice to be whitelisted, and to those I do apologize.  

If your comments do not seem to appear or seem to always go to moderation and you think this is an error, it probably is.  Let me know in comments or via email (carbsane at gmail dot com) so I can fix that!      

:-)

Thursday, September 25, 2014

Mechanical Work, ATP, and Macronutrients (and Thermodynamics)

[Blogstress note:  this article is not similar to that in AARR recently mentioned here] 

In the background here I've been doing a lot of thinking and writing on thermodynamics and how the body uses food to produce internal energy to "do stuff".    In the end, we "burn" the macronutrient molecules in our food to release the chemical energy stored in those molecules, and ultimately we use that energy to do "work".  

I've said we can mostly ignore entropy in the context of the human body, but in chemical thermodynamics we have the concept of Gibbs free energy:  G.   Most importantly in chemistry, we are concerned with the change in free energy of reactions:

ΔGrxn  ΔHrxn  - TΔSrxn

ΔHrxn = change in enthalpy (energy)    ΔSrxn = change in entropy 
ΔGrxn = change in free energy

Free energy is the energy available to do work.  For example to move things such as the piston in an engine, an electron through a wire, or to move an ion from one side of a cell membrane to another.   In the human body, we are ultimately using energy derived from molecules in our food to support life by "powering" other chemical reactions (synthesis, etc.), and things like moving food through our digestive tract, generating nerve impulses, and moving our body parts to sit, stand, walk, run, etc.etc.  A sticking point for a lot of people with thermodynamics relates specifically to the context in which most first learn about entropy:  the combustion engine.   [You are invited to read some of my other posts on thermodynamics here: Of Thermodynamics, Chemistry, Biology and Biochemistry,  Of Thermodynamics, Complexity, Closed Systems & Equilibrium and A Fein(man), Fine Mess of Thermodynamics.]   In the human body, most of the "work" done directly by the chemical energy is electrochemical in nature.  Still, eventually we do somehow translate that into physical movement, aka mechanical work.

Some analogies can be drawn between a combustion engine and our electrochemical "engine", but others cannot.  A major distinction is that in the combustion engine, all of the chemical potential energy is released as heat, which creates pressure due to the gasseous products wanting to expand.  This pressure (force) acting on the piston moves it, thereby performing mechanical work.   In the human engine, the macromolecules are broken down and mostly converge at the point of a molecule called acetyl-CoA after which point the rest of the chemical "workings" of the engine are the same regardless of the original fuel source.  


In All Roads Lead Through Krebs, I included the graphic at right from Marks' Basic Medical Biochemistry.   This is the Tricarboxylic Acid Cycle or Krebs Cycle, and I've copied it here for reference.  Please refer to the post for other ways that some amino acids enter this cycle.  

Molecules often referred to as "reducing equivalents" (NADH, FADH2) are generated in this cycle, and these, along with reducing equivalents generated in fatty acid oxidation and glycolysis, are "fed into" what is called the Electron Transport Chain, or ETC.   Whatever chemical energy that is lost as heat along the way has already been lost at this point, so we are dealing with a predictable number of these reducing equivalents per acetyl-CoA entering the TCA/Krebs.  Unless you are a small animal such as a rodent, the ultimate outcome of the ETC is to use the electrochemical energy to power the phosphorylation of ADP to ATP.  In times when heat is needed, this process is diverted or "uncoupled" from ATP generation, but that is a topic for another day.


Moving Off the Grid ~ (analogy time again)

Let's say you want to move away from civilization and rely solely on energy you can harness on your property.  You find an ideal location with a strong running stream, frequent bursts of wind, and an open field.  Oh ... and you decide that rather than use powered exercise equipment you're going to harness the energy from those as well.  Only you hate cardio and learn that Tony Little has moved to the 100 acres next door, so you invite him to come over and use your Gazelle.

All of these are hooked up to a giant battery in your basement and everything in your home is run off of this Main Battery:  heat, light, appliances, etc.  [Note: this configuration is for the purposes of an analogy only.] So the water wheel basically charges the battery continually, the wind energy in short random intervals and the solar panel in cyclic daily fashion.  Tony, well, he just adds a little extra to make him feel good :-)    When you turn on your light bulb, it will illuminate if there is enough charge in your Main Battery.  Whatever wattage your bulb is will determine how much energy it drains from the battery over the time that it is used.  If you are using an inefficient old incandescent bulb to light your room, it drains more of the battery and gives off heat.  If you are using an energy efficient LED, it provides the same light while draining less energy and giving off virtually no heat.  
The light bulb draws energy from the Main Battery. It needs a certain amount to be illuminated.  Your light bulb doesn't care where the energy stored in the battery came from. 
The Main Battery provides energy based on the "load" that is placed on it.  Your battery doesn't care what it supplies energy for, or how efficiently that device uses the energy.

Adenosine Tri-Phosphate (ATP) ~ Your Main Battery


More than two thirds of all ATP generated is produced through the TCA/Krebs Cycle. The vast majority of cellular activities is powered directly by ATP. It would be fair to say that ATP is the equivalent of the "free energy available to do work".  It is also true that all ATP are alike regardless of where they came from. Therefore, from the point of ATP forward, all ATP-powered "work" and the thermodynamics, the energetics, whether or not entropy losses are involved, etc., all of it is the same. 

ATP is like the Main Battery in the previous example, only there is no central depot for this internal energy supply, but rather it is contained locally "on site" of every cell. I suppose an analogy could be made for our house that rather than a main battery, there would be some battery network at every socket or directly in the appliances and such. I don't think this is necessary to elaborate, however, in order to draw the following corollaries to the above arguments:
Walking requires ATP to do the mechanical work of muscle contraction. A certain amount of ATP is needed to produce the necessary muscle contractions, etc. The  muscle cells involved just use ATP and can't distinguish where it came from.
The amount of ATP required to perform a task is based on the "activity load" (speed, incline, etc.).   Each ATP provides the same amount of energy regardless of what activity it is fueling.  
So perhaps the water wheel is analogous to fatty acids continually cycling in your blood.  And perhaps the windmill is analogous to carbohydrates and the solar panel to amino acids.  Tony?  Why he's alcohol of course!  Pops by to add some energy during the week, perhaps he comes by more than once a day on the weekend.  :-)     

Dat Entropy ...


I recorded and put three short animations/tutorials available online here (Chapter 10) that shows how muscles contract and the role of ATP.  Direct link to my video.


Towards the end of the video when the ATP is attached to the myosin head, is broken down to ADP+P and transfers energy to the myosin head, and the subsequent movement that would be mechanical work is the "equivalent" of the expanding gasses in a combustion engine.  How much heat is lost in this process I don't know, but that wouldn't be entropy.  Are there entropy considerations so that the full energy stored in the ADP-P bond is not available to do the mechanical work?  Probably.  Does it matter?  Probably not. Not as far as tracing it back to any difference between macronutrient sources.  It would be the same for each ATP used in each specific application.


In Summary:


The "Burning:
  • All macros are broken down and converge on acetyl-CoA.  (Some amino acids feed directly into Krebs at different points)
  • The difference along the way is in some direct ATP formation, and the formation of different amounts of different reducing equivalents (NADH, FADH2).  
  • From acetyl-CoA on down the energy production line through TCA/Krebs and the ETC, all reactions are the same in the production of ATP.

The "Work"
  • Once energy is stored in the ATP "batteries", no cell knows the macronutrient origin of that energy.  
  • All ATP does whatever work -- chemical, electrochemical -- it does through the same reactions and mechanisms.  
  • Energy use or any losses associated with converting ATP chemical potential energy to other forms is the same regardless of the source of that ATP.

Saturday, September 20, 2014

Alan Aragon Research Review ~ Answering some questions about Thermodynamics

I'm once again honored to contribute to this month's edition of Alan Aragon's Research Review.  This time I was interviewed and answered the following questions:
 

This is premium subscription content, but AARR is always worth the price in my opinion!   Plus you'll get access to all archives (including past contributions from yours truly from the May-June issues of 2013 and 2014).

I missed getting to have my dedication in there, as I didn't think of it until after submission, but I wanted to dedicate the article to my grad school advisor Dr. Owen F. Devereux.   Dr. D died a couple years back or I would have been proud to send him my writings on thermodynamics.  He wrote a book called Topics in Metallurgical Thermodynamics that was his main area of research.  I called it the bane of my grad school existence, but really it wasn't.  Through applying the concepts of that book to my research I really learned and understood thermodynamics.  Folks often wonder what my seemingly irrelevant advanced degree has to do with any of this nutrition stuff.  Well, we applied the concepts to corrosion which is electrochemistry.   Biochemistry is living electrochemistry.  This means it involves enzymes and reaction coupling to get chemicals to do things they wouldn't otherwise do spontaneously.  But in the end the concepts are the same.  If you're a subscriber, I hope you'll enjoy!  If you're not, you might want to consider subscribing now ...

Friday, September 19, 2014

It's Question Time Again ... Saturated Fats

I have a few questions, but will stick to two.  Feel free to chime in with anything even remotely related!

Also, let me preface this by stating that I haven't had the time to deeply digest the various studies that have come down the pike lately exonerating saturated fats.  Any summaries or links to summaries would be greatly appreciated in this regard.  That said ...

1.  Has there ever been an RCT -- or even an uncontrolled trial -- where saturated fat intake was increased on an absolute level (preferably on a weight stable diet) and improvements were seen in cardiometabolic risk factors (or other health measures)?

2.  It is my understanding that mostly the effect (or lack thereof) of saturated fats have been assessed mostly in that 30-to-40% total fat range of the typical Western diet which usually puts sat fat in the 10-15% range.  Would you say this is correct?  If not, are there studies comparing a true low saturated fat diet to a high saturated fat diet?  I'll take any context here though weight maintaining would be preferred for obvious reasons.  Oh ... and coconut oil as major source of sat fat doesn't count since over half the fat is MCT.  So basically I'm asking about if there are any 5% vs. 15% studies to be found.

Thanks!!

Wednesday, September 17, 2014

Cholesterol or Inflammation?

I wanted to share this study with my blog readers that I had found and shared a bit of on Twitter a little while ago.  This has been prompted by ongoing discussions there and elsewhere on social media regarding blood lipids.  By "cholesterol" I am of course using the general term that in today's terms refers mostly to the low density lipoproteins or LDL.

C-Reactive Protein

A Simple Test to Help Predict Risk of Heart Attack and Stroke

This is not so much a study as a communication.  It is also on the "Cardiology Patient Page" of the journal Circulation, and as such quite readable.  I'd suggest any and all interested do so as I don't really have the time to go in depth into the entire thing.

Sunday, September 14, 2014

It's Official: Paleo is NOT Ancestral

not paleo
The underlying premise of the paleo diet is that we are supposedly consuming foods that our physiologies did not evolve to consume.  In order to get our diets back into concordance with evolution, it is necessary for us to look back. Waaaaaay back.  Nevermind that most of the problems are extremely modern -- as in within the past century modern, often even a matter of a few decades modern.  No ... we must look back millenia and tens of those to the paleolithic times.  Because ... evolution.

But even since I first heard of the paleo diet, and began reading about all of these remote ancestral tribes and cultures, there has been this nagging voice asking me how these populations can be translated back into the paleolithic.  Some of these tribes are decidedly neolithic despite their "primitive" cultures.  Any domestication of animals or cultivation of vegetation would be counter to the HG existence we are told we evolved through.  So in addition to looking to remote tribes for answers -- as opposed to looking to where diets in our own cultures went off the rails -- we are essentially being asked to make the leap that these modern "paleos" in some way mirror the true paleos, but we must ignore any facets of their diet that pre-date agriculture.  Hmmmph.

Friday, September 12, 2014

Disqus & Weston A. Price

Just a heads up here.  For some reason Disqus comments are not loading on my end.  Therefore I can read them in my dashboard but have been unable to respond today.  Hopefully this clears up as I have responses to many!

Meanwhile since I'm making a post ... I recently -- finally! -- got around to getting a copy of Weston A. Price's Nutrition and Physical Degeneration.  What I've read thus far has been rather underwhelming to be honest.  In addition I find parts to be quite difficult to read due to the overt racism (is it just me?) in many of his descriptions.  In any case, here's a question for you all.  Is this it for Price's writings or are there more in depth writings available somewhere from which various parts of this book were culled?  Thanks in advance!

Tuesday, September 9, 2014

Some comments on the Bazzano "LC" vs "LF" Study

So as the weighing in continues regarding:  Effects of Low-Carbohydrate and Low-Fat Diets (full text) I thought I'd add a little bit to the mix.  

First, I do believe the low carb advocates hailing this as any sort of endorsement for their high saturated fat, high animal fat, eat a ton of food, ketogenic or paleo diets need to all watch this entire video of Lydia Bazzano discussing the diet:

Friday, September 5, 2014

Channeling Nina Teicholz: Latest LC/LF Study Should Be Ignored

I'm sure by now you've heard ... low carb "bested" low fat once again in a gold standard randomized controlled clinical trial.  As usual, some weighed in even before the full article was published, but I guess this is to be expected these days.

Before discussing this study, perhaps next week, I wanted to point out that by the standards of Big Fat Surprise author Nina Teicholz, this study should be summarily dismissed.  Why?  Well:

Not Representative of the General Population


It was conducted in 148 obese adults of which 88% were female and 51% were black. Thus the results are not applicable to the general population. Teicholz relegated a well designed and implemented 2 year RCT on the Mediterranean diet to a footnote in her book for this reason. I discussed this in detail here, which was prompted by this footnote in BFS:

Thursday, September 4, 2014

A Question about the latest diet study ...

As you may have heard there's a new LC vs. LF diet RCT out there.  I'll have more to say about that when some time frees up, but I have had a chance to look at the full text and it is quite the horribly conducted study -- at least by the description put forth in a fairly highly regarded peer review journal.  (disturbing ....)  

In any case, the LC group was instructed to keep carbs under 40g per day.  If you arm a person with some tables of carb content or links to online databases, etc., this is a pretty straight forward and "simple" task.  By that I mean, disregarding any issues with compliance, the task remains an easy and straightforward one.

The LF group was instructed to reduce total fat to a maximum of 30% of calories and sat fat to a maximum of 7%.  We are then told that no calorie goals were specified (for either group).

Pray tell,  how does the LF group accomplish their goal?
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