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fat - the efficient fuel - just fyi

mc

New member
Sorry, but that is way too many words for "simple". It's the kitchen sink, with fotos. :-D

cheers!
James

iguess context is important
sorry if that wasn't clear
what I presented *is* horribly simplified version of the fat conversion to ATP process. that's what I meant by "way simple" but perhaps simplifiedis a clearer term?

as such o shudder to think the kitchen sink would be closer to brooks fifth edition bioenergeyics
or going into detail about krebbs, kori and lipolysis I think

did you have a particular question or are you saying that the text is too dense?

I don't know that simple means brief always either?
e=mc2 is simple and brief
not sure how clear it is for someone not a physics geek?

so ya question or am I missing something you'd like me to take from your. comment for a future post?

or juzt dont use the word simple? :)

thank you

mc
 

lovatof1

New member
iguess context is important
sorry if that wasn't clear
what I presented *is* horribly simplified version of the fat conversion to ATP process. that's what I meant by "way simple" but perhaps simplifiedis a clearer term?

so ya question or am I missing something you'd like me to take from your. comment for a future post?

or juzt dont use the word simple? :)

thank you

mc

Just thinking back to how i was taught, "brief overview" is 5min or less when speaking or 500-1000 words of text, which is the same thing based on the reading ability of an average person, not a speed reader.

Synopsis is a synonym for this concept, and what you presented was a full article. I think you just wanted to trick people into reading more than they thought they would... ;-)

When you see the First Page of a published paper, its usually one or two paragraphs. That's a brief overview. You have dedicated sections to carbs and ATP, and "why" people would like to burn more fat than sticking to the "how". I say that only based on the assumption someone reading your article already is aware of the "why" on some level.

You have this wonderful desire to share information with us all, and we're grateful, but it takes a while to get to the meat(or is it.. fat?), with all the extra detail. Links to similar brief overviews or a few sentences on ATP, Carbs, protein, et. al, will give details to those interested in pursuing them, and allow those that desire the "fat" of the subject to get to it with ease.

cheers!
James
 

mc

New member
Just thinking back to how i was taught, "brief overview" is 5min or less when speaking or 500-1000 words of text, which is the same thing based on the reading ability of an average person, not a speed reader.

Synopsis is a synonym for this concept, and what you presented was a full article. I think you just wanted to trick people into reading more than they thought they would... ;-)

When you see the First Page of a published paper, its usually one or two paragraphs. That's a brief overview. You have dedicated sections to carbs and ATP, and "why" people would like to burn more fat than sticking to the "how". I say that only based on the assumption someone reading your article already is aware of the "why" on some level.

You have this wonderful desire to share information with us all, and we're grateful, but it takes a while to get to the meat(or is it.. fat?), with all the extra detail. Links to similar brief overviews or a few sentences on ATP, Carbs, protein, et. al, will give details to those interested in pursuing them, and allow those that desire the "fat" of the subject to get to it with ease.

cheers!
James

James my articles are free and worth every penny.:D

If i hear you right, when you see the term overview you expect
a shorter piece of about 1000 words. ( i didn't say brief, by the way)

This article is indeed 2281 words including figure captions.

And yes my goal is to overview how fat is synthesized into energy at a more or less plain language level - and that will still require a discussion of ATP, relation to carbs, protein and so on to create a context for how fat is used as energy.

hence the statement in the article "The goal of this article is to take a 50thousand foot view (ie really simplified view) at part of what's going on with that burn off, and why therefore fat is our super fuel and seemingly super nemesis."

but if that's not coming across, that's not coming across! time to revise.

so getting at the meat:

here's how the set up read
(brief blurb on role of fat followed by)
...And so we look for ways to burn it off.

The goal of this article is to take a 50thousand foot view (ie really simplified view) at part of what's going on with that burn off, and why therefore fat is our super fuel and seemingly super nemesis.

What i mean by simplified view? Here's a map of the metabolic process:
[image of vastness of metabolic processess]
We're considering a wee fraction of this and only partially of what's going on in here [image of simplified version of one postage stamp of process in that map]

These maps help to get that this is complex cool stuff. we are amazing. The above maps let us ask the question - how do we get the good stuff out of fat to use? and to appreciate how a little bit of fat goes a really really long way.
what i've now done is extended the last paragraph to be more explicit about what's reviewed in the post:

These maps help to get that this is complex cool stuff. we are amazing. The above maps let us ask the question - how do we get the good stuff out of fat to use? and to appreciate how a little bit of fat goes a really really long way. To get to that, we need to consider what energy from fat means. And that means taking a look at ATP, the primal fuel block (what fat and other nutrients in large part become), and also situating fat a bit relative to other nutrients like carbs and protein in this fuel-making process (nothing shines out like a comparison). We'll take a wee look at what can increase the fat burn in cells (mitochondria) and finally, where this should lead: why fat, while it burns all the time, is still a challenge to shed.
Hope that bit of extra mapping is an assist. each of the topics points to a header in the article. alas there's no easy way in blogger to make these into anchor tags. so hopefully scrolling and scanning willl be ok. Thank you,

best
mc
 

xafier

New member
Personally I have no problems with MC's long posts, but then, I have done a degree and enjoy reading books and scientific papers, so perhaps my attention span is longer than most.

I can understand where people are coming from, but to be fair to MC, he has basically condensed a topic which is worthy of an entire book into a few thousand words!
 

mettleman

Banned
MC - You mention that fat burns better in the presence of carbohydrates then in their absence. Could you expand on that a bit? I've heard it said but have never understood why and I don't ever see anyone advocating a no-carb diet anyway. It is my impression that carbohydrates raise insulin levels turning the body toward fat storage and actually blocking fat burning as well as producing triglycerides which are the only form of fat that can be stored in the body. This would lead me to say that it is possible to loose fat while eating carbohydrates but that it is not optimal, and that fat burning would be easier in the absence of carbs since we know that this state induces similarities with starvation. This is in exact oposition to your statement.

Is it possible that you mean that fat burns better in the presence of carbohydrates in people who are accustomed to eating carbohydrates, because their bodies have not yet developed the enzymes necessary to proces ketones and fats more efficiently? When carb-eaters go into ketosis ketones are excreted in the urine because they cannot be used efficiently - after a few weeks of easing into ketosis though, ketones all but cease to be excreted in the urine because they are being used by the organs and muscles.

Also, you mention fat as being a nemesis because of the density of the energy it contains although, typically, people who eat high-fat and protein and low-carb have a greater level of satiety and therefore tend to eat fewer total calories.
 
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D-Rock

New member
MC - You mention that fat burns better in the presence of carbohydrates then in their absence. Could you expand on that a bit?

Man, it's been like 20 years since I had to memorize glycolysis and the Krebs cycle. I seem to remember there being byproducts from glycolysis that are used in stages of the Krebs cycle in a feedback system. When fewer are available, the cycle slows and some reactions might not take place.

Damn, now I'm curious, but I'd have to go dig out my text from wherever I stored it.
 

mettleman

Banned
Thanks D-Rock, the other thing that I was getting at with that question though is that I have NEVER seen anyone advocate a diet that is zero carb as sustainable. So when would this even take place in a real life situation? Even on a ketogenic diet you may still be getting somewhere in the neighborhood of 20% of your diet from carbs. The body can also produce it's own glucose from dietary protein. When would the body need to burn fat in the "absence of carbs"?
 
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mc

New member
fat burning in the flame of carbohydrate - really it's FFA with Acetyl CoA and OOA

MC - You mention that fat burns better in the presence of carbohydrates then in their absence. Could you expand on that a bit? I've heard it said but have never understood why and I don't ever see anyone advocating a no-carb diet anyway. It is my impression that carbohydrates raise insulin levels turning the body toward fat storage and actually blocking fat burning as well as producing triglycerides which are the only form of fat that can be stored in the body. This would lead me to say that it is possible to loose fat while eating carbohydrates but that it is not optimal, and that fat burning would be easier in the absence of carbs since we know that this state induces similarities with starvation. This is in exact oposition to your statement.
first, sorry - i didn't see your post, and thanks D for stepping in. to rif a bit further on d-rock

second, i admire your desire to work this out and come to a conclusion, and arguing a position based on the evidence you have. good stuff. and that's likely the best conclusion you could come to based on the material you have, but alas, it's arguing in absence of the facts, as it were.

so d-rock has it right on. but let's step back a bit.

Always on, All the time - when possible

remember that all our energy systems are in play pretty much all the time. There's a little bit of glycolysis (carb burning) happening along with beta-oxidation (fat burning) even when we're at rest.

a by-product of the whole carb burning process is oxaloacetate (OOA). It connects with Acetyl-CoA to form citrate, and that gets processed in the citric acid cycle and ATP is produced.

Duel types of fat
Now here's the cool thing. Fat is so versatile it can get used as fuel a couple of ways. One of these - that produces the MOST ATP is via getting it into the citric acid cycle. This is what FFA's - free fatty acids do. Fat also becomes available as fuel as Glycerol. When you're low on carbs, it's glycerol that gets used as carbs (via gluconeogenisis) - whether you're doing a heavy workout or doing a ketogenic diet. BUT a molecule of glycerol only produces 19 ATP molecules.

FFA's Rock
Compare this rate of ATP availability with what FFA's do when they can enter the krebs cycle. It's also a relatively slow process so won't get energy to the muscles super quick. Which partially explains why even if you're on a ketogenic diet, most folks recommend getting some carbs into your system for better available energy - and fat utilization. Now this is not to say that we don't adapt in a ketogenic situation to get the turnover of fat into carb substitute happening faster, and when loads are reasonable, all could feel ok. But even so, that rate can't compete with FFA going through the citric acid cycle.

Fuel from FFA is FFA going into Citric Acid Cycle (burning in the flame of carb)
first step is beta-oxidation of a FFA: cleaving off a couple of carbons from the fat and we get products NADH and FADH2 which can form up into acetylCoA which can hook up with OOA to do the citric acid dance. This cycle in turn breaks down the acetylCoA into co2 and H. The H come out of the citric acid cycle to oxidize via something called phosphorylation. The result is 460 ATP from FFA conversion to energy.




Is it possible that you mean that fat burns better in the presence of carbohydrates in people who are accustomed to eating carbohydrates, because their bodies have not yet developed the enzymes necessary to proces ketones and fats more efficiently? When carb-eaters go into ketosis ketones are excreted in the urine because they cannot be used efficiently - after a few weeks of easing into ketosis though, ketones all but cease to be excreted in the urine because they are being used by the organs and muscles.

i hope the above shows that it doesn't matter whether you're adapted to gluconeogenisis or not. When fat can spin into the krebs cycle it produces more ATP.



Also, you mention fat as being a nemesis because of the density of the energy it contains although, typically, people who eat high-fat and protein and low-carb have a greater level of satiety and therefore tend to eat fewer total calories.

Er, there's not really evidence to suggest that it's the fat that's cuing satiety rather than the protein. And satiety is a way way complex and intrigued topic that i'm not gonna get into here.

Suffice it to say, and sorry this wasn't clear in the article - time to revise -
The point was really not about the consumption of fat at all but about fat that's already in the system. It's hard to burn off stored fat once we have it BECAUSE it provides so much energy from one little molecule compared to any other source of fuel.

We also have a lot of fats available as free fatty acids as opposed to glycerol when they get called into play. It's a 3ffa to one glycerol breakdown. So, good to get that FFA burning with some carbs.

This doesn't mean you have to eat a donut or pizza (oh no) but it DOES i hope show why even on a high fat diet, getting LOTS of veggies into one's system is a good idea. Fruit, really good too, as is the more carb dense things like legumes. Go spinach and lentils.


hope that helps.

mc
 

mettleman

Banned
Thanks MC for the clarifications! I'll have to chew on them for a while but I appreciate your well thought out response.

I didn't realize that the energy (ATP) difference was so great :19 ATP vs 460 ATP - that's huge. I know the question isn't black and white (because all of the processes are happening all of the time) but it seems like you're suggesting that the body cannot use the citric acid cycle (in conjuntion with gluconeogenisis) to sufficiently to meet the body's energy demands during endurace-type work while eating low-carb. Is that correct? Is there a threshold?

After the first 90 min on the bike what kind of fuel would Lance Armstrong's body be using predominantly and through which process? I ask because he is working at a very good intensity so I would assume that he has already burned most of the glycogen stores in the muscles and liver and is burning fat primarily for the duration - and it seems to work pretty well for him. Or is he eating carbs continually? I honestly don't know and don't follow the sport at all.

Thanks
 
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mc

New member
Thanks MC for the clarifications! I'll have to chew on them for a while but I appreciate your well thought out response.

I didn't realize that the energy (ATP) difference was so great :19 ATP vs 460 ATP - that's huge. I know the question isn't black and white (because all of the processes are happening all of the time) but it seems like you're suggesting that the body cannot use the citric acid cycle (in conjuntion with gluconeogenisis) to sufficiently to meet the body's energy demands during endurace-type work while eating low-carb. Is that correct?

It's not a suggestion it's a fact. now you know more about why. and why in the Ketogenic Diet - the best reference on this kind of eating - Lyle McDonald says if you're working out get some carbs happening.

saying it that boldly there are a few provisos:

how long is the endurance work?
what is the intensity?

vo2max oriented interval work is all about upping the ability of the body to be "glycogen sparing" so that it can horde those precious carb resources and get fat to burn. Now you know that with a little bit of carb in the mix, a whole lot of energy can come from fat - within aerobic activity. as soon as ya go anaerobic things change, and go all carb.

so more intense (anaerobic) efforts that rely on carbohydrates - like the intensity of a heavy lifting day. which is why some folks like energy drinks tho a lot of folks tend to overdo them, and the same effect can often be achieved by eating right to ensure carb availability.
 
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mc

New member
After the first 90 min on the bike what kind of fuel would Lance Armstrong's body be using predominantly and through which process? I ask because he is working at a very good intensity so I would assume that he has already burned most of the glycogen stores in the muscles and liver and is burning fat primarily for the duration - and it seems to work pretty well for him. Or is he eating carbs continually? I honestly don't know and don't follow the sport at all.

Thanks


fat.

fat fat fat

with goo (carbs) during to help perk energy and help keep fat turning.

the goal is still to be glycogen sparing so that by the time an anaerobic sprint hits, or a big hill, the fuel is there to sustain a 30sec to 3 mins burst. that's all the full time you get with a carb jolt before recovery/refuel/resynth needed.

mc
 

mettleman

Banned
Awesome - Thank You!

Well, I had to do a little more research to try and straighten this out. These are a few things that I found to support the idea that performance does not suffer in a ketogenic diet that the subjects have had adequate time to adjust to.

First off, I am defining a low-carb diet as one where less than 25% of the calories are derived from carbs. A lot of research has been done on "low-carb" diets without defining the term - and many of those diets can be as high as 50% carbs making their results impossible to compare with a diet that is closer to 25% or less.

Very few studies have been done at truly low-carb levels and with the time to adapt where the conversion and real benefits seem to take place. Only very low levels of carbohydrate can be consumed to access fat effectively enough for these benefits.

Here are a few studies:

Dr. Stephen Phinney Study 1983:
• Noted that previous studies hadn't allowed enough time for subjects to adapt to a ketogenic diet
• Subjects were lean, healthy, aerobically trained cyclists
• Let cyclists adapt over 4 weeks and thought that they'd do better if they were allowed to adapt even longer
• Used a diet of 83-85% fat and containing less than 20g of carbohydrate per day
• concluded that these cyclists could maintain performance after being pitted against cyclists eating a high-carb diet.

-Phinney SD, Bistrain B, Wolfe RR, Blackburn GL. The human metabolic response to chronic ketosis without caloric restriction: physical and biochemichal adaptation. Metabolism 32(8):757-768, 1983
-Phinney SD, Bistrain B, Evans WJ, Gervino E, Blackburn GL. The human metabolic response to chronic ketosis without caloric restriction: preservation of submaximal exercise capability with reduced carbohydrate oxidation. Metabolism 32(8): 769-775, 1983

In 1984 DH Williamson performed a study on male rats:
• 2 groups of rats were fed 78% of their calories as fat and another two groups given 69% calories as carbs
• Some animals were sacrificed and tested at either 1 or 5 weeks ( some in a resting condition and some after exhaustive exercise.
• After one week the high-fat animals ran 8% longer before becoming exhausted
• On the 5th week the high fat animals ran 33% longer
• Both groups became exhausted at about 40 minutes
• At week five it appeared that liver glycogen was rebounding in the high-fat animals despite low carbohydrate intake.
• The activity of two enzymes that dictate an increase in fat burning increased by 77% and 98% respectively
• Researchers concluded that, through dietary manipulation alone, prolonged and intense exercise performance could be improved dramatically - despite profoundly limited glycogen content.

Miller WC, Bryce GR, Conlee RK. Adaptations to a high-fat diet that increase exercise endurance in male rats. JAP 56(1): 78-83, 1984.

Dr. R. Conlee, from the study above, also wrote after conducting his own research in 1987, that
"All of these facts indicate that, in spite of the opinion among the scientific community regarding the limitations of fat as an energy substrate, there may be experimental conditions not yet designed under which the disadvantages of fat and, conversely, the advantages of carbohydrate for energy production may not be as poalrized as the present literature leads us to beleive."

This is a good one from 1991:
After seeing the above study with the rats a group of French researchers got the idea to do a similar experiment but using 0% carbs on one group and 62% carbs on another:
• Before the study the rats were trained until the scientists were certain that they could sustaing one hr of exercise at 80% of their max.
• The rats were allowed to adapt to their diets and training for 12 weeks
• Low-carb rats experienced exhaustion after 68 min
• High-carb rats became exhausted after 42 min
• At the end of five hours 75% of the high-carbers were still trucking but 83% of the low-carbers were still going.
• At the end of five hours the rats were encouraged to run until completely exhausted
• All of the carb-feds were tuckered at seven hours where six of the fat-feeders had to be stopped at 7.5hrs

Simi B, Sempore B, Maynet MH, Favier RJ. Additive effects of training and high-fat diet on energy metabolism during exercise. JAP 71(1): 197-203, 19991.

OK I'm sick of typing and reading for now - WHEW!

Perhaps fat is even more efficient that we all thought? AND it's GOOD for you! Don't get me going on that.
 
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mc

New member
mettleman
i love your enthusiasm but please consider the date of the studies and the claims you are making from them. It's not feasible to stay
"Very few studies have been done at truly low-carb levels and with the time to adapt where the conversion and real benefits seem to take place. Only very low levels of carbohydrate can be consumed to access fat effectively enough for these benefits."
when you're citing something from 25 years ago - a lot's happened since then,

but what are you trying to show

that you can do ok on low carb? yes no one's saying you can't. Can you train anaerobically as an athlete well? That's not tested. 20g carbs a day for someoone training hard (anerobically) for 30-min a day is not optimal. more legumes and veggies for that person.

the best source for this stuff without doing the current primary research yourself in mcdonald. i really recommend you read it. it explains the physiology brilliantly.

There's not much remarkable though in the one study presented when you unpack it - if you look at phinney 2004
I can't find the 83
he's trying to unpack why the endurance athletes on low carb performed relatively the same as nonrestricted carb cyclists.

Well, let's try that the event tests were 65% max HR
in other words, aerobic. barely. 65% max HR can be achieved with a brisk walking pace.

Your question about lance armstrong above? even though he has one of the lowest heart rates in the world, most of the time they're 75-85% or higher of MaxHR, so regularly pushing anaerobically.

So it pretty much depends what you're doing how well a certain diet will support you.
That said we are marvelously adaptive, and metabolic flexibility will do its best to help us survive on anything we have available.
so if you want to do it - and it seems you do - go ahead.

but if so, get lyles book it's great. excellent research, explanations and guidance. and even he says if you're doing anaerobic workouts, have some carbs. and as said before that doesn't mean having to eat pizza (though why not?) but it does mean having a decent cash of carbs available for that effort.

mc
 
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mettleman

Banned
I'll put the book on my list - thanks for the suggestion.

I'm not disputing that there is a time and place for eating carbs - I even use them peri-workout but still keep my daily total around 20-25% - I just don't think people need to rely on them so much and that people are afraid of fat when they should not be (with the exception of vegetable oils and tras-fats). Although eating high-fat and high-carb is disasterous. A year after I began to cut carbs out of my diet my bodyfat went down (it was only about 14% to begin with), my triglycerides fell into the "ideal" range, along with HDLs and LDLs and I generally felt much better than when I was eating moderate amounts with lower fat.

People should certainly eat carbs if they have use for them. Otherwise, I do believe that it is wiser to avoid eating them just because they exist.
 
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