fat - the efficient fuel - just fyi

[mc]

Y'all hear probably know how fat is converted into energy and why it provides so much more energy for cells than carbs, but just in case you know someone who doesn't, here's a post that gives a way simple overview.

mc

[lovatof1]

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

cheers!
James

[mc]

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]

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]

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.

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]

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]

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.

[D-Rock]

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]

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"?

[mc]

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