Fat metabolism

(Ron) #4

“Ketones, which are water-soluble molecules that the liver makes when metabolizing fats, particularly when carbohydrate intake is low.
Ketones can be used for energy by most tissues in our bodies, including the brain (which cannot use fatty acids directly).”

This suggests that the liver makes ketones and then the body uses them for fuels. Ketones therefore are not just a by product. Note the parentheses section that states the brain cannot use fat.

Maybe this would explain it better for you -
http://www.srmuniv.ac.in/sites/default/files/files/KETONEBODYMETABOLISM.pdf

#5

ketones are created in the liver from fatty acids in the absence of carbohydrate. the absence of carbohydrate requires gluconeogenesis to occur to create the blood glucose you require, and that process does not allow all the molecules created by breaking fat (acetyl coA) to immediately enter the energy cycle (like they would if dietary glucose was present) so the acetyl coA is released into the blood stream where it forms ketone bodies and then is consumed by mitochondria elsewhere. this only happens in the liver.

fat that is released into the blood stream does not all get metabolized in the liver, most tissues can take in free fatty acids directly from the blood

the big picture though is an elaborate ochestration of the entire body to mobilize and efficiently use all 3 kinds of fuel (glucose for some of the brain, kidney and all red blood cells, ketone bodies for brain and heart, and fatty acids for everything else)

(Alec) #6

Ok, this makes sense to me. So the answer is both processes in my original post, depending on the demanding organ. Correct? But I am assuming that if the muscles are metabolising fatty acids, they do not produce ketones?
Cheers
Alec

#7

the only thing that produces ketones is the liver

(icky) #8

:joy::joy:
This is just like my thinking on so many of these subjects, hahaha :thinking: :roll_eyes: :face_with_raised_eyebrow: :upside_down_face:

(Bacon is a many-splendoured thing) #9

If you really want to get into it, start here:
https://peterattiamd.com/ketosis-advantaged-or-misunderstood-state-part-i/

(Alec) #10

Paul
This is what I wanted, this makes it clear. I thought the Krebs cycle was in there somewhere!! thanks.
Cheers
Alec

(Bacon is a many-splendoured thing) #11

Glad it helped. I love Dr. Attia, because he and Dr. Lustig got me started on this way of eating, but gloriosky, sometimes his lectures and posts are more information-dense than I can handle!

(Alec) #12

Paul
So, as I understand it, the only ketones that are made is in the liver during gluconeogenesis ie when we turn fat into glucose for use by the brain cos the brain can’t use fat.

Here’s my problem. Why then is everyone so obsessed with measuring ketones when it has nothing to do with us burning fat for fuel in the rest of our body?

It seems to me that being fat adapted is way more important than measuring ketones which is a marker of only a small portion of the overall fat burning process.

Am I understanding this wrong?
Cheers
Alec

(Ron) #13

Take a look at this. I believe there is more function than just the brain.

(Alec) #14

Ron
Any idea what “other” there is? It is not detailed in the article. Maybe the heart? But I am sure I have read somewhere that the “other” requirements were small?

Still leaving us with 2 pathways to metabolise fat:

  1. Through the liver using Gluconeogenesis, which creates ketones
  2. Through all other organs eg muscles, which will not create ketones

My understanding here is that pathway 1 is relatively small vs pathway 2. And we are all focussed on measuring pathway 1. Is that simply because we can? Or is it just as a marker that indicates that fat burning is also happening elsewhere in the body because if there was glucose about we would use that for the brain rather than use fat and gluconeogenesis?

Just trying to understand the focus on measuring ketones.
Cheers
Alec

(Ron) #15

This explains the other uses for ketones. I’m not sure myself about the focus on measuring as it seems futile to me.
http://www.srmuniv.ac.in/sites/default/files/files/KETONEBODYMETABOLISM.pdf

(Bacon is a many-splendoured thing) #16

You’re right, as far as I’m concerned. But we measure ketones because there is no way to measure directly how much fatty acid or ketone bodies the body is actually using. It’s an imperfect world (sigh).

Remember also, for what it’s worth, that ketone bodies are intermediate by-products of fatty acid metabolism, and some cells can start with fatty acids and metbolize them completely; they don’t need ketone bodies. But fatty acids can’t cross the blood-brain barrier, if I recall correctly, which is why the brain loves β-hydroxybutyrate.

Acetone (nail-polish remover) is what gives our breath that fruity smell, by the way. :apple: :banana:

(Alec) #17

Paul
One more question: we say that the liver creates glucose through gluconeogenesis and a by-product of that is keytones. So does the brain use the glucose or the keytones or both? As you say above, the brain uses the keytones for fuel, right, but it has also made the glucose to feed the brain… is it just using both?

Thanks for your help on this. It is just bugging me, and I want to be clear how the fat mechanism works.
Cheers
Alec

(Alec) #18

Ron, Paul
I think this slide from the pres Ron provided is close to explaining it. I am therefore taking it that the brain uses both the ketones and the glucose.
Cheers
Alec

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(Bacon is a many-splendoured thing) #19

Hey! You answered your own question! So what do you need me for? (Don’t answer that, lol!)

Yeah, that’s my understanding, too. The axons that lack mitochondria use glucose, the rest of the brain is fine with β-hydroxybutyrate. The red corpuscles in the blood also need glucose, because they lack mitochondria as well. And there are certain other cells that also need glucose, but I’m blanking on what they are at the moment.

(Ron) #20

Alec,
You might enjoy this thread if you haven’t seen it yet -

(Alec) #21

Ron
Thanks, but alas this is over my head. I’ve just run out of room in my head! :rofl:

#22

if you really want to explode your head

http://biochemical-pathways.com/#/map/1

(Alec) #23

This indicates to me that we know nothing. If we have to make it that complicated, we don’t understand it yet. :astonished::scream: