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Old 04-01-2013, 09:38 PM   #1
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From a Biochemical Perspective

I'm a senior biochemistry student at my university, and one of the biggest things about a low carb lifestyle that stuck out to me is how scientifically accurate it is! In my class, we've been studying the molecular mechanisms of metabolism, including the breakdown of fatty acids (also called beta oxidation). This is the science behind low carb diets, as the lack of glucose causes our body to use fatty acids for energy. I thought I'd give some of the most interesting things I've found so far.

1. It's a myth that we can't live without carbohydrates. Believe it or not, when fatty acids are broken down completely, they become a molecule called acetyl-CoA, which through a series of reactions, can recreate glucose, which can be used to make important things, like DNA. We don't need to consume this glucose, though.

2. Fatty acid breakdown produces almost tenfold the energy of carbohydrate breakdown, and since we have a lot of fat to break down in our bodies (or at least me, anyway), this type of diet can truly lead to a greater amount of energy in everyday life.

3. It is true that to break down fatty acids, it takes a great deal of water, for what's called a hydratase reaction, so make sure you're drinking lots and lots of water. If you dehydrate, you may not be able to break down fats.

Those are probably the most interesting things I've found so far. I hope it gives everyone some food for thought. I hope everyone has a great night!

I have a test to go study for!
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Old 04-01-2013, 09:41 PM   #2
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THANKS SO MUCH for sharing this valuable interest straight from the lab, so to speak! Very interesting and affirming.
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Old 04-01-2013, 09:48 PM   #3
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Wow! I love reading stuff like this... I knew there was a reason I drank so much water It's always good to see the science behind LC because there are a lot of naysayers out there who think you NEED those carbs to be "healthy." We all know that isn't the case, but it's great to have science to back it up!

Thank you for posting this
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Old 04-01-2013, 09:57 PM   #4
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I wish all doctors would remember these classes from biochemistry! My organic chem prof was really into low carb and we would have great discussions in his office about it. I felt badly though because I caught him eating potato chips in his office one day He often added these types of discussions about ketones and breakdown of fats into his lectures and why sugar is bad, too. He had a huge thing for those potato chips though!
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Old 04-01-2013, 09:59 PM   #5
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Originally Posted by creseis View Post
I wish all doctors would remember these classes from biochemistry! My organic chem prof was really into low carb and we would have great discussions in his office about it. I felt badly though because I caught him eating potato chips in his office one day He often added these types of discussions about ketones and breakdown of fats into his lectures and why sugar is bad, too. He had a huge thing for those potato chips though!
We talk about low carb diets in class and have debates over it, and I'm the student who gets super aggressive and won't back down. Then, I feel pretty bad when I'm having a weak moment, sitting outside of class the next day clutching a Snickers wrapper between my hands, face covered in chocolate.
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Old 04-01-2013, 10:01 PM   #6
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Originally Posted by atomickate View Post
We talk about low carb diets in class and have debates over it, and I'm the student who gets super aggressive and won't back down. Then, I feel pretty bad when I'm having a weak moment, sitting outside of class the next day clutching a Snickers wrapper between my hands, face covered in chocolate.
hahaha my mom used to say, "Snickers has protein in it!!!"
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Old 04-01-2013, 11:20 PM   #7
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Originally Posted by atomickate View Post
Believe it or not, when fatty acids are broken down completely, they become a molecule called acetyl-CoA, which through a series of reactions, can recreate glucose, which can be used to make important things, like DNA.
PLEASE correct me if I'm mistaken because I'm not a science person! But I don't think fatty acids *technically* recreate glucose. The glycerol backbone of triglycerides can be converted to glucose through the process of gluconeogenesis. But only about 10% of triglycerides -- the glycerol portion -- can actually be converted to glucose.

My understanding -- and I may be misunderstanding what I've read -- is that acetyl-CoA produces energy in a way that is similar to the way that lactate, for example, anaerobically produces fuel, by producing an energy substrate that can be metabolized inside the cells to produce "adenosine triphosphate" (ATP), which fuels the body just as glucose produces ATP to fuel the body. But acetyl-CoA doesn't have to recreate glucose in order to produce that energy. It's a metabolic alternative to glycolysis rather than a recreation of glycolysis. Our cells are ultimately fueled by ATP, regardless of the source that is metabolized to produce ATP.

From BioCarta:
The Krebs cycle, also called the citric acid cycle, is a fundamental metabolic pathway involving eight enzymes essential for energy production through aerobic respiration, and, like glycolysis, arose early in evolution. This pathway is also an important source of biosynthetic building blocks used in gluconeogenesis, amino acid biosynthesis, and fatty acid biosynthesis. The Krebs cycle takes place in mitochondria where it oxidizes acetyl-CoA, releasing carbon dioxide and extracting energy primarily as the reduced high-energy electron carriers NADH and FADH2. NADH and FADH2 transfer chemical energy from metabolic intermediates to the electron transport chain to create a different form of energy, a gradient of protons across the inner mitochondrial membrane. The energy of the proton gradient in turn drives synthesis of the high-energy phosphate bonds in ATP, the common energy currency of the cell used to drive a huge variety of reactions and processes.An acetyl-CoA molecule (2 carbons) enters the cycle when citrate synthase condenses it with oxaloacetate (4 carbons) to create citrate (6 carbons). One source of the acetyl-CoA that enters the Krebs cycle is the conversion of pyruvate from glycolysis to acetyl-CoA by pyruvate dehydrogenase. Acetyl-CoA is a key metabolic junction, derived not only from glycolysis but also from the oxidation of fatty acids. As the cycle proceeds, the Krebs cycle intermediates are oxidized, transferring their energy to create reduced NADH and FADH2. The oxidation of the metabolic intermediates of the pathway also releases two carbon dioxide molecules for each acetyl-CoA that enters the cycle, leaving the net carbons the same with each turn of the cycle. This carbon dioxide, along with more released by pyruvate dehydrogenase, is the source of CO2 released into the atmosphere when you breathe. The Krebs cycle, like other metabolic pathways, is tightly regulated to efficiently meet the needs of the cell and the organis. The irreversible synthesis of acetyl-CoA from pyruvate by pyruvate dehydrogenase is one important regulatory step, and is inhibited by high concentrations of ATP that indicate abundant energy. Citrate synthase, alpha-ketoglutarate dehydrogenase and isocitrate dehydrogenase are all key regulatory steps in the cycle and are each inhibited by abundant energy in the cell, indicated through high concentrations of ATP or NADH. The activity of the Krebs cycle is closely linked to the availability of oxygen, although none of the steps in the pathway directly use oxygen. Oxygen is required for the electron transport chain to function, which recycles NADH back to NAD+ and FADH2 back to FADH, providing NAD+ and ADH required by enzymes in the Krebs cycle. If the oxygen supply to a muscle cell or a yeast cell is low, NAD+ and FADH levels fall, the Krebs cycle cannot proceed forward, and the cell must resort to fermentation to continue making ATP.Some Krebs cycle enzymes require non-protein cofactors for activity, such as thiamine, vitamin B1. Insufficient quantities of this vitamin in the diet leads to decreased activity of pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase, and a decrease in the ability of the Krebs cycle to meet metabolic demands, causing the disease beriberi.Although the elucidation of the Krebs cycle remains one of the landmarks of biochemistry, aspects of the Krebs cycle and its enzymes are still actively researched in the modern proteomic era.

Acetyl-CoA is also part of the energy-producing process of ketone body metabolism, which provides yet another form of metabolic energy -- which isn't technically fatty acids or glucose. Ketone metabolism can generate ATP just as glucose metabolism or fatty acid metabolism can generate ATP within the cells.

I'm totally not a scientist! So I'm probably wrong. But I just wanted to point this out to clear up my own potential misunderstanding of this process.
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Old 04-02-2013, 12:32 AM   #8
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good info here
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Old 04-02-2013, 02:12 AM   #9
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Thanks for sharing that
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Old 04-02-2013, 04:01 AM   #10
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Cool thanks for the info!
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Old 04-02-2013, 04:27 AM   #11
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And correct me if I am wrong, but I believe it is only protein that can be converted to glucose but it is slower process. That is why sprinters and endurance athletes prefer to fuel with carbs (faster conversion to glycogen and glucose) where as body builders prefer to fuel with proteins if following an SKD (slower process but more advantageous for muscle building/fat sparing).
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Old 04-02-2013, 05:47 AM   #12
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Quote:
Originally Posted by Trillex View Post
PLEASE correct me if I'm mistaken because I'm not a science person! But I don't think fatty acids *technically* recreate glucose. The glycerol backbone of triglycerides can be converted to glucose through the process of gluconeogenesis. But only about 10% of triglycerides -- the glycerol portion -- can actually be converted to glucose.

My understanding -- and I may be misunderstanding what I've read -- is that acetyl-CoA produces energy in a way that is similar to the way that lactate, for example, anaerobically produces fuel, by producing an energy substrate that can be metabolized inside the cells to produce "adenosine triphosphate" (ATP), which fuels the body just as glucose produces ATP to fuel the body. But acetyl-CoA doesn't have to recreate glucose in order to produce that energy. It's a metabolic alternative to glycolysis rather than a recreation of glycolysis. Our cells are ultimately fueled by ATP, regardless of the source that is metabolized to produce ATP.

From BioCarta:
The Krebs cycle, also called the citric acid cycle, is a fundamental metabolic pathway involving eight enzymes essential for energy production through aerobic respiration, and, like glycolysis, arose early in evolution. This pathway is also an important source of biosynthetic building blocks used in gluconeogenesis, amino acid biosynthesis, and fatty acid biosynthesis. The Krebs cycle takes place in mitochondria where it oxidizes acetyl-CoA, releasing carbon dioxide and extracting energy primarily as the reduced high-energy electron carriers NADH and FADH2. NADH and FADH2 transfer chemical energy from metabolic intermediates to the electron transport chain to create a different form of energy, a gradient of protons across the inner mitochondrial membrane. The energy of the proton gradient in turn drives synthesis of the high-energy phosphate bonds in ATP, the common energy currency of the cell used to drive a huge variety of reactions and processes.An acetyl-CoA molecule (2 carbons) enters the cycle when citrate synthase condenses it with oxaloacetate (4 carbons) to create citrate (6 carbons). One source of the acetyl-CoA that enters the Krebs cycle is the conversion of pyruvate from glycolysis to acetyl-CoA by pyruvate dehydrogenase. Acetyl-CoA is a key metabolic junction, derived not only from glycolysis but also from the oxidation of fatty acids. As the cycle proceeds, the Krebs cycle intermediates are oxidized, transferring their energy to create reduced NADH and FADH2. The oxidation of the metabolic intermediates of the pathway also releases two carbon dioxide molecules for each acetyl-CoA that enters the cycle, leaving the net carbons the same with each turn of the cycle. This carbon dioxide, along with more released by pyruvate dehydrogenase, is the source of CO2 released into the atmosphere when you breathe. The Krebs cycle, like other metabolic pathways, is tightly regulated to efficiently meet the needs of the cell and the organis. The irreversible synthesis of acetyl-CoA from pyruvate by pyruvate dehydrogenase is one important regulatory step, and is inhibited by high concentrations of ATP that indicate abundant energy. Citrate synthase, alpha-ketoglutarate dehydrogenase and isocitrate dehydrogenase are all key regulatory steps in the cycle and are each inhibited by abundant energy in the cell, indicated through high concentrations of ATP or NADH. The activity of the Krebs cycle is closely linked to the availability of oxygen, although none of the steps in the pathway directly use oxygen. Oxygen is required for the electron transport chain to function, which recycles NADH back to NAD+ and FADH2 back to FADH, providing NAD+ and ADH required by enzymes in the Krebs cycle. If the oxygen supply to a muscle cell or a yeast cell is low, NAD+ and FADH levels fall, the Krebs cycle cannot proceed forward, and the cell must resort to fermentation to continue making ATP.Some Krebs cycle enzymes require non-protein cofactors for activity, such as thiamine, vitamin B1. Insufficient quantities of this vitamin in the diet leads to decreased activity of pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase, and a decrease in the ability of the Krebs cycle to meet metabolic demands, causing the disease beriberi.Although the elucidation of the Krebs cycle remains one of the landmarks of biochemistry, aspects of the Krebs cycle and its enzymes are still actively researched in the modern proteomic era.
Acetyl-CoA is also part of the energy-producing process of ketone body metabolism, which provides yet another form of metabolic energy -- which isn't technically fatty acids or glucose. Ketone metabolism can generate ATP just as glucose metabolism or fatty acid metabolism can generate ATP within the cells.

I'm totally not a scientist! So I'm probably wrong. But I just wanted to point this out to clear up my own potential misunderstanding of this process.
For a "non science person" you definitely know a lot! This is very true. I wasn't stating that we produce a lot of glucose from our acetyl-CoA, but just enough to make sure we get into the pentose phosphate shuttle and create ribose sugars. I forgot to mention ketone body synthesis (maybe because I haven't memorized it for my test yet!)

Thanks for the correction
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Old 04-02-2013, 05:48 AM   #13
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Quote:
Originally Posted by Punkin View Post
And correct me if I am wrong, but I believe it is only protein that can be converted to glucose but it is slower process. That is why sprinters and endurance athletes prefer to fuel with carbs (faster conversion to glycogen and glucose) where as body builders prefer to fuel with proteins if following an SKD (slower process but more advantageous for muscle building/fat sparing).
Neither protein or fatty acids can be converted directly to glucose. Both convert back to acetyl-CoA and can undergo gluconeogenesis if the conditions are correct.
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Old 04-02-2013, 07:09 AM   #14
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Thanks for posting. I minored in biochemistry in grad school and also taught some college biology classes (basic metabolic reactions). I have recently been thinking that even the textbooks I learned from and used to teach with generally leaned towards carbohydrate metabolism as the main focus, then protein metabolism, and fatty acid catabolism and synthesis was kind of tacked on at the end - like, oh, maybe you should know about this too.... Glad to hear you are having debates in class about the utility of each in our bodies! Glad to hear things may have progressed in the last few years, at least at your school!
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Old 04-02-2013, 07:18 AM   #15
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Originally Posted by Trillex View Post
PLEASE correct me if I'm mistaken because I'm not a science person! But I don't think fatty acids *technically* recreate glucose. The glycerol backbone of triglycerides can be converted to glucose through the process of gluconeogenesis. But only about 10% of triglycerides -- the glycerol portion -- can actually be converted to glucose.

My understanding -- and I may be misunderstanding what I've read -- is that acetyl-CoA produces energy in a way that is similar to the way that lactate, for example, anaerobically produces fuel, by producing an energy substrate that can be metabolized inside the cells to produce "adenosine triphosphate" (ATP), which fuels the body just as glucose produces ATP to fuel the body. But acetyl-CoA doesn't have to recreate glucose in order to produce that energy. It's a metabolic alternative to glycolysis rather than a recreation of glycolysis. Our cells are ultimately fueled by ATP, regardless of the source that is metabolized to produce ATP.

From BioCarta:

(snip)

Acetyl-CoA is also part of the energy-producing process of ketone body metabolism, which provides yet another form of metabolic energy -- which isn't technically fatty acids or glucose. Ketone metabolism can generate ATP just as glucose metabolism or fatty acid metabolism can generate ATP within the cells.

I'm totally not a scientist! So I'm probably wrong. But I just wanted to point this out to clear up my own potential misunderstanding of this process.
Trillex,

I'm at work right now so I don't have a lot of time to make sure this is exactly right, but I found this article that states there is controversy over the idea that glucose can't be made from acetyl co-A and it is likely that most texts are wrong on this point:

Google: The Daily Lipid: We Really Can Make Glucose From Fatty Acids After All! O Textbook, How Thy Biochemistry Hast Deceived Me!

If true, I think it's great that atomickate's class is learning about this kind of stuff, and not just regurgitating what has been considered "the truth" for decades.
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Old 04-02-2013, 07:24 AM   #16
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Quote:
Originally Posted by Trillex View Post
PLEASE correct me if I'm mistaken because I'm not a science person! But I don't think fatty acids *technically* recreate glucose. The glycerol backbone of triglycerides can be converted to glucose through the process of gluconeogenesis. But only about 10% of triglycerides -- the glycerol portion -- can actually be converted to glucose.

My understanding -- and I may be misunderstanding what I've read -- is that acetyl-CoA produces energy in a way that is similar to the way that lactate, for example, anaerobically produces fuel, by producing an energy substrate that can be metabolized inside the cells to produce "adenosine triphosphate" (ATP), which fuels the body just as glucose produces ATP to fuel the body. But acetyl-CoA doesn't have to recreate glucose in order to produce that energy. It's a metabolic alternative to glycolysis rather than a recreation of glycolysis. Our cells are ultimately fueled by ATP, regardless of the source that is metabolized to produce ATP.

From BioCarta:
The Krebs cycle, also called the citric acid cycle, is a fundamental metabolic pathway involving eight enzymes essential for energy production through aerobic respiration, and, like glycolysis, arose early in evolution. This pathway is also an important source of biosynthetic building blocks used in gluconeogenesis, amino acid biosynthesis, and fatty acid biosynthesis. The Krebs cycle takes place in mitochondria where it oxidizes acetyl-CoA, releasing carbon dioxide and extracting energy primarily as the reduced high-energy electron carriers NADH and FADH2. NADH and FADH2 transfer chemical energy from metabolic intermediates to the electron transport chain to create a different form of energy, a gradient of protons across the inner mitochondrial membrane. The energy of the proton gradient in turn drives synthesis of the high-energy phosphate bonds in ATP, the common energy currency of the cell used to drive a huge variety of reactions and processes.An acetyl-CoA molecule (2 carbons) enters the cycle when citrate synthase condenses it with oxaloacetate (4 carbons) to create citrate (6 carbons). One source of the acetyl-CoA that enters the Krebs cycle is the conversion of pyruvate from glycolysis to acetyl-CoA by pyruvate dehydrogenase. Acetyl-CoA is a key metabolic junction, derived not only from glycolysis but also from the oxidation of fatty acids. As the cycle proceeds, the Krebs cycle intermediates are oxidized, transferring their energy to create reduced NADH and FADH2. The oxidation of the metabolic intermediates of the pathway also releases two carbon dioxide molecules for each acetyl-CoA that enters the cycle, leaving the net carbons the same with each turn of the cycle. This carbon dioxide, along with more released by pyruvate dehydrogenase, is the source of CO2 released into the atmosphere when you breathe. The Krebs cycle, like other metabolic pathways, is tightly regulated to efficiently meet the needs of the cell and the organis. The irreversible synthesis of acetyl-CoA from pyruvate by pyruvate dehydrogenase is one important regulatory step, and is inhibited by high concentrations of ATP that indicate abundant energy. Citrate synthase, alpha-ketoglutarate dehydrogenase and isocitrate dehydrogenase are all key regulatory steps in the cycle and are each inhibited by abundant energy in the cell, indicated through high concentrations of ATP or NADH. The activity of the Krebs cycle is closely linked to the availability of oxygen, although none of the steps in the pathway directly use oxygen. Oxygen is required for the electron transport chain to function, which recycles NADH back to NAD+ and FADH2 back to FADH, providing NAD+ and ADH required by enzymes in the Krebs cycle. If the oxygen supply to a muscle cell or a yeast cell is low, NAD+ and FADH levels fall, the Krebs cycle cannot proceed forward, and the cell must resort to fermentation to continue making ATP.Some Krebs cycle enzymes require non-protein cofactors for activity, such as thiamine, vitamin B1. Insufficient quantities of this vitamin in the diet leads to decreased activity of pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase, and a decrease in the ability of the Krebs cycle to meet metabolic demands, causing the disease beriberi.Although the elucidation of the Krebs cycle remains one of the landmarks of biochemistry, aspects of the Krebs cycle and its enzymes are still actively researched in the modern proteomic era.
Acetyl-CoA is also part of the energy-producing process of ketone body metabolism, which provides yet another form of metabolic energy -- which isn't technically fatty acids or glucose. Ketone metabolism can generate ATP just as glucose metabolism or fatty acid metabolism can generate ATP within the cells.

I'm totally not a scientist! So I'm probably wrong. But I just wanted to point this out to clear up my own potential misunderstanding of this process.
Correct, ketones are not converted to glucose, but glucose can be derived from fatty acids and other substances during gluconeogenesis, which also creates ketones and are used separately for energy.

Last edited by creseis; 04-02-2013 at 07:37 AM..
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Old 04-02-2013, 07:24 AM   #17
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It's a really awesome class! As we've been learning, we've been using our knowledge to actually debate low carb versus low fat diets. It's been a really interesting way of reinforcing the knowledge and showing that memorizing seemingly mindless pathways can be really useful.
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Old 04-02-2013, 07:36 AM   #18
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This makes me happy. Atomickate, Carry the torch forward for all of us. I basically got tired of trying to argue the case from a biochemical standpoint, and felt like people just thought I was making stuff up. and then when celebrities ruin everything and skew the media against it, it becomes intolerable to talk to regular people about it. I'm glad that the meaning of the science is being discussed and not just brushed under the table.

The last book I chose to read basically said all the same things,.... and then concluded that carbs are still necessary because we have not enough evidence that the entire chapter it just presented was actually true! It's biochemistry for goodness sakes,you don't have to "believe it" , it just IS.

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Old 04-02-2013, 07:38 AM   #19
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Gluconeogenesis - Wikipedia, the free encyclopedia

This is actually a very succinct summary of gluconeogenesis with figures and all if you have a basic understanding of organic chemical synthesis. I need to brush up on my biochemistry. This is more fun than working on my manuscript.
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Old 04-02-2013, 10:17 AM   #20
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I think the issue of whether or not glucose can by synthesized directly or indirectly from proteins and fats probably isn't the issue. I think the main reason why competitive athletes choose to fuel their workouts with carbs is because the process is much faster with carbs, and they can recover in such a short time. Its why they choose to incorporate carbs in their diet as opposed to staying ketogenic. Ketogenic is great for the average person whose main concern is fat loss. I think that is why carb cycling and targeted ketogenic diets were developed. More for athletes because of the benefits of incorporating carbs. The only other reason for eating carbs I see, for the average person is: if you like the taste of them and that they are a cheap source of food! Otherwise I don't think you need them at all.
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Old 04-02-2013, 11:58 AM   #21
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Most of my athlete friends are now eating low carb. It is the first year and first time for many of them. They are not elite athletes and most show signs of metabolic syndrome, like me, and do need to lose some fat and get a more efficient metabolism. I have one friend who is an elite athlete and is following a vegan diet. I am worried about it, but I keep my mouth shut because she has her mind set on this. I am wondering why vegan diets appear to be so successful for people like Bill Clinton and my friend, who seem to have lost a lot of fat and appear healthier. And then there is the example of Mr. 5 Times heart attack, President Eisenhower, who started the whole low fat kick and appeared very healthy and slim until his fifth heart attack finally killed him. So, in the short term, maybe veganism does something that appears good, but in the long term will lead to worse problems. I have other friends with a long history of coronary artery disease who switched from low carb to vegan and appear to be doing great and have doctors who blame a lot of the calcification in their arteries to eating a diet rich in cheese, although I have read studies that show no evidence of dairy products causing increased calcium in the blood stream or increased rates of calcification in the arterial walls, while taking calcium supplements do show increased rates of arterial wall thickening and calcification.

So, while it seems as though people do well or appear to do well on a vegan diet, I have huge reservations about it and I think a fear of fat drives people from looking at the biochemistry of a low carb/ketogenic diet, including many doctors.
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Old 04-02-2013, 12:13 PM   #22
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There is really so much controversy around LC v. LF. Interestingly, I showed my personal trainer my calorie tracking app this morning (and mind you I purposely didn't tell him I'm doing LC because he doesn't support it) and he was 100% on board with my diet over the last 6 weeks (since I started LC again). He sees it as very clean eating, nothing more, nothing less. he did encourage me to add a sweet potato in every few days, but I don't think I can handle it yet its funny how people react to the concept of LC. But don't label it and you've got it right.
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Old 04-02-2013, 12:55 PM   #23
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I'm studying for my test right now and finding what you mean about fat not being directly converted to glucose and I have a bit of an answer. I will get back to you when I'm not swamped!
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Old 04-02-2013, 01:59 PM   #24
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glucose isn't synthesized directly from fats and proteins, but from the byproducts of fat metabolism and protein breakdown gluconeogenesis can happen. It's not a direct path, but a way of recycling fuel.
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Old 04-02-2013, 11:38 PM   #25
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For a "non science person" you definitely know a lot! This is very true. I wasn't stating that we produce a lot of glucose from our acetyl-CoA, but just enough to make sure we get into the pentose phosphate shuttle and create ribose sugars. I forgot to mention ketone body synthesis (maybe because I haven't memorized it for my test yet!)

Thanks for the correction
I don't want to sound like I'm getting my info from *actual* science! Weirdly, most of my info about the human body comes from my brothers and close buddies who are all bodybuilders, and the Krebs Cycle is foundational to the modern practice of bodybuilding so it gets discussed a lot. I know guys who wouldn't be able to identify "H2O" as "water" but who can diagram the mitochondrial metabolic cycle from memory. Seriously.

Mitochondrial energy production is crazy vital for gym power, and different bodybuilding diet "cycles" have dramatically different macronutrient profiles, so competitive bodybuilders (and their nutrition coaches) try to address nutritional shifts with supplemental pyruvate and ornithine alpha-ketoglutarate, for example, to feed the ATP power cycle and compensate for the nutritional gaps of different diets. Lifting is anaerobic so, when bodybuilders are on ketogenic "cutting" cycles, they have to be able to rely on a sufficient stream of substrates that can be anaerobically metabolized to produce ATP. So bodybuilders get they get these metabolic details drilled into their brains by their coaches to guide them in the appropriate metabolic balance for times when glycogen is high and to compensate for when glycogen supplies are low. Believe it or not, these guys genuinely know the potential metabolic pathways of every nutritional component because, when they do something wrong, they feel it in the gym or see it in their body composition.

I get the girls at the research library here to help me look stuff up and check the details of what I've been taught by bodybuilders, because I'm totally fascinated by the intricate mechanisms of body recomposition, but I totally know that there are some potentially bizarre holes in what I *think* I know.

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I am wondering why vegan diets appear to be so successful for people like Bill Clinton and my friend, who seem to have lost a lot of fat and appear healthier. And then there is the example of Mr. 5 Times heart attack, President Eisenhower, who started the whole low fat kick and appeared very healthy and slim until his fifth heart attack finally killed him. So, in the short term, maybe veganism does something that appears good, but in the long term will lead to worse problems. I have other friends with a long history of coronary artery disease who switched from low carb to vegan and appear to be doing great and have doctors who blame a lot of the calcification in their arteries to eating a diet rich in cheese, although I have read studies that show no evidence of dairy products causing increased calcium in the blood stream or increased rates of calcification in the arterial walls, while taking calcium supplements do show increased rates of arterial wall thickening and calcification.

So, while it seems as though people do well or appear to do well on a vegan diet, I have huge reservations about it and I think a fear of fat drives people from looking at the biochemistry of a low carb/ketogenic diet, including many doctors.
My dad has been vegan since he was a teenager -- my parents were hippies. As a middle-aged black man, he is literally the ONLY one in his social circle who doesn't have any of the chronic diseases of aging (cardiovascular disease, arthritis, or diabetes), which is epidemic among middle-aged black Americans, and he is the ONLY one in his social circle who doesn't take any form of daily medication.

But my dad is a *healthy* vegan. He is extremely careful about keeping his nutrition balanced and keeping his calorie level high enough to support his metabolism. During the winter, for example, his diet is almost ketogenic, fed mostly by nuts, seeds, and oils. During the summer, he mostly eats raw but he juices fruits and veg to make sure he gets sufficient calorie density, adds brown rice protein powder to make sure he gets sufficient protein, and supplements with a vegan oil blend of essential fatty acids. My dad has notebooks of tables of his daily nutrition going back decades, in which he has written the weights and measures of everything he eats to make sure his nutrition is sufficient to support his life and activity level.

My dad is involved with some (often super annoying) vegan activist groups, so he meets a lot of young vegans and he kind of gossips to us in the family about how badly most young vegans eat. A lot of them eat nothing but sprouted-bean pancakes or organic udon noodles with tomato sauce -- zero essential nutrients.

Plus, being vegan isn't the same thing as being low-fat. I've gone to a lot of vegan events with my dad and the buffet is always DRIPPING with grease! Vegans eat nut butters and overly-oily hummus like there's no tomorrow.

I personally find Colin Campbell insufferably irritating. But he makes as good an epidemiological argument for the health benefits of vegan diets as the major low-carb researchers make for ketogenic diets. I think it comes down to your personal constitution, your personal preferences, and the type of dietary choices that you make within whichever nutritional plan you choose. I think it's probably easier to be an unhealthy, unbalanced vegan than to be unbalanced on a ketogenic diet because meat and vegetables have higher calories and more concentrated nutrients. But my dad's cohort of old hippies haven't eaten animal products for decades and they're doing hot yoga every day and their doctors freakin' love their health profiles.
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Old 04-03-2013, 12:32 AM   #26
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I wonder sometimes if what is more important is eating a 'conscious' diet as well as exercise and stress reduction.
Low carb omnivorous eating makes me feel well but I suspect if I put as much thought into my diet as your father does ,so would HIS vegan diet.
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Old 04-03-2013, 01:03 AM   #27
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I wonder sometimes if what is more important is eating a 'conscious' diet as well as exercise and stress reduction.
Low carb omnivorous eating makes me feel well but I suspect if I put as much thought into my diet as your father does ,so would HIS vegan diet.
Honestly, Kiwi, I respect my dad's detail-oriented adherence to his beliefs but I just cannot relate to it. He doesn't *enjoy* food the way other people enjoy food. According to my grandmother, my dad has never cared about the taste of food and has always just grudgingly eaten only because he has to eat to survive. My brothers are the same way. They're both bodybuilders and they eat just to achieve certain physical goals, with no appreciation for food being an enjoyable thing for most people. When my brothers are doing one of their mega-bulking diets where they have to eat specific nutrient percentages a bunch of times each day, they'll just mix protein powder with fish oil into a paste and eat it for most meals because it's fast. Ugh! They honestly don't care what it tastes like, as long as it fits the nutrient profile that they're supposed to be eating at that meal. It's so weird to me! My aging dad is stronger and healthier than I have ever been in my entire life and my brothers haven't been over 10% bodyfat in their entire adult lives. But neither lifestyle seems like it's worth the effort, to me. I can happily live without bread or sugar but I couldn't be happy without enjoying the food I'm eating. We all have different priorities, I guess.
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Old 04-03-2013, 01:17 AM   #28
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um yeah.urk. I think I prefer licking the butter off my fingers

I find your experiences fascinating as my husband is just getting into the gym seriously and it helps make a lot of the stories he brings home make more sense.
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Old 04-03-2013, 01:18 AM   #29
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I wish sometimes I was 'food as fuel'.I wouldn't be fat.Then the smell of dinner starts wafting out of the oven and I know that's not happening
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Old 04-03-2013, 05:53 AM   #30
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Just wanted to add that while we don't need carbs for to create energy, we still need vitamins, minerals and fibre to be healthy and these tend come in the form of carbs. There are some cultures that have evolved to exist mainly on fat and protein such as Innuits but most of us do genuinely need a vast array of vitamins to be healthy. The diseases such as rabbit starvation or scurvy come to mind. So while we don't need the carbs for energy creation, I personally think we should not be avoiding vegetables and some fruits (mainly berries). Even Atkins himself was quick to point out that it wasn't NO carb but LOW carb, with most of your carbs coming from vegetable sources.
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