6

votes

Gluconeogenesis?

Answered on August 19, 2014
Created June 01, 2012 at 2:06 AM

I study anatomy and physiology and my lecturer said that people usually go into a state of gluconeogenesis (conversion of amino acids and fats to carbs) in around 6-10 hours without eating. This state is brought on after the liver has run out of glycogen. Now if im not correct Mark Sisson, Brad pilon and Martin Berhkan all state that muscle wont be lost during a fast and that it is conserved by raised levels growth hormone. But if gluconeogensis occurs, does'nt that mean that GH is not doing its job as the IF advocates and Sisson state? Would we be losing muscle in a fast?

F8f38dfefde197df8ac1782ab6e65a60

(220)

on June 02, 2012
at 10:16 AM

Yes this makes sense too, its not all muscle amino acids, it can be from food and other tissues of the body.

F8f38dfefde197df8ac1782ab6e65a60

(220)

on June 02, 2012
at 10:16 AM

thanks for the input borofergie

F8f38dfefde197df8ac1782ab6e65a60

(220)

on June 02, 2012
at 10:15 AM

Thanks very interesting read.

B4e1fa6a8cf43d2b69d97a99dfca262c

(10255)

on June 01, 2012
at 04:44 PM

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2829942/?tool=pmcentrez

20203f15287a14924c714eb68a34ce6c

(596)

on June 01, 2012
at 02:54 PM

ok, juust to clear up what i said: you eat at 8pm, so 6-8hours before protein is finally sintethysed, either by shuffled into muscle, used for energy(oxidized) or then via gluconeogenesis turned into glucose. The main thing is that, despite the mechanism in the middle-and assuming adequate protein intake, the amino acids your utilizing when your fast come from dietary protein, not actually muscle beeing broken down.

64433a05384cd9717c1aa6bf7e98b661

(15236)

on June 01, 2012
at 02:45 PM

lactate is a byproduct of glycolysis

5662d1262516ccbd70249e7aeaf58901

(681)

on June 01, 2012
at 11:48 AM

Where are the lactate and amino acids coming from if you are fasting?

20203f15287a14924c714eb68a34ce6c

(596)

on June 01, 2012
at 09:18 AM

I' d like to underline heavily the point number 2, which some are forgeting here. ;) But the fast does not mean you dont have amino acids from the last protein meals, so it does not mean necessarly that the amino acid pool will be muscles,I can highly be the proteins from the last meals.

F8f38dfefde197df8ac1782ab6e65a60

(220)

on June 01, 2012
at 03:53 AM

interesting. What do you mean quality? Do you mean that the study showed that caloric restriction increases quality of muscle?

B4e1fa6a8cf43d2b69d97a99dfca262c

(10255)

on June 01, 2012
at 03:03 AM

i may not understand this correctly, but intact muscle is not the only other source of protein in the body once food sources have been exhausted. i read a study that examined the thigh muscle of exercised calorie restricted rats the found the quality of muscle fiber was greater than in the control group. i will have to find it!

68294383ced9a0eafc16133aa80d1905

(5795)

on June 01, 2012
at 02:53 AM

On a purely scientific basis, your lecturer is right. If gluconeogenesis occurs, the conversion takes place. From the perspective of some dude looking at his physique in the mirror before and after a fast, they would never notice a difference. Not only is it impossible to see but you then have to think about the number of places the muscle tissue could be taken from. A very little percentage of our muscle tissue is actually visible on the outside anyway.

68294383ced9a0eafc16133aa80d1905

(5795)

on June 01, 2012
at 02:52 AM

On a purely scientific basis, your lecturer is right. If gluconeogenesis occurs, the conversion takes place. From the perspective of some dude looking at his physique in the mirror before and after a fast, they would ever notice a difference. Not only is it impossible to see but you then have to think about the number of places the muscle tissue could be taken from. A very little percentage of our muscle tissue is actually visible on the outside anyway.

F8f38dfefde197df8ac1782ab6e65a60

(220)

on June 01, 2012
at 02:40 AM

ah i see now. So we do lose muscle, but its not really noticeable and if we workout out and re feed were pretty much two steps ahead. So muscle building is slightly slower but fat burning is maximal. Thankyou for your input!

F8f38dfefde197df8ac1782ab6e65a60

(220)

on June 01, 2012
at 02:31 AM

Thankyou. I never doubted Martin loses muscle, its just a contradiction of what my lecturer stated. There's a few gaps in paleo culture.

F8f38dfefde197df8ac1782ab6e65a60

(220)

on June 01, 2012
at 02:20 AM

Thankyou. I did not know that too much protein causes that, although it does make sense. Ever since researching paleo, i have discovered many contradictions in statements of the various paleo experts

6371f0ae0c075ded1b8cd30aafd4bf16

on June 01, 2012
at 02:13 AM

Great question. It can also be induced by eating too much protein.

  • F8f38dfefde197df8ac1782ab6e65a60

    asked by

    (220)
  • Views
    5.6K
  • Last Activity
    1433D AGO
Frontpage book

Get FREE instant access to our Paleo For Beginners Guide & 15 FREE Recipes!

6 Answers

4
68294383ced9a0eafc16133aa80d1905

(5795)

on June 01, 2012
at 02:36 AM

This is a great topic. Lets put it in simple terms.

  1. If gluconeogenes occurs, protein will be converted to glucose. This is a guarantee.

  2. In the absence of dietary protein, or in this instance, a completely fasted state, amino acids from muscle will be the source.

  3. Therefore, if this occurs, which it will, muscle will be lost in some capacity.

All of those guys you mentioned have great information and I greatly respect all of them. In practical terms, they are ALL correct. For most functional people and for the practicality of what we are able to measure visually or even tangibly, the muscle mass loss is NOT going to be significant enough for someone to notice it by looking in the mirror. Many of these same people who use fasting, are also re-feeding adequately after a fast, involved in other activities which stimulate and build new muscle tissue and therefore, over a period of time, will still see a net gain.

The best way I can think of it is counting from 0 to 100. Instead of going straight to 100, you go back 1 number for every 10 you reach. Eventually, you still get to 100 and over the long-term, you really never notice the difference in the trend from 0 to 100. I guess if you were able to take constant measurements of lean mass (this is impossible to do without any counteracting margin of error anyway) you may be able to notice the difference.

68294383ced9a0eafc16133aa80d1905

(5795)

on June 01, 2012
at 02:53 AM

On a purely scientific basis, your lecturer is right. If gluconeogenesis occurs, the conversion takes place. From the perspective of some dude looking at his physique in the mirror before and after a fast, they would never notice a difference. Not only is it impossible to see but you then have to think about the number of places the muscle tissue could be taken from. A very little percentage of our muscle tissue is actually visible on the outside anyway.

F8f38dfefde197df8ac1782ab6e65a60

(220)

on June 01, 2012
at 02:40 AM

ah i see now. So we do lose muscle, but its not really noticeable and if we workout out and re feed were pretty much two steps ahead. So muscle building is slightly slower but fat burning is maximal. Thankyou for your input!

68294383ced9a0eafc16133aa80d1905

(5795)

on June 01, 2012
at 02:52 AM

On a purely scientific basis, your lecturer is right. If gluconeogenesis occurs, the conversion takes place. From the perspective of some dude looking at his physique in the mirror before and after a fast, they would ever notice a difference. Not only is it impossible to see but you then have to think about the number of places the muscle tissue could be taken from. A very little percentage of our muscle tissue is actually visible on the outside anyway.

20203f15287a14924c714eb68a34ce6c

(596)

on June 01, 2012
at 09:18 AM

I' d like to underline heavily the point number 2, which some are forgeting here. ;) But the fast does not mean you dont have amino acids from the last protein meals, so it does not mean necessarly that the amino acid pool will be muscles,I can highly be the proteins from the last meals.

3
B3173217a49b5b0116078775a17eb21d

(11488)

on June 01, 2012
at 07:58 AM

Your liver doesn't have to be depleted of glycogen as a precursos to gluconeogenesis, neither do you have to eat an excess of protein (although both of those things will certainly induce it).

Gluconeogenesis is a natural part of your body's metabolism, and almost everyone utilises it every day. Dr Richard Feinman says this of gluconeogenesis on a "regular" diet: "It is true that your brain needs glucose, but glucose can be supplied by the process of gluconeogenesis; that is, glucose can be made from other things, notably protein. This is a normal process: when you wake up in the morning, between thirty and seventy percent of your blood glucose comes from gluconeogenesis." http://www.diabeteshealth.com/read/2008/12/25/5383/low-carbohydrate-diets-why-you-dont-want-the-experts-to-tell-you-what-to-eat/

So we're all engaged in gluconeogenesis every day, if we eat a high protein diet or not.

F8f38dfefde197df8ac1782ab6e65a60

(220)

on June 02, 2012
at 10:16 AM

thanks for the input borofergie

2
64433a05384cd9717c1aa6bf7e98b661

(15236)

on June 01, 2012
at 07:06 AM

I believe gluconeogenesis is always occurring, it's just the amount of its contribution that may change. Lactate is also a major substrate for it. Also, some of the output goes to refill liver glycogen, and in that case it is referred to as glyconeogenesis.

0
Bdc338593ffbb5e96ae8add27636b112

(0)

on April 24, 2013
at 09:49 PM

What I am confused about is if after a bout of fasted exercise if you then have a high protein meal what happens is your insulin raises slightly while glucagon soars to keep blood sugar high because there is little or no carbs in your meal. Beacuase of this glucogenesis needs to continue and therefore more of your muscle must be being wasted?

Also with low insulin levels due to lack of carbs how do the nutrients and what not get absorbed into your muscles to help with regrowth & repair???

Or am I being a fool and am missing something?? Any insights would be great!! :) Thanks, Dax

0
20203f15287a14924c714eb68a34ce6c

(596)

on June 01, 2012
at 09:15 AM

A little detail which some people are forgetting here: gluconeogenesis can have both substract from muscle aminoacids pool OR available aminoacids. The latter is the prefered if adequate amounts of protein are beeing delivered. The former is rather to occur if the latter are not present.

So, gluconeogenesis may mean the metabolic transaltion of lactate or amino acids for energy purposes,but not necessarly from muscle tissues.

64433a05384cd9717c1aa6bf7e98b661

(15236)

on June 01, 2012
at 02:45 PM

lactate is a byproduct of glycolysis

5662d1262516ccbd70249e7aeaf58901

(681)

on June 01, 2012
at 11:48 AM

Where are the lactate and amino acids coming from if you are fasting?

20203f15287a14924c714eb68a34ce6c

(596)

on June 01, 2012
at 02:54 PM

ok, juust to clear up what i said: you eat at 8pm, so 6-8hours before protein is finally sintethysed, either by shuffled into muscle, used for energy(oxidized) or then via gluconeogenesis turned into glucose. The main thing is that, despite the mechanism in the middle-and assuming adequate protein intake, the amino acids your utilizing when your fast come from dietary protein, not actually muscle beeing broken down.

F8f38dfefde197df8ac1782ab6e65a60

(220)

on June 02, 2012
at 10:16 AM

Yes this makes sense too, its not all muscle amino acids, it can be from food and other tissues of the body.

0
C3bc92e6b5eba45dc55f43ac3c70cc25

on June 01, 2012
at 02:27 AM

Doubt Martin or his followers are losing muscle. Besides, most of those IFers are using BCAA during the fast. Also consider Hard exercise can induce gluconeogensis. That's why post work out meals are highly anabolic. Muscle breaks down. you feed it properly. it'll adapt for size or strength

F8f38dfefde197df8ac1782ab6e65a60

(220)

on June 01, 2012
at 02:31 AM

Thankyou. I never doubted Martin loses muscle, its just a contradiction of what my lecturer stated. There's a few gaps in paleo culture.

Answer Question


Get FREE instant access to our
Paleo For Beginners Guide & 15 FREE Recipes!