Glucose or fructose to fill muscle glycogen stores?

[Marty]

I have been used (in the past) to thinking that fructose may be used to fill liver glycogen stores, but not muscle glycogen stores.


This dates back to someone-- a trainer-- indicating this during my college athletic years.

I assume now that it is the amount of sugars taken at a time that most heavily influences, rather than the type. Different sugars follow different metabolic pathways, of course... but still I assume now that it is the timing and amount of sugars much more so than the type that influences glycogen storage.

I find that taking sucrose with (mostly)-fructose fruit juices is what gives me longer-lasting energy, however, than just oil and fructose alone.

Please shed some light on this?

[Marty]

Meaning that...

Fruit juice + oil +sucrose seems to give me longer-lasting energy (and glycogen storage until the next day (?)) than

Fruit juice + oil + an amount of fructose (honey, or more fruit juice) equal in calories to that represented by sucrose in the above.

In other words: just having an added sugar (more calories) isn't what is making the difference.

[RRM]

I have been used (in the past) to thinking that fructose may be used to fill liver glycogen stores, but not muscle glycogen stores.

Its true that there are 2 types of glycogen: (1) less active, more phosphorylated and (2) more active, less phosphorylated glycogen. But regarding sports its about filling your glycogen depots, and the more filled up they are, the smaller the ratio of (2). And (1) is strongly influenced by both fructose and glucose conversion into glycogen (glucose-6-phosphate)
So, that you may use both glucose and fructose to fill up your muscle glycogen.
See this study

Funny enough, all glycogen is most potently composed when both glucose and fructose are present (as in sugar = sucrose = glucose + fructose)
Check out this study.

In the muscles, glucose and fructose are converted into glycogen by converting them into glucose-6-phosphate and fructose-6-phosphate (by hexokinase).
Fructose-6-phosphatase can be converted into glucose-6-phosphate, so that both can be converted into glucose-1-phosphate > (by triokinase) glyceraldehyde 3-phosphate > glycogen subsequently (plus inorganic phosphate).
The latter requires low levels of phosphate already present, by the way.
See this study and this study.

I assume now that it is the amount of sugars taken at a time that most heavily influences, rather than the type.

Exactly. And its about ingesting both glucose and fructose, which normally is most optimally the case when consuming fruits and/or sugar.
Also, when exercising, you should keep drinking high-sugar fluids, as this does not at all inhibit glycogen utilization by the muscles; its only supportive. See this study.

I find that taking sucrose with (mostly)-fructose fruit juices is what gives me longer-lasting energy, however, than just oil and fructose alone.

Fruits generally contain both glucose and fructose, and sucrose as well.
But it is true indeed, fructose alone is not converted into glycogen as efficiently.
To replenish your total muscle glycogen, especially the first few hours after exercise are important. The intake of 0.70g glucose/kg bodyweight seems to be the max; which is about 56 g / hour for an 80 kg man.

[Marty]

Many thanks for this answer; it is complete and extremely informative.

Many, many thanks.



On another note---
I had in past some problems digesting sucrose as it is a disaccharide; I seemed able only to digest simple sugars (monosaccharides) like those in honey and fruits (fruits do have sucrose, but in very small quantity; they are mostly fructose, a monosaccharide). Sucrose seems to be a very different substance to me now. It takes some lower gastrointestinal digestion to catalyze it; while monosaccharides do not need this type of process in the colon. So there is a digestion issue too that made it seem very important for me to avoid sucrose, which i do not now.

The above has helped elucidate not just the process you've described, but also made me see that some of the effect of a diet being 'more energy-giving' is simply that one is digesting everything better. Simply: being able to digest sucrose is in itself, for my system, an indication of utilizing energy better, and feeling more healthy. I can feel which effect is which now that all of these sugars are available to me, the diet works so well, and you have been able to explain some of the nuances of it, as in the above.

Thank you!

[RRM]

I had in past some problems digesting sucrose as it is a disaccharide; I seemed able only to digest simple sugars (monosaccharides) like those in honey and fruits (fruits do have sucrose, but in very small quantity; they are mostly fructose, a monosaccharide). Sucrose seems to be a very different substance to me now.

Maybe not...
Here are some fruit contents / 100 gram:

banana
3.6 gram glucose
3.4 gram fructose
10.3 gram sucrose

orange
2.3 gram glucose
2.6 gram fructose
3.4 gram sucrose

mandarin
1.7 gram glucose
1.3 gram fructose
7.1 gram sucrose

mango
0.9 gram glucose
2.6 gram fructose
9.0 gram surcose

muskmelon
1.6 gram glucose
1.3 gram fructose
9.5 gram sucrose

Simply: being able to digest sucrose is in itself, for my system, an indication of utilizing energy better, and feeling more healthy. I can feel which effect is which now that all of these sugars are available to me

Great!
Probably you have always been able to digest sucrose, but maybe couldnt cope that well with the foods it came from...

[Marty]

The diet works flawlessly. Sometimes there are many different questions behind questions that people ask. It is excellent to have your careful (and accurate) responses.


I must say you have the unenviable task of clearing up so much misinformation when you respond to posts.

But it is deeply appreciated!

[Marty]

As an additional note, I did eat almost 100% oranges, which are relatively high in fructose and low in sucrose, low-sugar fruits (avocado, tomato, cucumber), and a drink I made from olive oil, pure fructose, and Volvic water when I first began this diet a year ago, trying to keep things simple and run this diet against just a few variables... '

I suppose I will never know the sucrose/fructose answer in terms of digestibility, in the past.... But it is amazing how well the diet works now.

The few times I have had problems I have reverted to my version of the sample/strict diet, as above; it has always been helpful.
-Marthe

[RRM]

Ah, thats a smart thing to do. What is our safe haven (how much our system can cope with effortlessly) is indeed individually different.

It may help you to know all the fruits that, compared to most fruits, are lowest in sucrose relative to fructose:

(per 100 gram)
Raisin, sultana
31 g glucose
32 g fructose
1 g sucrose

sweet cherries
6.9 g glucose
6.1 g fructose
0.2 g sucrose

pear
1.7 g glucose
6.7 g fructose
1.8 g sucrose

prickly pear
6.5 g glucose
0.6 g fructose
0.0 g sucrose

grapes
7.2 g glucose
7.4 g fructose
0.4 g sucrose

kiwi
4.3 g glucose
4.6 g fructose
0.2 g sucrose

blackberries
3.0 g glucose
3.1 g fructose
0.2 g sucrose

persimmon (kakiplum; contains lots of tannins when not fully ripe, though)
7 g glucose
8 g fructose
1 g sucrose

figs (dried in this case)
25 g glucose
24 g fructose
6 g sucrose

strawberries
2.2 g glucose
2.3 g fructose
1.0 g sucrose

apple
2.0 g glucose
5.7 g fructose
2.6 g sucrose

avocado
0.1 g glucose
0.2 g fructose
0.1 g sucrose

raspberries
1.8 g glucose
2.1 g fructose
1.0 g sucrose

carambola
1.6 g glucose
1.2 g fructose
0.7 g sucrose

dried dates
25 g glucose
25 g fructose
14 g sucrose

watermelon
2.0 g glucose
3.9 g fructose
2.4 g sucrose

[Marty]

Oh thank you very much.


It jibes perfectly with what I (can) eat, even to this day, more successfully than other things.


I had colitis from the age of 12.... My lower gastrointestinal system has been sensitive... I have felt sure that fructose, a simple sugar, was metabolized not in the lower gastrointestinal system, but higher up... And sucrose needs the final catalysis along the intestinal wall.

I am not sure we each have a certain number of heartbeats, or cell replications, and we must stretch it out (a rather Daoist view)...maybe this site's too?...for I felt from having very bad colitis for over 20 years that it was more that one could reach the point of no return in the healing process. That is, when something is badly damaged and continues to be damaged, intentionally or not, without one backing off, it can never really heal. One can basically 'break' one's body. That is what I feel is true for the skin, too. All of the exfoliants and harsh treatments basically keep the face like a wound that is healing.... a very vulnerable position for the body to be in.

[RRM]

I had colitis from the age of 12.... sucrose needs the final catalysis along the intestinal wall.
...
I am not sure we each have a certain number of heartbeats, or cell replications ...maybe this site's too?...for I felt from having very bad colitis for over 20 years that it was more that one could reach the point of no return in the healing process.

Exactly right; replication rates of the cells involved will have been continously high, limiting the extend of recovery.
Due to limited total replication capcity, all cells are subject to aging phenomena, and it depends on what cells have aged the fastest where we break down first.

One can basically 'break' one's body. That is what I feel is true for the skin, too. All of the exfoliants and harsh treatments basically keep the face like a wound that is healing....

Precisely...

[Marty]

It is amazing to feel better.


Inserting my own observations about sugar type into this diet has been completely astonishing. It's more than effective.


Thank you of course for the diet but really for the diet followed by feedback. That is what makes 'a difference.'

I have the whole continuum of monosaccharide/disaccharide content of fruits perfectly lined out; in many ways it seems better to stay at one end of the spectrum for my body (digestion more than skin) for now, even with increased ability to handle sucrose.

Quite amazing. It is humbling to realize both the body's power and its limits to handle abuse.

[RRM]

Thank you of course for the diet but really for the diet followed by feedback. That is what makes 'a difference.'

You are welcome; you deserve it.
Not that others dont deserve it, but I personally feel that someone who wants to learn, and not just wants 'to receive help' really deserves it, and it makes helping such a person rewarding by itself.
So, thank you for being open minded and wanting to learn.

It is humbling to realize both the body's power and its limits to handle abuse.

Isnt it?
Our body is so perfectly and beautifully created; a miracle of ingeniousness.
Yet we succeed in making it malfunctioning, and think we can improve nature if we just spend a little more money on drugs research... We are so arrogant, and its so very much misplaced...

[Oscar]

Yeah, I'm really amazed that our bodies actually manage to survive that many years, considering the abuse.

[Marty]

Such very kind words.


The body has an organic memory of health that even surpasses the creations of the mind regarding what 'health' might be. It can find its way back, if you are open and receptive to this. It is a feeling of incredible spaciousness.

To put the pieces of the puzzle together in returning to health is like finding oneself at the end of a pathway, with the object of the search far greater than ever imagined.

Some people are disappointed when they finally reach their goal... there is nothing left to do. But others are humbled by the unexpected beauty of what they always longed for.