160g a day : the xyzzy/Grazer hypothesis

[xyzzy]

Re: The Dangers of Wheat

So in English Stephen :lol:

You are making an hypothesis that my "half starchy carbs" or Grazers 130g is correct advice to give new members because:

1) Under around 160g / day your liver isn't full up so the carbs you eat go to filling it back up first rather than raising blood sugar levels.

2) As your body uses around a minimum 400 to 650 calories just to think and that equates to around that 160g figure then eating only 160g a day (or less) will ensure your liver never gets fully topped up.

If that's the case I find that perfectly true. I have been saying in recent posts how if you have consistently low carbed you seem to be able to get away with the occasional very carby meal with little consequence on BG's. Presumably this is also why you have to eat more than 150g / carbs per day to make a Glucose Tolerance Test valid or else the glucose in the test will just top up your liver rather than raise your levels.

Are you then saying if you eat more than 160g that the next thing that happens is the excess raise levels thus requiring an insulin response to take up the excess so it gets stored in muscle mass and that if your muscle storage is full it then gets converted to fat?

If that insulin response is impaired as in T2 are you saying that effectively encourages fat production because it becomes harder for the muscle mass to take up glucose or something like that? How does that effect exercise? Is that a good reason why people like myself who ate a healthy but high carb diet put on weight prior to getting T2

If the 160g thing is right why can I only eat 60 ?

All very interesting.

 

[borofergie]

1) Under around 160g / day your liver isn't full up so the carbs you eat go to filling it back up first rather than raising blood sugar levels.

Your liver is like a bucket with a hole in it. The hole leaks out about 160g of carbohydrate a day to feed your brain and muscles.

You can keep that bucket full, either by
1) Eating more than 160g of carbs a day.
2) Eating less than 160g carbs a day and using gluconeogenesis to make up the rest.

If you continually eat much more that 160g a day (and you're not some sort of super athlete), you'll fill up your bucket, and eventually it will overflow. Your body can cope with some of this spillage by oxidising carbs a bit faster (which isn't very clever), but pretty quickly the excess glucose will build up in your bloodstream (hyperglycemia) and eventually get converted to fat. The bucket can hold 600g maximum, but unless you exercise (and empty it a bit), then most days it will be almost full when you wake up.

This is standard human metabolism, and has nothing to do with diabetes.

xyzzy, at 60g a day you're filling your bucket using gluconeogenesis, which is like a slow drip compared to the gushing tap of a high carbohydrate diet.

 

[borofergie]

Re: The Dangers of Wheat

There is a third option:
3) Ketosis + gluconeogenesis, which effectively acts to reduce the size of the hole in the bucket. Meaning that less leaks out, so you need less to fill it up.

 

[Grazer]

Re: The Dangers of Wheat

Good stuff Stephen! I just need to re-read it about 100 times and I'll probably get it. But if it says 100-160 grams carbs a day is good, then that's near enough for this sheep!
Interestingly, I've been checking my carb intake recently and, as I said in another post, although my signature says 150 to 180 grams a day, I'm much nearer 150 than 180 on average.

You are making an hypothesis that my "half starchy carbs" or Grazers 130g is correct advice to give new members because:

Just to clarify, in case someone else picks up on it!, my little spiel is actually to try 50% of GDA, which is 150 for a man and 125 for a woman, then use testing to see if you can manage more or have to have less.

 

[xyzzy]

Re: The Dangers of Wheat

Right got that and apologies Grazer I was just trying to simplify.

So everyday my bucket (liver) fills up anyway either through the direct ingestion of the first 160g of carbs I eat or if I eat less the difference is made up either through my body creating the glucose required from other non carbohydrate sources (gluconeogenesis or gluconeogenesis + ketones) http://en.wikipedia.org/wiki/Gluconeogenesis

Right so here's what I don't quite get. If you eat a higher than 160g diet why does why does Metformin which suppresses gluconeogenesis work as a diabetic drug? Or is it that Metformin is only effective against the non carb bits of what you eat? Probably a stupid question with an obvious answer

 

[Grazer]

Re: The Dangers of Wheat

Right so here's what I don't quite get. If you eat a higher than 160g diet why does why does Metformin which suppresses gluconeogenesis work as a diabetic drug? Or is it that Metformin is only effective against the non carb bits of what you eat? Probably a stupid question with an obvious answer

No, think it's a great question! The article does suggest that metformin works by suppressing neogenesis. SO, first, does gluconeogenesis only occur when a person low carbs and the body needs an alternative source of energy? If so, as you suggest I think, Metformin wouldn't work (other than in it's second role of improving insulin sensitivity) UNLESS the person was low carbing. If, however, gluconeogenesis works with people on a normal high carb diet, then Metformin would still work on that part of the glucose producing process and would explain it's limited effect on BGs. Would also explain the insulin level issue we discussed on another thread where cheese etc was producing a large'ish insulin response as this would come from neogenesis despite igh carb eating.

 

[IanD]

Re: The Dangers of Wheat

The Hounslow dietitian (who gave me the high starchy carb advice in 2,000 now recommends 130 g carb daily rather the DUK's 300 + g.

 

[xyzzy]

Re: The Dangers of Wheat

Right so here's what I don't quite get. If you eat a higher than 160g diet why does why does Metformin which suppresses gluconeogenesis work as a diabetic drug? Or is it that Metformin is only effective against the non carb bits of what you eat? Probably a stupid question with an obvious answer

No, think it's a great question! The article does suggest that metformin works by suppressing neogenesis. SO, first, does gluconeogenesis only occur when a person low carbs and the body needs an alternative source of energy? If so, as you suggest I think, Metformin wouldn't work (other than in it's second role of improving insulin sensitivity) UNLESS the person was low carbing. If, however, gluconeogenesis works with people on a normal high carb diet, then Metformin would still work on that part of the glucose producing process and would explain it's limited effect on BGs. Would also explain the insulin level issue we discussed on another thread where cheese etc was producing a large'ish insulin response as this would come from neogenesis despite igh carb eating.

My next question is along a similar vein. If you are in deficit so that you are making up the difference required by gluconeogenesis is there a way you can relate that back to say your BMR in calorific terms so that you can optimise your body to generate the glucose required by gluconeogenesis from say your fat reserves as opposed to the non carby stuff you eat.

Effectively do you think if your calorific intake is less than your daily BMR AND you need gluconeogenesis to fill up the bucket that accounts for why a low carb regime is so good for weight loss?

 

[xyzzy]

Re: The Dangers of Wheat

The Hounslow dietitian (who gave me the high starchy carb advice in 2,000 now recommends 130 g carb daily rather the DUK's 300 + g.

Well Ian either you have acheived the nigh impossible (changing the mind of an NHS dietician :wink: ) or there's some retraining in low carb going on which as I mentioned the other week is known to be occurring in my PCT. Did they say if it was an officail thing or just that you had finally changed their opinion?

Either way more progress :clap:

 

[borofergie]

Re: The Dangers of Wheat

Gluconeogenesis happens all the time in everyone:

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. There is no requirement for dietary glucose.

Some of it happens as a bi-product of fat burning (from the "glyceride" bit in "tri-glyceride"), but mostly it's what happens to excess protein above and beyond what your body needs for structural tissue repair.

If you don't eat enough glucose to fuel your metabolism, and don't eat enough protein to fuel gluconeogenesis, your body will canabalise muscle to get enough protein to fuel enough gluconeogenesis to keep you going.

I think that we should split this thread...

 

[Scardoc]

I'm not disagreeing with any of these posts but I think there should be more consideration given to the fact that each and every one of us is different and that your BMR can be effected by a number of different factors including stress. Also, a lot of the facts and figures relate, as Borofergie pointed out, to standard human metabolism and have nothing to do with diabetes.

I am, however, a little confused by the fact and figures for glycogen storage:

"Glycogen storage capacity in man is approximately 15 g/kg body weight and can accommodate a gain of approximately 500 g before net lipid synthesis contributes to increasing body fat mass."

I am a man, I am approx 81kg which gives me a "bucket" of 1,215 grams which is twice what Borofergie says "Glycogen storage capacity in a human is 300-500g in muscle, and 70-100g in the liver." & "The bucket can hold 600g maximum". This is a huge difference.

 

[lucylocket61]

Can I have the LadyBird version of this process please? possibly with a diagram or flow chart.

I have read it times, but still cant quite grasp it.

sorry

 

[Grazer]

Can I have the LadyBird version of this process please? possibly with a diagram or flow chart.

I have read it times, but still cant quite grasp it.

sorry

:lol: :lol:

Here's my understanding in simple terms.
I'll let others correct me where I'm wrong!
Gluconeogenesis is the process whereby the body converts food sources (mainly protein) OTHER than carbohydrates into glucose. It occurs with low carbing where our carb intake isn't adequate to replenish the glycogen stores in the muscles and liver, which is our source of blood glucose reserves. It also occurs with normal high carb diets mainly at night, where glucose is still required but no fuel is taken on board by way of food. About 160 grams of carbs per day is required to provide the average person with the energy they need. If you eat more carbs than that, the liver and muscles will become full of glycogen, and excess glucose in the blood is instead stored as fat. If you eat less than that, then the liver and muscles are topped up with glycogen processed by gluconeogenesis from protein.
That's sort'ish how'ish it works, I think!
Does that Ladybird it, or did I misinterpret the entire question?

 

[phoenix]

I'm not disagreeing with any of these posts but I think there should be more consideration given to the fact that each and every one of us is different and that your BMR can be effected by a number of different factors including stress. Also, a lot of the facts and figures relate, as Borofergie pointed out, to standard human metabolism and have nothing to do with diabetes.

I am, however, a little confused by the fact and figures for glycogen storage:

"Glycogen storage capacity in man is approximately 15 g/kg body weight and can accommodate a gain of approximately 500 g before net lipid synthesis contributes to increasing body fat mass."

I am a man, I am approx 81kg which gives me a "bucket" of 1,215 grams which is twice what Borofergie says "Glycogen storage capacity in a human is 300-500g in muscle, and 70-100g in the liver." & "The bucket can hold 600g maximum". This is a huge difference.

I've just sent Stephen the link to this paper about nutrient fates in normal (non diabetic, non obese men) It is a review by one of the researchers who did the overfeeding study he described and which lead to this discussion (I think!)
http://journals.cambridge.org/download. ... fe7e2a40f0

The body’s glycogen reserves are small and are usually maintained at between 250 and
500 g in a 70 kg adult man. A normal maintenance diet provides about 250-300 g CHO/d,
which represents 50-100% of the total glycogen stores. From day-to-day, changes in the
body’s glycogen stores in the post-absorptive state are very small. This indicates that
within 24 h there is total oxidation of absorbed dietary CHO. It is to be emphasized that
other metabolic pathways for disposal of dietary CHO, such as conversion into TAG or
into non-essential amino acids, are not quantitatively important.

It was only after massive overfeeding over several days that glycogen stores were filled and new fat (de novo lipogenesis ) was created. Some pretty high intakes of carbs failed to do this.

after 3 d on a hypoenergetic low-CHO diet to deplete glycogen stores, a very large amount (740 g) of dietary CHO (with 60 g fat and 100 g protein), consumed during the 4th day by healthy young human subjects, induced an increase of 340 g in the glycogen store, without initiating de novo lipid synthesis at rates exceeding concomitant fat oxidation

ie some new fat was formed but the same amount was also burned, so no gain of new fat.
However, these were young fit men.
We haven't considered the fate of fats/proteins and the interaction of the different nutrients and the effect of insulin deficieny or resistance.
Complicated :lol:

 

[lucylocket61]

Thanks Grazer, got it :crazy:

So we need to compensate for low carb intake by increasing our protein intake to enable our bodies to produce the required glucose?

and to give weight loss, where needed, we reduce or at least be aware of our fat intake?

 

[borofergie]

"Glycogen storage capacity in man is approximately 15 g/kg body weight and can accommodate a gain of approximately 500 g before net lipid synthesis contributes to increasing body fat mass."

I am a man, I am approx 81kg which gives me a "bucket" of 1,215 grams which is twice what Borofergie says "Glycogen storage capacity in a human is 300-500g in muscle, and 70-100g in the liver." & "The bucket can hold 600g maximum". This is a huge difference.

I got my original numbers from Paul Jaminet's book. Here is some independent verification:

Untrained subjects eating a normal diet store about 280g of carbohydrate in their muscles (Hultman 1967; Blom, Costill et al 1987), wherase values of ip to 720g are usually found in trained athletes who have not exercised for 24 to 48 hours and who have allowed their muscles sufficient time to fill up their carbohydrate stores completely (Costill, Sherman, et al 1981).

Liver glycogen stores in untrained subjects are about 100g (Hultman and Nilsson 1971, 1973) and are increased to about 130g on a high carbohydrate diet.

So that's about 380g in an untrained subject, rising to about 830g in a highly trained athlete, which is consistent with what I said.

Of course the size of the bucket isn't really all that relevant (unless you are an athlete and empty your bucket frequently), because the 380g bucket will overflow just the same as a 830g bucket if its full.

 

[Grazer]

Thanks Grazer, got it :crazy:

So we need to compensate for low carb intake by increasing our protein intake to enable our bodies to produce the required glucose?

and to give weight loss, where needed, we reduce or at least be aware of our fat intake?

Nearly all there! First line is right.
In the second line, I'm not convinced about the fat intake wariness. If we balance out our carbs, proteins and fats to perfectly equal our glucose (and thus energy) requirements, we kind of stand still weight wise. If we reduce our carbs a lot, (below about 30 grams a day) and UP the fat a lot to balance out the totals we need, (keeping proteins about the same/higher), then neither the carbs or the gluconeogenesis can give us the glucose we need in total. Our body will be in ketosis and will use our existing fat supplies for energy instead. We thus burn our fat, get leaner and lose weight even though we're eating more fat (within limits!). That's kinda it, although this isn't my "specialist subject" as I don't go VERY low carb. Borofergie will answer the ketosis thing better than me (If you can understand him that is!) or at least correct me. As we know from many previous posts, this is quite contentious!

 

[borofergie]

I'm not disagreeing with any of these posts but I think there should be more consideration given to the fact that each and every one of us is different and that your BMR can be effected by a number of different factors including stress. Also, a lot of the facts and figures relate, as Borofergie pointed out, to standard human metabolism and have nothing to do with diabetes.

There will obviously be some variation between people, but it shouldn't be that big.

The bulk of your daily glucose use - 120g a day - is used by your central nervous system (mainly the brain). This number is more or less constant in all adults.

Muscle glycogen use obviously depends on how much muscle you have, and how much exercise you do, but actually, it's a relatively small drain on glycogen stores:

Highly trained runners utilize about 50 glycogen calories per mile (12.5g). Highly trained cyclists cycling at around 70% of maximum effort utilize about 500 glycogen calories per hour (125g)

Ordinary folk, exercising a low intensity for shorter periods of time, need very few extra glucose calories to maintain muscle glycogen levels. Someone who exercises 20 minutes per day at moderate intensity probably uses less that 50 glycogen calories (12.5g).

It's worth noting that at low-intensity - walking around and doing your daily business - your muscles operate almost entirely in fat burning mode.

As a mammal it's not surprising that our glucose use is so low - most mammals satisfy their requirements by manufacturing all the glucose they need in their liver, and not from eating it as carbohydrates. A fasting persons glucose production has been independently measured at 120 to 160g per day (fuelled entirely by gluconeogenesis):
http://www.ncbi.nlm.nih.gov/pubmed/3661 ... stractPlus

 

[tree-peony]

if all this is true, I would LOVE to know why my levels are still so high after nearly 3 months low carbing!
oh and I'm hardly losing any weight either!

 

[borofergie]

So we need to compensate for low carb intake by increasing our protein intake to enable our bodies to produce the required glucose?

and to give weight loss, where needed, we reduce or at least be aware of our fat intake?

Very low-carb is a special case, because "ketosis" is a starvation mode, where your body starts to burn fat in order to spare glucose supplies. Your brain starts to mainly burn ketones instead of glucose, and so you need less to produce less glucose to keep up.

On a VLC diet, you do need to increase your protein intake slightly, but not by much (it should be no more than 18% of your calories). If you eat much more protein than that, then it'll simply end up being converted to glucose anyway, and you might as well have eaten the carbs in the first place.