Active No-Carber Forums

Nicola · Top Cat Joined: 21 Mar 2007 Posts: 379

In the absence of dietary carbs, the body converts glycogen (stored primarily in the liver and muscles) to glucose. Each gram of stored glycogen binds with 3 to 4 grams of water. So when a gram of glycogen is converted to glucose, 3 to 4 grams of water are also released. BTW, this accounts for the "supernaturally" fast loss of scale weight many people experience in the first week of a low-carb diet. It's mostly water weight associated with glycogen storage. Plus a gram of glycogen yields only about 4 kcal of energy, as opposed to about 9 kcal from a gram of fat. So, e.g., satisfy a 9 kcal deficit via burning fat, and you lose only 1 gram of weight, but satisfy it via burning glycogen, and you lose about 9/4 = 2.25 grams of glycogen plus 3 to 4 times that much again in associated water weight.

One of insulin's lesser-known effects is to increase sodium retention by the kidneys, and the more sodium stored, the more water the body retains. Insulin levels fall when fasting, which leads to sodium excretion, which leads to increased water excretion.

Nicola

Trem · Posted: Sun May 11, 2008 1:33 am Post subject:

Very interesting, thank you. I'm confused about glycogen.... does this mean that glycogen is depleted from muscles and needs to be replendished? I know that Bear mentions that even the most vigorous tests show no glycogen depletion after exercise, but there are many that seem to disagree. I always have a weak leg on VLC but as soon as I eat some carbs it gets strong again. I think this may be a sign of it.

Max Thunder · Hunter Joined: 12 Aug 2006 Posts: 231 Location: Canada

I don't understand Bear's talk about muscle glyocgen being unused; why would there be glycogen there in the first place, and why meat doesn't contain carb (I think the rigor mortis phenomenon depletes the muscles of their glycogen).

Your weak legs mean that you can't ketoadapt...

On VLC, muscle glycogen go down, muscle triglycerides go high. Fats and water don't mix, glycogen attracts water. As animals, by storing our energy mostly as fat, we avoid all the extra water and glucose weight that would come with glycogen. Plants don't care about that since they don't move.

People against low carbing keep saying that "the weight lost is water!" but that water weight is still weight, it also puts strain on your articulations and your heart still has to do extra work. A sprinting human doesn't need that weight. Anyway, we're not even at a point at which we still have to prove that low carb is much better for fat loss, it's been known for decades in the bodybuilding world.

Viking Dan · Carnivore King Joined: 21 May 2006 Posts: 551

Glycogen Storage: illusions of easy weight loss...
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Viking Dan
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jl53563 · Posted: Wed May 14, 2008 11:52 am Post subject:

Nicola · Top Cat Joined: 21 Mar 2007 Posts: 379

I found this on the Intermittent Fasting Yahoo Group and postet it to one of the journals - perhaps it's worth mentioning at this point too...

[Marlene Newell]
> Tim, I read this article:
>
> Glycogen storage: illusions of easy weight loss, excessive
> weight regain, and distortions in estimates
> of body composition
> http://www.ajcn. org/cgi/reprint/ 56/1/292S. pdf
>
> Let me see if I understand this article correctly.
>
> I eat 1800 extra calories of carbs,

So about 1800/4 = 450 grams, or about a pound. And let's assume these are non-fibrous carbs (i.e., they're carbs that metabolize to glucose).

> and my body stores it as 1 lb of glycogen, along with 3-4 lbs
> of water, making a weight gain of 4-5 lbs.

If your body stored it all as glycogen, yes. That's unlikely, though, after a single meal. Glycogen storage capacity is very limited. The two main storage sites (by total mass of glycogen stored) are:

The liver, which can be as much as 10% glycogen by weight. But the liver is only 3 - 3.5 pounds total, so 10% of that amounts to less than 6 ounces of glycogen storage capacity.

Muscle, which can hold far less glycogen as a percentage of its total weight than can the liver. But total muscle in the body weighs much more than the liver, and overall there's more total glycogen in the muscles than in the liver.
There's a very big difference between those sites: glycogen in the liver can be converted to blood glucose quickly, for use anywhere in the body, but glycogen in muscle tissue can be used only by the tissue it's stored in. For example, if exercise exhausts the glycogen stored in your thighs, glycogen stored in your biceps won't (can't) be metabolized to help your thighs do more work. Or if blood sugar falls too low for any reason, the glycogen stored in muscles can't help out (but liver glycogen can).

BTW, that's why vigorous physical activity is so important to improving insulin sensitivity: the muscles have the greatest capacity for "soaking up" glucose (as glycogen), but a muscle's glycogen is only depleted when that muscle is working hard. If a muscle is "full" of glycogen, it can't store more.

While there are other glycogen storage sites, the total amount of glycogen they store is insignificant compared to the amount stored in the liver and muscles. These other sites include the kidneys, intestines, fat cells, and glial cells in the brain.

> I have a calorie deficit of 1800, so my body uses that stored lb of
> glycogen, and I lose the 4-5 lbs. (glycogen plus the water)

If the calorie deficit was satisfied purely from burning glycogen, right.

> Rapid weight gain, rapid weight loss.

Or even more-rapid weight gain than weight loss: one of the major points in the paper is that muscle glycogen storage capacity can more than double if a period of low-carb eating is followed by one of high-carb eating -- the muscles can "overcompensate" with respect to glycogen. While the paper doesn't mention this, that's that basis for various "carb loading" schemes practiced by endurance athletes, "tricking" the muscles into temporarily storing more glycogen than normal.

> If, as the article says, the body stores glycogen in the fat cells,

I'm not sure why they mentioned that. That glycogen can be stored in fat cells is only mentioned once, in the first sentence of the abstract. It isn't mentioned at all in the body of the paper -- and it doesn't seem to be relevant to any of the paper's points. Most days I think abstracts should be outlawed .

Liver glycogen is the first to go. People routinely exhaust their liver glycogen stores. For example, it's quite possible that you use up all your liver glycogen every night while sleeping. Muscle glycogen is typically exhausted at a much slower rate, because only using a muscle can burn that muscle's glycogen stores. I'm not sure about the other storage sites, but the total amount of glycogen they contain just doesn't matter compared to the liver and muscle stores anyway.

> and uses the glycogen first when there's a deficit, then my fat cells would
> reduce, but I've not lost any actual fat. But, still the volume of the
> fat cells would reduce because of the removed glycogen and water. So my
> measurements would decrease.

It would be better if you forgot that the first sentence of the abstract contained "and fat cells" .

> I was suprised to read that the body stores glycogen in the fat cells.
> All other articles I've read about glycogen, as I recall, only mention
> the liver and the muscles.

In which care those articles were both incomplete and more helpful . Even this pretty exhaustive overview of glycogen metabolism doesn't mention that fat cells contain a bit of glycogen:

http://www.med. unibs.it/ ~marchesi/ glycogen. html

> I've read that the body converts excess glycogen into fat. Does this
> just mean that it stores the excess glycogen in the fat cells, or does
> it mean literally converting it to fat? I think it is the latter, but
> please correct me if I am wrong.

It must mean the latter, and must also be an oversimplification. There's no way to convert glycogen to fat directly. Glycogen to glucose, and then glucose to fat, yes -- but once glucose gets stored away as glycogen, it only (in the absence of a disease) gets converted back to glucose again if the body needs glucose for energy. In which case it will mostly be burned, or even converted back to glycogen again.

> My question is, When the body converts glycogen into fat, does it do so
> lb for lb? Does a lb of glycogen, which I only had to overeat 1800
> calories to get, convert into 1 lb of fat, which I now have to undereat
> 3500 calories to burn?

As above, I don't believe any significant lipogenesis (creation of fat) occurs starting from glycogen. For lipogenesis starting from simple sugars (like glucose & fructose), "a calorie is a calorie" sets a lower bound: it takes a little more than 9 kcal worth of sugars to synthesize a gram of pure fat, which is a bit heavier when stored because stored human fat is 10-15% water too (BTW, if a pound of human fat were pure fat, it would contain about 453.6 grams/lb x 9.1 kcal/gram ~= 4100 kcal/lb, not a tiny 3500 kcal/lb).

> And what does the body do with all that water that is in the glycogen?
> Does it stay in the fat cells? Is it used up during the conversion
> process? Is it disposed of by the body?

My understanding is that most of the freed water enters the bloodstream and is excreted in urine. After all, if it stayed in the body, the paper wouldn't have been talking about "illusions of easy weight loss" .

Nicola