Ashley Moran wrote:

>> People who start out on ketogenic diets may well find that they  have 
>> no fight or flight reserves for a while.  They may feel  sluggish for 
>> a week or so.  But as more tissues that can burn fat  do so, as those 
>> that can burn ketones do so,  the actual demand for  glucose goes 
>> down.  It doesn't happen overnight.  These people will  also become 
>> more efficient at gluconeogenesis, so their glycogen  reserves will 
>> be gradually replenished.  In short, they achieve a  different 
>> metabolic equilibrium.
>
>
> This makes a lot of sense.  Assuming this is all correct it means  
> that low glycogen should be just a withdrawl symptom from excess  
> carbs, and that it will be replenished as your body adapts to  
> ketosis.  I assume that glycogen is replenished much more slowly from  
> glucogenesis than from dietary carbs, hence the dubious advice that  
> even low-carb dieters should "carb-up" (I just googled this and  
> apparently doing so seriously inhibits fat burning).
>
> I read somewhere that exercise and extended ketosis both push up your  
> aerobic limit so that you can do more strenuous exercise while still  
> burning fat.


There's a study by Phinney of trained competition cyclists being put on 
a ketogenic diet for six weeks (I think).  During the initial three 
weeks, their performance was not as good as before they started, but 
then, after adaptation, they were as good or perhaps slightly better.  
Measurements showed improved fat utilization, but it took several weeks 
to show up.  Competitive cycling is an endurance sport, with frequent 
anaerobic bursts (like a lot of martial arts), so the body's glucose 
management is crucial.  A lot of people will tell you that you can't be 
in ketosis and compete in such sports, but Phinney's research shows they 
are dead wrong.  Their opinions are probably based on very short-term 
studies, before adaptation has occurred.  I think something similar 
explains the studies that purport to show that people in ketosis have 
impaired concentration and memory, but I don't have any data handy.

>> People who consume a lot of carbs are constantly putting their  
>> bodies in a state where all that incoming glucose must be dealt  
>> with.  So every cell that is capable of using glucose for fuel does  
>> so, and fat-burning metabolic pathways are downregulated.  Since  
>> insulin is the hormone for putting away sugar--either into glycogen  
>> storage, or into cells for burning, or into fat stores--it is  
>> constantly "working" in a high-carb environment.  And the result is  
>> often insulin resistance, a kind of overuse syndrome.
>
>
> That's interesting.  It suggests that diabetics are not necessarily  
> better on a high-carb diet even when it restricts food to a short  
> period every day (ie warrior-style high-carb) because they are still  
> keeping their insulin levels higher than necessary.

Type 2 diabetics will always have a difficult times disposing of all 
that glucose; that's the very essence of the disease.  The insulin 
resistance means that even though the pancreas is putting out plenty of 
insulin, the insulin receptors on the cells are not working well.  So BG 
doesn't go down as fast as it should, and the pancreas puts out more 
insulin, because it "thinks" there isn't enough in circulation.  And 
unfortunately the insulin also acts as a trigger for other metabolic 
processes, so having an overabundance of it throws a lot of things off 
balance.  This is why I believe that insulin control is *the* most 
important dietary goal.  I think the studies on intermittent fasting are 
very encouraging in connection with this.

Of course, you want insulin for other purposes too, such as general 
anabolic processes.  It's needed to get amino acids into cells for 
muscle building.  That's why some type 1 diabetics are very gaunt and 
unable to build muscle.

> There's only one other thing I'm curious about now.  From what I've  
> read, fructose does not raise blood sugar, or need insulin to be used  
> for energy.  I also believe it is easily converted into fat in the  
> liver.  Is this the case?  If the above is true then presumably you  
> can eat a lot of fruit and still return to ketosis quite happily  
> after, without going through a glycogen-depleted state.


First, keep in mind that fruits contain a blend of sugars, one of which 
is fructose.  So, depending on the fruit, you'll get glucose and sucrose 
as well.  And sucrose (table sugar) is a disaccharide that is half 
glucose and half fructose.  The proportions of sugars vary among 
different fruits.

Fructose is readily converted to triglyceride, so consuming a lot will 
push TG levels up.  But yes, fruit won't necessarily kick you out of 
ketosis as fast, if it's your goal to stay in ketosis.

Todd Moody
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