Fredrik Murman wrote:

>Todd Moody <[log in to unmask]> wrote:
>
>
>
>>When you eat lots of carbs, your glycogen reserves are
>>almost always full, so incoming carbohydrate can't be deposited in
>>them.  Therefore a great deal of it must be converted to fat, and the
>>fat into which it is converted is almost all saturated. 98% palmitic
>>acid, in fact.
>>
>>
>
>It would be interesting to know how much palmitic acid is produced from say
>100 g of carbohydrate. Any idea?
>
>

I can only guesstimate.  The energy yield of 100g is about 400 kcal
(actually a bit more).  Since all fats are about 9 kcal/g, that means
that the *most* palmitic acid you could produce from 100g of
carbohydrate would be 400/9= 44g.  But in reality it would be less,
because some of that incoming carb would be immediately used by cells,
and some would stay in circulation in the blood for a while.  Your body
has two reservoirs for glucose: the glycogen stores and the blood.  As a
rough estimate, the circulatory system holds about 5 liters, or 50
deciliters of blood.  Suppose your fasting blood glucose is 80 mg/dl.
Then you eat 100g of carbohydrate, which is converted to glucose (I'm
ignoring fructose and other monosaccharides, to keep it simple).  That's
100,000 mg.  If all of that were to go into circulation in your 50 dl of
blood, it would represent an additional 2000 mg/dl, resulting in a BG of
2080 mg/dl, which I believe would kill you outright.  Of course, it all
doesn't go into circulation immediately, but nevertheless your body must
scramble to deal with it, so every cell that *can* use glucose will
attempt to do so, and if there is any room in the liver or muscles to
convert some to glycogen, that will happen too.  And the rest will
speedily be converted to palmitic acid, to get the BG back down to normal.

>Excuse my ignorance. Can body store dietary saturated fatty acids, or are
>they just floating around in the blood stream?
>
>
Both.  They float around in the blood stream as free fatty acids up to a
certain concentration, but since they *are* acids, they acidify the
blood, so to maintain  normal pH they must also be taken out of the
bloodstream.  This happens as they are used by cells for energy, and
also by being stored in fat cells.  Fat cells fill up with fats, and
that's where they get it.  And as I mentioned in the other post, a
significant amount get converted to MUFA.  The marbling in meat and my
love handles are all example of stored saturated (and monounsaturated)
fatty acids.

Todd Moody
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