Elizabeth Miller wrote:

>Even if we never eat a single
>molecule of saturated fat, everyday our body will metabolize some from our
>fat stores. I can't for an instant believe that we have evolved to store fat
>to provide energy and materials to us that is harmful. It just doesn't
>compute!!!
>
>

Regardless of whether Cordain is right or wrong to be concerned about
dietary saturated fats, the logic of your position here has to be
questioned.  It is also true that even if we don't eat a molecule of
glucose, our bodies will make some every day.  Does it follow from that
fact that eating glucose in whatever amount can't be harmful?  I don't
think so.  The glucose you make is made *on demand* in amounts
proportional to that demand; the same cannot be said about the glucose
you may eat.  The same point applies to the palmitic acid you make from
glucose: it is released from adipocytes *on demand*, which is not true
of the palmitic acid you eat.

What makes these fat issues so confusing is that even the term
"saturated fat" is too blunt an instrument.  The saturated fats are

4:0     butyric
6:0     caproic
8:0     caprylic
10:0    capric
12:0    lauric
14:0    myristic
16:0    palmitic
18:0    stearic

Of these, the only ones that I am aware of that are possibly
problematic, from a health standpoint, are myristic and palmitic acid.
 When we convert glucose to fat, something like 98% of it is palmitic.
 Animal fat deposits have different amount of these fats.  Stearic acid,
also found in chocolate (and candles and crayons) is the hardest fat,
and it predominates in the fat deposits around organs (like suet), since
it apparently has a protective structural role as well as serving as an
energy supply.  In addition, some palmitic acid is also converted to
MUFA, which is why beef fat is a little more than half MUFA.

What we need is more information about the metabolic effects of these
various fats, and especially their effects on insulin sensitivity.  Ron
Rosedale takes a "follow the glucose" approach, and sees excess palmitic
acid as just another problem that too much glucose causes.  In
particular, he thinks that if we are trying to burn body fat, which has
a lot of palmitic acid, and at the same time eating a lot of it, we are
simply getting too much.  This is why he recommends limiting saturated
fat *during weight loss* -- while one is burning one's own palmitic
acid.  This makes some sense from a paleo angle.  After all, we store
excess fat as an energy store for when we need it.  "When we need it"
would certainly be times when dietary fat is scarce -- so paleo man
would not normally be burning up large amount of  body fat at the same
time as eating lots of animal fat -- right?

Todd Moody
[log in to unmask]