The disorders associated with Syndrome X are mainly caused by the 
effects of chronically elevated insulin.  That is, "syndrome X" refers 
to the effects, hyperinsulinemia is the cause.  The main cause of 
hyperinsulinemia is insulin resistance (IR).  The ultimate cause of IR 
is still debated, owing to the complexity of teasing out the precise 
causal mechanism.  For example, there's evidence that obesity causes or 
aggravates IR, and also evidence that IR causes obesity.  From a health 
perspective, there's no need to wait for these puzzles to be solved, 
because it's clear that the best thing to do is to attack obesity and IR.

I think this study, 
http://www.pubmedcentral.gov/articlerender.fcgi?tool=pmcentrez&artid=1368980 
is a good one, and deserves to be better known.  Why is it that studies 
like this one don't get featured on CNN?

A couple of things to note:  First, it's a proper lowcarb study.  Some 
studies that purport to study "reduced carbohydrate" diets actually use 
only very modest carb restriction, but this one limits carbs to 4% of 
calories in the lowcarb group.  Second, fat loss was about the same in 
the three diets studied (very lowcarb, very low-fat, and high 
unsaturated fat), although the lowcarb group lost a bit more.  It's 
interesting that there was more lean muscle loss on both the lowcarb and 
low-fat diets than on the unsaturated fat diet; I wouldn't have expected 
that.  It's also interesting that homocysteine increased only on the 
lowcarb diet.  And although there was a 7% increase in LDL cholesterol 
in the lowcarb group, which isn't surprising, there was an increase in 
HDL, which is contrary to often-heard claims that HDL can't be raised by 
diet.  The reduction in triglyceride on the lowcarb diet isn't 
surprising either.  But to me the most impressive result was the effect 
on fasting insulin, which dropped by 33% on the lowcarb diet, and wasn't 
budged at all on the low-fat diet.  That reduction in fasting insulin 
suggests, to my mind, a real reduction in IR that cannot be explained 
simply by fat loss, because fat loss was about the same in all three 
groups.  And for those (there are many) who insist that saturated fat 
*causes* IR, it's difficult to reconcile that claim with this result.

Todd Moody
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