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
[log in to unmask]
|