On Sat, 2 Dec 2000, R Bartlett wrote:

> Cortisol levels are higher in the morning because both exercise and sleep
> increase cortisol release from the adrenals.  Higher cortisol has the effect
> of mildly increasing insulin resistance.

This is a good argument against long-term ketogenic dieting.  The
reason why both exercise and sleep increase cortisol release is
that they both tend to cause a drop in blood sugar.  Exercise,
especially high-intensity exercise, does this by working the
fast-twitch muscle, which can only burn glucose.  Sleep does it
because we don't eat for an extended time.  When blood sugar
drops, cortisol is the hormone that is used to trigger the liver
to make glucose from protein -- gluconeogenesis.  Since ketosis
is, by definition, a state in which glucose is depleted much
faster than it is replenished by diet, it requires a more or less
continuous gluconeogenesis to keep blood sugar within normal
range, and this means that cortisol levels must be continuously
elevated to keep the gluconeogenesis going.

Todd Moody
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