Todd said:

This seems to be fairly common among people on lowcarb diets,
judging from messages I've read at http://eatprotein.com and
elsewhere.  The "word on the street" is that the diet invigorates
the follicles, stimulating new hair growth, but before that
happens you shed the existing brittle hair.  I experienced
something similar, noting the thinning of my hair, which I
attributed to middle age.  Eventually the condition reversed
itself.  My hair is now thicker and less brittle than it was two
years ago.  But it took time to happen.  This is all anecdotal
and I have no idea if it has any scientific validity, but I've
heard this sort of thing a lot.
+++++++++

It's funny, I've been eating low-carb/paleo-ish since April 2000 (following
35 years of SAD); I haven't noticed any hair loss; in fact, my hair (which
was always in decent condition) seems even healthier to me now, and my
nails are stronger and less prone to chipping and breaking. But just a few
days ago, my hairstylist was cutting my hair and she told me that she
thinks I've lost a lot of hair. I'm not sure what she means by a lot; she
has a bit of a tendency to overstate things. But I was surprised to hear it
all. I honestly have not noticed losing any more hair than is normal; in
fact, I kind of thought it had decreased. I guess I'll keep an eye on it.

Deborah