What you're describing sounds more fluid related than carb/calorie
related. Did you increase fluids to compensate for your donation? It
probably wouldn't hurt to carb up a little before donating, but more
importantly, fluid load before and after, that's what DH and I find works
best.
You may also want to see your PCP and get a Hemoglobin and Hematocrit
done, just to get an idea of where you stand before your next donation.

Sas
154/138/130 (highest weight 164)

John
237/193/180
lc since 9/12/03

writes:

What did they tell you about your iron?  My SO donated as often as allowed when
he was overweight, but after losing 65 pounds he keeps coming in as slightly
anemic and they won't let him donate any more.  Yet his doctor says his iron
levels are fine.  The other thing is, has your blood pressure changed?  People
with low blood pressure often feel a bit dizzy when they get up quickly.  And
one of the things Dr. Atkins was emphatic about in his book is that a low-carb
diet will cause blood pressure to drop.  It all might be worth discussing with
your doctor next time you see him/her.

Daria
166/148/140
sugar-free since 2/1/04
low-carb since 2/17/04

Joe,
I donate blood and plasma regularly and haven't had that problem while on
low-carb.
I did after donating plasma one time, but that was when I was over 300
pounds and wasn't on low-carb at all.

One thing that has changed; I can't donate as much plasma as I used to be
able to; they go by body weight to determine how much you can donate at a
time.

Mark.

Many people get dizzy when they stand up quickly.  It's basically a
sign that you have an instance of low blood pressure (from the quick
standing, drawing blood away from the brain) that the body couldn't
quickly compensate for.

Now, having donated a pint of blood you will tend to have lower blood
pressure until your body replaces the fluid levels in your
bloodstream.  This can take a day or two, even if you load up your
stomach with fluids after donating.  It varies a bit from person to
person.

Since you have lost 30 pounds, it's quite likely that your body is
already running a slightly lower BP than it had been used to 6 months
ago (generally a good thing, of course).  When you add the blood
donation you dropped it some more - and when you suddenly stood up,
you dropped it enough (in your head) that it couldn't =immediately=
compensate.

Most healthy people experience it at some time or another, whether
low-carbing or not, having donated blood or not.  It's generally
nothing to worry about.  

As for the lack of bruises - perhaps you had more skilled nurses
inserting the needle this time, or perhaps you used to be deficient in
vitamin K on your old diet and now are getting enough.  Since you seem
to indicate that a bruise was common for you before when donating, I
suspect that the diet may be at work here.  I know that I'm eating
more broccoli on LC, for example.  Good source of Vit K.  Also
brussell sprouts, cabbage, kale, beef liver, green tea, cheese,
spinach and several other foods that are found on most LC diets.

Having donated over 100 pints myself, I found "after-effects" for
myself to be very rare - and bruising pretty much only happened when
they were quite obviously having a difficult time with the needle.
But people with low levels of vitamin K bruise much more easily.