I never, never, never, lose any weight at period time!! (Apart from this month as I was doing the "soup diet" right over that time of the month... silly me!)
It's a fluid retention thing for sure. I get it quite badly sometimes. Also, my bowel movements are far less at that time, so all the stored crap adds to the weight as well
Here's some things that really help for me:
1. Herbal Diuretics (I take the one by Thompson's)
2. Laxatives, if really needed....
3. The best thing that I have found ever.... VITEX. It's a chinese herb of some kind I believe. Don't get it in the liquid form though as it tastes absolutely disgusting, no joke. The tablets are the way to go! I found that it stops most of the PMS symptoms, fluid retention included. This month I had virtually no symtoms at all, but a couple of months back, I didn't take the Vitex for the whole month, and I had every symptom under the sun! I was a horrible dragon lady
A good shopping site for all this stuff is http://www.completehealth.com.au
. They have a good range, good customer service and deliver really quickly.
I'd say to wait until a good few days after your period before you can get a good reading on the scales
Oh and the hungries can be a problem. I have heard that, because your metabolism is raised at that time, you can eat an extra 600kJ. So try to limit it to just a small extra snack.