I started TOM last Thursday, which was my weigh-in day at TOPS and of course I was up a 1 1/2 pounds!
It is totally normal for me to gain 3 to 5 lbs right before and during the first couple of days. Today, I'm down the 1 1/2 plus 3 more.
I told my doctor about it and he gave me some water pills which do seem to help me. I only take them right before TOM and for a few days afterwards.