I weigh once a week, and have only had a "gain" (1-2 pounds) 3 times in the last 13 months, only 2 of those times can I attribute to PMS/TOM. I guess I'm lucky because everything else about PMS is horrible for me. I have found that the times I have gained (except for last week which was not PMS but a really bad day) is when I go overload on salt. As long as I try to avoid salt and squeeze lots of lemon in my tea or water it REALLY helps with the bloat. Of course if you give into the cravings that go along with PMS/TOM then stop
and do other things like clean toilets or something.
Oh and if you know you are about to "start" don't weigh until around the 3rd day.