I try to be very aware of everything I have ingested and weigh myself often. I have an even food and liquid intake, and when I see a high (or low) blip, I can usually rationalize why I'm having that blip:
--oh, I ate wendy's chili and it has a lot of sodium, I'm retaining water...
--I need to poo.

--TOM
--I've been sick and I'm dehydrated
--It's first thing in the AM
--I exercised a lot
It helps me be more aware of my body, what I'm eating, the cycles my body is on, the ways different foods affect my systems, etc.