Although I'm guilty of scales watching too, weight is actually a rather poor measure of progress.
Most people's weight bounces around all over the place, and only exhibits a trend over a long span of time - say, 6 months. My weight can fluctuate a lot, for various reasons - some of them quite subtle. For example, I'll often be quite dehydrated after an Audax. This is not because I've not drunk enough during the event - but because my Glycogen level is low, and each 1g of Glycogen is bound to about 4g of water in the muscles. This can lead to a lower weight reading.
Another one is gut transit. If I reduce what I eat as part of a weight loss drive, then my gut transit slows a lot, and I can end up carrying rather a lot of... erm... "extra" around. This is despite eating a lot of fibre, and drinking water 'til I pee like a horse. It's just the way I am.
So - my Message of the Day - we need to try not to obsess about a few pounds/Kgs here or there.