I weigh myself every morning and can notice some fairly big weight fluctuations depending on what I eat/drink the day before. In general if I keep to my healthy diet/exercise it will go up or down ~300 grams. However if I have a cheat day (or 2) where I gain 1-3kg and then the following day I eat normally and do a ride I can see it go down by that same 1-3kg.
For a while I was also weighing myself before bed and then immediately after waking and using the washroom. I would see a difference of 800 - 1000 grams the following morning while I did that.