FB and others- I too weigh daily and see those fluctuations. Yesterday I was up 1.5, probably due to sore muscles and pizza. Even though I ate within my calories, sodium causes water retention. Also, incase you've never heard this. When muscles are worked hard, and they are sore, they require water to repair them, hence a slight gain.
I had been stalled most of Nov. and all of Dec. Got back to measuring and logging every morsel and have started losing again. It really is work, but well worth it.
SW- 200.6
CW- 197.2 (-3.4)
GW- 195.6
Someone is bound to bring this one home soon.

Still the same today as yesterday (-0.6 from SW).