Is it normal to lose about 3-4 lbs in a matter of three days?

I started to cut out the bad and put in the good about 3 days ago. On the first two days, I stepped on my scale and it gave me the same reading both times under the same conditions (naked, after first urination of the day, scale in the same exact spot as the day before). However, I'm curious about whats going on since I've lost 3.4 lbs in just the past three days. I don't think it's my scale since the first two days were consistent. Is it likely water weight? Or should I doubt my scale? Thanks for your help.