How did I gain 4 lbs overnight??

I’ve been IF 18:6 for a month and been losing 1 lbs per week. Yesterday I ate a little more than normal and after my end time. Weighed myself this morning and I’m up 3 lbs? I don’t understand how and why? I drink my 6/8 glasses of water. I Need insight pls via /r/intermittentfasting https://ift.tt/kFYsnAg https://ift.tt/vUtwe5G