Weight fluctuations are commonly due to the three reasons. They were
•The primary factor is water retention, which is caused by drinking very less water.
•Second factor is Glycogen stores, which must be reduced to lose weight.
•Third factor is the amount you’ve eaten. The calories that you burnt must be greater than intake calories.
It's not unusual for weight to fluctuate within a few pounds, depending what you ate, when you ate, when you went to the bathroom, how much you exercised, whether or not you are retaining fluid, etc.