How to accurately monitor your weight
The key here is to weigh yourself at the same time (morning works best for most people), on the same scale and maybe only once or twice a week.
If you are ready to give up on the scale and would like other methods to assess changes in body size, you might want to consider one of the many methods for assessing body composition.
But just like the scale can fluctuate, so can the numbers from testing. Accuracy of body composition testing depends on the expertise of the person conducting the test and the method being used. If you choose to opt for this method, it's best to consult a health/fitness professional who has been trained in these skills.
Weight fluctuation is normal, but if the scale rises five or more pounds for longer than a day or two, chances are it's more than simply water weight and it's time to make some adjustments.