I weighed 187.6 lbs last night, and 185.4 lbs this morning, about 10 hours later.
If you wanna get a reasonably accurate weigh-in, do it first thing in the morning, after you use the toilet, before you drink or eat anything (as to avoid weighing the undigested food, and water weight). And of course, do it naked.
even then, its normal for weight to fluctuate several pounds from day to day due to water intake, constipation (or the opposite...mud butt), too much sodium intake, or even a 'loading phase' of creatine (extra water retention).
hence I only weigh in once every week, sometimes only every two weeks if my diet has been rock solid.
plus, without a good bodyfat test, you don't really know what kind of weight it is you're losing or gaining. water, fat, muscle?