Jerebear saidWeighing yourself at night and weighing yourself again the next morning is absolutely completely nonsensical and is a great way to add needless stress to your life.
Only if you let it add stress.
I weigh several times a day for observation on how things affect my body's weight. I can tell you that sitting in the plane 4 hrs at a time - even drinking a bottle of water - I'll still lose about 3 lbs of water. That's a half gallon. Gotta rehydrate after every flight.
Then again, I use the body scale thing that records everything (BMI, bf, water weight, etc.) so I can see trends and graphs on the computer. The numbers mean nothing. The monthly trend means everything.
As long as you're approaching it from an observational point of view rather than expectational, you'll learn a lot about your body.