Learn how to ignore the ups and downs of weight fluctuation. Weigh yourself every day, and use a moving average to compute a trend line. Your weight may fluctuate by 5 or more pounds per day, and your true weight loss will be lost in this fluctuation. A moving trend line makes your loss/gain clear!
Do a Google search for "the hackers diet" to learn about moving trend lines.
The following site takes the effort out of computing the moving trend.