How often do you weigh yourself? I find most people either weigh themselves everyday (sometimes multiple times) or they don't at all. Because I'm a dietitian and interested in seeing what happens with weight from day to day, I weigh myself about five times a week, or every time I go to the gym. Doing so has led me to believe that we all should establish a weight goal that considers a range, rather than one finite weight.
My weight fluctuates several pounds in a given week, but my weight range doesn't change. I have picked an upper limit weight that I am happy with, that feels good and is a healthy weight for my height. When I hit that upper limit however, I know that I need to pay more attention, because I don't want to go higher. It gives me motivation to keep an eye on things, and then I'm able to stay within the range rather than going above.
Oftentimes, the fluctuation in the scale is due to a salty meal, hormones, etc. Last Monday I was over my upper limit. That's what three family birthdays, spring break and Easter will do to a girl. However, that Tuesday (the next day), I was down 2 pounds and back within my goal weight range. Did I really lose two pounds overnight? Not likely. The other nice thing about a weight "range" goal is that it allows for those annoying fluctuations of a couple pounds that aren't true weight gain/loss, without making you crazy trying to figure out what you did "wrong" to gain weight. I have a client who started using the weight range idea and realized her weight could fluctuate up to 5 pounds in a day or two, but she stayed in the weight range goal, so she didn't stress about it. If weight loss is your goal, your weight range should ideally decline over time. As you lose weight, you can adjust the range.
Self monitoring is a key tool to use for weight loss. One way to self monitor is to keep a food log, another way is to record your weight weekly and watch the trend. That's also a good way to ignore the day-to-day fluctuations. Record one weekly weight, at the same time on the same day of the week, wearing about the same amount of clothing. One weight is just a blip on the graph, the trend is what's most important. If you record the weight weekly and see it trending up, it's time to monitor even more - set some goals, keep a food log and re-focus your workouts.
In the group weight loss class that I teach, a recent participant was frustrated with the fact that her weight wasn't changing. But, she told me she noticed that her clothes were fitting better, exercise was easier and she had more energy. To me, that's much more meaningful than the number on the scale. Try not to get too hung up on the scale but focus more on your effort to lead a healthier life. Feeling well and moving better are great things, regardless of what the scale says.