I have a theory. It's that when someone initially starts to lose weight, their metabolism is slow. Therefore, they begin to exercise and they eat fewer calories to lose weight. As time goes on with this program, the increased fitness and consistent exercise means increased metabolism. But the person who started out with lower calories is now afraid to increase them. Their "proof" that they should not is that if they do eat, say, 1500 calories, they see a weight gain the next day.
I got into a long plateau. How it went for me was that I would stay on my low-cal plan for 4 or 5 days, and then I would get so hungry that I would end up eating more like 1800 or 2000 one day. My weight just went up and down, up and down.
I joined a new gym and started working with a trainer. The trainer said that I should be eating much more than I was. At first I just laughed--like this trainer didn't know anything about formerly obese people. But I kept looking around at calculators, and they all said about the same thing.
I thought, what if my metabolism is no longer so slow...
So, filled with trepidation,

I raised my calories to 1500 ave. per day, as my FitDay calculator told me to do. I set my burn for moderately active instead of sedentary. I set my goals for 4-week periods these days and aim for 3 pounds in 4 weeks. Of course, I have kept going to the gym and working out.
The result is that I'm down 5 pounds in 6 weeks, which is slow, but it's real. And I do not feel out-of-control hungry. In fact, it's been hard for me to get up to 1500 because I've gotten so used to eating less.
So--I'd say, if you're going to try it, try at least 2 weeks and maybe 4--and don't freak out if the scale goes up at first. Just slog it out for the alloted period of time.
Jay