I think you might have misunderstood something.
There are, IMO, 4 numbers you need to know to lose weight.
1. What your BMR is: BMR Calculator
FitDay does this calculation for you too - more or less.
2. How many calories you burn from activities - FitDay is a huge help here.
3. How many calories you have eaten in a day - be careful of serving size - because almost everyone under estimates the amount they eat - at least at first. FitDay is also a huge help here.
4. There are about 3500 calories in a pound of body fat.
So, to lose weight - eat about 1000 calories less then you burn (BMR + activity).
If you go too low - your body will try to conserve calories - so make sure you stay above about 1200-1500 cal/day.
If you go too high (over BMR + activity) you will gain weight.
If you stay at a deficit of about 1000 cal/day you will lose about a pound every 3 days or 2 pounds a week which is generally considered a safe rate to lose weight.
You'll probably lose a lot more the first couple weeks, but bounce around a bunch. I weigh daily and expect about a 3-5 pound +- daily difference, but if you are prone to being bothered by "not making progress" you might only weigh once a week so that differences in hydration and um, intestinal bulk don't make you think you are failing.
The FitDay charts are great to see the whole picture and see the general trend downward.
(But we are kind of in the wrong thread for this conversation)