Calories and weight loss plateau

Question
I am 5'2" and 139 pounds. My highest weight was 165 lbs. I have largely maintained my weight at 140 or so for the last four years and cannot seem to lose the last 15 to 20 pounds to be at a healthy weight of 120 to 125 (I have a medium frame).

After poking around the net recently I have become confused about what people are calling "net intake" of calories. Calculators have informed me that in order to maintain my weight I need around 1500 (w/out activity) give or take. In order to create one pound a week deficit, I have been eating 1200 to 1400 calories per day and burning 200 to 400 calories through exercise most days (4 times per week, including a variety of cardio exercises and some work with free weights). This generally puts my "net" calories at 1000 (on a good day), which is the 500 calorie deficit I think I need to lose a pound a week.

Should be eating more, to make up for the calories I burn past 1200 with exercise, in order to lose the weight? This is confusing to me, because if I eat back the calories I exercise away, that means I will not be able to reach the 3500 calorie deficit per week since my maintenance is 1500.

Please help, I am beyond frustrated at this point.

Answer
Dear Moriah,

On the one hand, the calorie business is very tricky and seems to be beyond simple computations. On the other hand, it's answered quite a few times. Why wouldn't you just read about different aspects of it in the following articles:

Aren't All Calories Equal?
http://atkinszone.com/2008/03/calorie-calorie-calorie.html

3500 Calories To Lose A Pound: Is This Formula All Wrong?
http://atkinszone.com/2008/03/3500-calories-to-lose-pound.html

Aren't All Calories Equal?
http://atkinszone.com/2008/03/calorie-calorie-calorie.html

Is it possible to make calories less fattening?

Calorie Controversies
http://atkinszone.com/2008/03/calorie-controversies.html

Calories and Low Carb Diets
http://bantadiet.com/banta/?page_id=42

Exercise increases my calorie intake
http://en.allexperts.com/q/Nutrition-Dieting-939/2008/3/Exercise-increases-calor...

1500 calories a day, no weight loss
http://en.allexperts.com/q/Nutrition-Dieting-939/2008/2/1500-calories-day-weight...

If it's not enough (after you read) please follow up this question for more information, OK?

Tanya Zilberter

1. Prev:body fat loss
2. Next:Zinc deficiency