Replacing Calories?

If, for example, you need 2000 calories to maintain your current weight and you have told MFP that you want to lose 1 pound a week, it might recommend 1700 calories per day (I'm making up numbers). If you eat that 1700 you will lose about 1 pound a week. If you work out and burn 300, you would have taken in 1400 for the day. You can then eat the additional 300 and you will be be at 1700, right at your recommended number.

So I dont necessarily have to replace the calories if I dont want to? It simply a recommendation from mfp?

no you don't have to but that being said if your calorie goal is 1200 (lowest recommended for a woman) and burn 500...you should eat them back to fuel your workouts.

But MFP has given you a calorie goal to lose the desired amount of weight you want...the exercise allows you to eat more food..who wouldn't want that?

As long as you are netting 1200 for a woman, 1800 for a man and fueling your workouts you are eating enough.

remember tho if you are losing fast chances are you are losing fat and muscle esp if you aren't eating enough protien and getting enough protien can be hard on a low calorie diet.

MFP calculates the amount of calories you would need not including exercise. This is so you would lose weight if you were not able to exercise. When you do exercise, you need more fuel for that.

Suppose you had just enough gas in your car to go to work and back. But then you wanted to go to some special event tonight and it is 50 miles round trip, you need to put more gas in your car, right? Eating the base calories MFP gives you is like the gas to go back and forth to work. Eating more when you exercise is like the additional gas you need to get anywhere else.

That said, many people say that the amount of calories MFP gives you for exercise is inflated. Unless you are using a heart rate monitor for a better estimate, some only eat half or 3/4 of the additional calories MFP gives you.