Eating back calories

From what I've gathered if you've taken into account exercise when calculating how many calories you're supposed to eat then you should ignore MFP and not eat the calories back.

If you have read through how MFP is set up when you started your account, you would have noticed that MFP already creates a deficit for you, regardless of exercise. Which means that even if you don't exercise you will lose weight. When you exercise, you further increase that deficit, possibly to an unhealthy level. This is why MFP tells you to eat your exercise calories back. Think of food as fuel. Your body needs fuel.

I always eat back my calories burned!

MFP uses your NEAT to calculate your activity level...when you set your goals, your activity level should be set to a level that is appropriate without exercise. When you do this, exercise is extra and therefore MFP bumps your calorie goal up so that you still NET to your GOAL.

Failure to eat back your exercise calories may result in drastic under eating, particularly if you're at a very large calorie deficit (i.e. 1,200 calories). If your goal is 1,200 calories, you have about 800-1000 calorie deficit from your maintenance level of calories there...that's huge...when you exercise, you make that deficit even bigger which is unnecessary and potentially dangerous. Also, too large a deficit will lead to a metabolic stall...essentially your measly little calorie intake becomes your new maintenance level of calories...then you have to go to work re-booting your metabolism if you ever want to eat normally again...most people put on a few pounds in the re-boot process.