TDEE versus FML

42# to lose? I'd stick with 1500 every day for a while, exercise or no. That way you'll get used to some healthy new habits.

Yes I started just above 170 and I'm trying to get back to 130. 140 is probably more realistic for me but one can dream. I'm 5'6 and I work at a desk job and run 3-5 times a week for 40 mins. Am I calculating something wrong?

This might get a little rambly, so I hope it makes sense.

The MFP site takes your stats, amount you want to lose, and activity level indicator and figures a calorie goal for you without including your exercise. If you tell it you want to lose 2 pounds a week it will lop off 1000 calories from your calculated maintenance, not dropping below a 1200 calorie threshold. Thus, setting an aggressive goal gives you a lower goal. The site also expects you to log any exercise and adds calories to your goal as you earn them.

The TDEE calculator, on the other hand, already includes exercise (you've calculated with and without, I see) but instead of taking a flat number of calories off you're taking a percentage of calories off (I assume 20%). A 1900 calorie TDEE - 1000 calories in order to lose 2 pounds a week (per MFP's calculations) would have you at 900 calories, an unsafe level. At 1500 calories you're at a much safer level (better hormone regulation, less lean muscle loss, better gym performance, etc) but you'll be set to lose about a pound a week instead of two pounds. That's why you're seeing such a big difference in numbers.

Yes I started just above 170 and I'm trying to get back to 130. 140 is probably more realistic for me but one can dream. I'm 5'6 and I work at a desk job and run 3-5 times a week for 40 mins. Am I calculating something wrong?

This might get a little rambly, so I hope it makes sense.

The MFP site takes your stats, amount you want to lose, and activity level indicator and figures a calorie goal for you without including your exercise. If you tell it you want to lose 2 pounds a week it will lop off 1000 calories from your calculated maintenance, not dropping below a 1200 calorie threshold. Thus, setting an aggressive goal gives you a lower goal. The site also expects you to log any exercise and adds calories to your goal as you earn them.

The TDEE calculator, on the other hand, already includes exercise (you've calculated with and without, I see) but instead of taking a flat number of calories off you're taking a percentage of calories off (I assume 20%). A 1900 calorie TDEE - 1000 calories in order to lose 2 pounds a week (per MFP's calculations) would have you at 900 calories, an unsafe level. At 1500 calories you're at a much safer level (better hormone regulation, less lean muscle loss, better gym performance, etc) but you'll be set to lose about a pound a week instead of two pounds. That's why you're seeing such a big difference in numbers.

Ok thanks. So since I've calculated the TDEE I should adjust my goal to 1500 a day and NOT log excercise right?

Assuming you're using your TDEE calculated with exercise then you're correct, you don't need to worry about extra exercise calories because they're already built into your goal with this method.