myfitnesspal accurate for calories burned?

I ran a test for me to kind of calibrate myfitnesspal. I went 2 weeks without exercise and logged all my food. I came close to 2 lb weight loss at the prescribed deficit. When I added exercise at the calorie counts they gave I didn't come close. I've been tweaking down the calories given a little at a time until I see the results I want. Right now I remove 100 cal every 40 minutes of cardio. After all what do I care what the calorie number ends up I want the weight number down!

I posted this in a separate thread here that I started before I saw this one, but I'll put it here, too:

For the curious, I've done a few recent training runs wearing my Heart Rate Monitor, and my phone logging Runkeeper, and posting to MyFitnessPal afterwards. The routes were different, but very similar (pancake flat). I'm a 6'0" male that currently weighs 195 pounds.

Here are the numbers for calories burned:

Run #1 - 5.11 mile run, 50:51 time (9:57 min/mile pace), avg. HR was 151 BPM.
HRM = 804 kcal
Runkeeper = 783 kcal
MyFitnessPal = 770

Very consistent numbers.

Run #2 - 5.04 mile run, 49:45 time (9:53 min/mile pace), avg. HR was 145 BPM.
HRM = 695
Runkeeper = 772
MyFitnessPal = 740

A little more variance, but still pretty close.

Just thought I would share for the inquisitive minds here on BT. :-)

I find that even HRMs can overestimate calories as well. For example, here are numbers from my 2 hr trainer ride this morning. Keep in mind that I only averaged a HR of 125, so this wasn't done at high intensity at all:

MFP (logged it as Bicycling, 12-14 mph, moderate): 969 calories
Garmin 910xt: 1075 calories

While those two numbers are close, I know that they're both way higher than they should be. Oddly, I also have another Garmin device just for cycling, and that one will give me lower, and likely more accurate, values for calories burned. From that, I figure I actually average 300-400 calories per hour, depending on intensity. Since this workout was low, I estimated 600 calories.

Since I've gotten used to estimating my calorie burn (I also estimate approximately 500 calories/hour for running and 300-400 for swimming), I just don't pay attention to the readouts from elsewhere. Just thought I'd mention it to point out that even using a HRM may not be accurate, depending on the device it's linked to.