Should I trust MFP's calorie burn calculations?

Always go with the lower number! And if you can, purchase a heart rate monitor.

So I spent 40 minutes on the elliptical this morning. The machine said I burnt 402 cals, but when I logged it into MFP it said I burned 647.

I'm just over 240lbs at the moment, and the the few times I did hold still for the handlebars, my heart rate reading was around 150-160 ( I just spend the last 3 months recovering from surgery and am crazy out of shape.) If i had to guess, I'd say my speed averaged around 3.6

How accurate have MFP's calculations been for you? I kind of want to go with the lower number to be safe.

http://www.shapesense.com/fitness-exercise/calculators/heart-rate-based-calorie-burn-calculator.aspx

Plug in your details there and compare. Machines in gyms are notoriously low at figuring it out.

MFP is notoriously high.

Get a heart rate monitor. They are motivating and you know exactly how many calories you have burnt.

Nope, I don't trust MFPs burn numbers they're always on the high side.
I use an online treadmill calculator and another calories burned one for other cardio activities where it allows me to enter my gender, height, weight, minutes exercised, and age.
Even then I low ball the calories burned number I enter on MFP just to be on the safe side.

no, not at all.

I've found MFP to be consistently high, but how high depends on the activity. For stationary bike riding it is off by a factor of 2. For snorkeling is is off by a factor of 3. If you want to get a real feel for the calories you burn, invest in a heart rate monitor.

Without an HRM I would recommend eating only 1/2 to 2/3 of your exercise calories back.

Fitbit is great but I don't use it for the gym, just day to day to see how much/little I move (desk jobs are not good for weight loss!)
A HRM is the best best for gym sessions (IMO)

I have a HRM, and always compare it to MFPs figures after running. I have been pleasantly surprised at how closely my HRM and MFPs figures correspond for running. This is for running only. I would not trust MFP figures for anything else. Actually, I don't even trust my HRM for anything besides running, because I think that's what they (HRMs) are most accurate for.

I have lately started to use a MET calculation for other activities (e.g. squash, strength training). I got this from the New Rules of Lifting for Women. The trouble is, you have to find a good MET table that lists a lot of activities to find the MET value for your activity. I found a pretty good list here: http://www.topendsports.com/weight-loss/energy-met.htm

The calculation is as follows:

Total cals burned = duration in minutes x (MET x 3.5 x weight in kg / 200)

So, for running, it gives a MET value of 10 for running at 10 minute mile pace, so for my long run this morning we have:

67 mins x (10 x 3.5 x 50kg / 200) = 586.25 cals

For comparison, my HRM said 582 cals

And MFP said 565 cals.

Don't you love when a few different methods of calculation arrive at similar conclusions?

For squash, the list gives a MET value range of 7-12, so I usually use 8 to get a conservative estimate of my calorie burn. I might use a higher MET value if I had a particularly hard game, but I probably wouldn't use higher than 9, because I don't think I work as hard in a game of squash as on a run. So, the calculation for squash is:

35 mins x (8 x 3.5 x 50kg / 200) = 245 cals

My HRM gave me 265 cals for a 36 minute game, which is pretty close to the MET calculation, although, as I said, I don't trust the HRM for anything besides running.

MFP gives 354 cals (big difference to my mind), which is what I would get if I used a MET value between 11 and 12. This is at the top of the MET value range for squash, and so I don't use MFPs estimate for squash.

I don't know if this was helpful or not, but it's quite interesting to me at the moment, as I want to get the most accurate calorie burn estimates I can.

Edited to lol @ Hilts

I don't eat my exercise calories so I just log and keep it moving!