[tech/medical] What is it with walking calories and MFP/trackers?

PAV8888

The exrx calculator is MET based just like the Garmin and Fitbit trackers.

What exrx does is more explicitly separate net values.

However, the exrx net are not the same as MFP net.

Exrx net subtracts 1* BMR calories for your net value. MFP has assigned 1.25 to 1.8* BMR calories to the time slot, and you would only earn extra calories that you should consume when you move above that.

The trackers use MET values based on detection and interpretation of what they detect

When I had checked a while back, Fitbit would try to guess from heart rate and movement (accelerometer) data your per minute activity level and then average it over 5 minute segments.

Then it would assign an average MET value for the 5 minutes segment based on the type and "vigour" of activity it thought it had detected for the time period.

My personal impression was that this almost always was maybe a couple of more calories than it should, at least for me, but that Fitbit compensated by assigning 1.0 times BMR when there was no detection.

But sitting quietly in your chair working on a computer is not a 1.0 * BMR activity, it is actually at 1.3 times or so going from memory.

and for most people activity is the lesser part of the day's calories, with inactivity occupying substantially more time than activity.

I am not sure where that leaves us in terms of an exact caloric value for a specific exercise.

But I know that in general, if I have logged my food intake carefully, I have no real issue figuring out an approximate TDEE divergence from Fitbit's all day value for my personal levels of activity and mentally taking it into account.

This does not invalidate someone else's experience if after careful observation they find a much larger Divergence then what I have encountered