Garmin and Fitbit discrepancy - running

tiny_clanger
tiny_clanger Posts: 301 Member
in Fitness and Exercise
Hi all,

Just looking for some advice really.

I use a Garmin for pacing and timing during runs and a fitbit for general stepcounting. I've got negative adjustments enabled in MFP.

Recently, as I've upped my long runs to 10K+ and my pace has improved, Garmin has been giving me 800+ exercise calories for each run. However, fitbit tends to deduct 1-200 calories from this, as it thinks I've not been that active. It tends to put my daily calories at 700 which, given that includes all my non-running exercise, seems to be quite a bit different from Garmin's run only calculation.

Which one do I trust? :) Is it worth turning negative calories off?

Thanks

Replies

  • sijomial
    sijomial Posts: 19,809 Member
    Which is closer to the formula?
    Net running calories = (Body weight in pounds) x (0.63) x (Distance in miles)

    That would be the one I would go with.
  • tiny_clanger
    tiny_clanger Posts: 301 Member
    Ok - thanks. That comes out much closer to Garmin than Fitbit (probably because Garmin use that formula). Maybe I'll switch off negative adjustments and see how I get on.

    I still don't understand why fitbit is so much lower, after all, Fitbit gets to count the warm up and cool down (at least 1000 steps each) as well as the actual run...

    Maybe it's just not that great at longer runs. It is spot on for 5K
  • litsy3
    litsy3 Posts: 783 Member
    Does fitbit just assume your steps are walking steps? You don't burn as many calories walking as running.
  • omma_to_3
    omma_to_3 Posts: 3,265 Member
    Basically, FitBit is adjusting your daily calories, including your run, and the Garmin is calculating just run calories. So, your FitBit is likely subtracting calories because it thinks you weren't active enough the rest of the day (basically using some of your run calories to make up for less active times of the day). I disabled negative adjustment because of this reason. Also, I know my BMR/RMR from lab testing and the FitBit assumes my number is about 10% lower than it really is.

    I've found the Garmin calorie calculation to be very good and very close to what I expect for my runs.
  • tiny_clanger
    tiny_clanger Posts: 301 Member
    Ahh - that's probably it! I'm working from home at the moment, so not very active when I'm not running!

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