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Calories burnt

Andrian
over 6 years ago

Hello!

Yesterday I had a normal day doing nothing special and i decided to test how many calories my watch (Fenix 5X) will detect while using the activity "Walking" (with GPS off) all the day.

I was surprised that the total calories burnt that day turned out to be 3800. Usually during that kind of normal days the calories count without starting the above mentioned activity "Walking" would have been 2500.

I wonder what could have caused this big difference?

Isn't the watch smart enough to calculate whether I am walking or not even when the walking activity is still running?

  • Former Member
    0 Former Member over 6 years ago in reply to Former Member

    Thanks for the link. Hopefully now we can get past this nonsense about calories burned from charts and exercise types and not the physical effort put forth by the individual. 

  • 0 over 6 years ago in reply to Former Member

    I sure wish that Garmin and/or Firstbeat documented this better.  Even if they don't give the specific algorithms, they could at least tell us what the inputs are.  I have read extensively in the Firstbeat site and their white papers, but still can only guess at how calories are computed.

    I do believe that heart rate is an important input to calories.  I highly doubt that they are doing a simple table lookup. But, as per the Firstbeat site, they also use "heart rate variability". I think when you are resting your heartbeat variability is very low but when exercising it becomes more variable, and they use this to compute calories.

    But, i have wondered if, given the exact same observed data, that is heart rate, heart rate variability, and all the person's personal profile data, will the computed calories be the same no matter the activity?  I cannot say for sure on that point. The watch also has an accelerometer, so i wonder if that could affect calorie computation.  Firstbeat does not mention using that data, though.

    Another thing i have wondered about is the User Profile Setting "Activity Class" which you can set from 0 to 10. Given the same recorded data, will the computed calories be more or less depending on what you set for activity class?

    Would sure be nice if somebody had some authoritative answers to these questions.

  • Former Member
    0 Former Member over 6 years ago in reply to TomCon
    TomCon said:
    User Profile Setting "Activity Class" which you can set from 0 to 10. Given the same recorded data, will the computed calories be more or less depending on what you set for activity class?

    I can't give you a definitive answer, but years ago I was using a program from This is Ant+ that looked at all the settings in my FR235. I noticed changing your activity class changed the amount of your BMR calories. I don't even know if the FR235 was using Firstbeat metrics back then. 

  • 0 over 5 years ago in reply to TomCon

    Hey did you ever get any farther with this? I've just purchased a Fenix 5 Plus after owning a Fitbit Charge 2 for ages and the calorie count on the Fenix is unrealistically low. Ie. 2 hour gyms session with HIIT followed by strength training suggesting I've only burned 500 calories whereas the FItbit reports near 1000. Macros are miles out now. Also saying I'm only burning 100-200 calories on top my BMR when I'm doing labour intensive work all day but not recording an activity....

    - Do the Fenix watches monitor heart rate and calculate calories burned throughout the entire day or do you have to have activate and activity for it to record and change the calories burned?

    - Do I need a heart rate strap to utilize the Firstbeat technology or is it an automatic function of the watch and uses wrist based heart rate information when a strap is not worn?

    - Is there a setting somewhere to turn Firstbeat on?

    Seems absurd that such an expensive watch would lack such a basic feature...