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Garmin's BMR Calculations

cbskillz
over 8 years ago
I think I might be having an issue with the BMR calculation, but I don't really know that much about how BMR calculates. Would someone please be able to provide some context for how it is calculated, or perhaps point me in the right direction? Would using the Garmin Index scale improve the BMR calculation (as opposed to a different product - I currently use a different product but if it would make practical sense to change over I'd consider it)?

My specific problem: after 8 months of successive weight loss (counting cals using MFP, exercise, healthy diet, etc) I'm starting to plateau. Last two weeks show zero weight loss. In the last three months I've upped my fitness considerably, so I should expect to see an increase in BMR, decrease in weight, with a healthy diet. I still am sitting about 22% BF, so not having the weight to lose is not the factor (29 y/o m). I'm a bit concerned that Garmin is over estimating my calories burned during activity and perhaps under estimating my BMR calc, which would throw off the whole calculation pretty dramatically. Using Fenix 3 HR to track it all. Activities are cycling, running, & swimming. Of course, could all just be a fluke or muscle increases outweighing the fat loss, but I'm a big data nerd and haven't seen this kind of pattern stick for this length of time. BF% has remained reasonably constant over the same two week period.

Any comments are appreciated. TIA.
  • 0 over 8 years ago
    BMR calculations in general uses things like your weight, height, age, and gender. The more you weigh for example, the higher your BMR. (it takes more calories for your body to do it's basic stuff).

    As your weight drops, so will your BMR. But it should be easier to get "active" calories.
  • Former Member
    0 Former Member over 8 years ago
    Hi,
    Garmin uses after the last mayor update the Mifflin St Jeor Equation:
    https://en.wikipedia.org/wiki/Basal_metabolic_rate

    here you can calculate your BMR
    http://www.calculator.net/calorie-calculator.html

    PS: MFP does not adapt automaticly to the changes of your BMR so you have to have it recalculate your goal on the website again (user profile)
  • 0 over 5 years ago in reply to Former Member

    Well 3 years(08.2019) later it seems it's more then that because If I enter the same data in the above calculator (age, weight, height....) for Miffin St Jeor Equ it gives another result then my garmin.

  • 0 over 4 years ago

    Issues you’re facing are correct. As you lose weight, the body becomes more efficient at rest - so you burn less calories when not exercising (likely also while exercising since you weigh less and are presumably in better shape). This is why sometimes a change in exercise regimen is helpful. If you were mostly running, add some other cardio. If you’re weight lifting change the types of exercises so your burning more calories BC you’re less efficient. 

  • 0 over 4 years ago in reply to Ivaylo Minkov
    Ivaylo Minkov said:
    Well 3 years(08.2019) later it seems it's more then that because If I enter the same data in the above calculator (age, weight, height....) for Miffin St Jeor Equ it gives another result then my garmin.

    Well, it is a years-old thread, but just for the reference - Garmin Connect does not use BMR (Basal Metabolic Rate), they use RMR (Resting Metabolic Rate) instead. It differs slightly from the BMR, so that is one of the reasons it does not match the BMR calculators. 

  • 0 over 3 years ago in reply to trux

    But if you multiple Mifflin St Jeor by 1.2 you get Garmin daily RMR. At least it was my experience with Fenix 3 HR.