This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Active calories numbers are way too low

I rode my bike outside yesterday for 2+ hours at 16.4 mph and Garmin says that I burned only 802 active calories for the entire day.  I weigh 175 pounds, so the number should have been closer to 1600.  How is Garmin calculating this number?

  • How is Garmin calculating this number?

    It uses algorithms from Firstbeat Technologies, based on the Heart Rate Variability. There is a white paper describing it in details:

    https://www.firstbeat.com/wp-content/uploads/2015/10/white_paper_energy_expenditure_estimation.pdf

    I weigh 175 pounds, so the number should have been closer to 1600.

    Possible, but that's including the RMR (Resting Metabolic Rate). Active Calories are stripped off of the RMR.

  • Thanks for the reply.  Their algorithm using heart rate only is apparently not very accurate in my case.  I have been tracking my calories consumed and burned everyday for almost two years.  If Garmin's numbers for calories burned were correct, I should be gaining weight based on the calories I am consuming, but I am not.  I have been holding at 175 for over a year, so I think my other sources for calorie consumption data are much more accurate than Garmin's.

  • Typically it is rather accurate, assuming the entry data (especially the HR and HRV), and the settings are all right (including the Activity Class). Depends also on the watch model and age - different models have different sensors, and use different algorithms.

  • Does your heartrate data look right for the activity?  If HR is off, the calories will be way off.

    One course I do regularly normally results in 800-900 calories reported.  2 weeks ago, exactly the same course/distance/time resulted in 316 calories, and a few weeks before that 347 and 404 calories. Those activities have crazy low HR for large sections, with averages 30-40 beats lower than normal.

    (Fenix 5 Plus, using the built-in HRM)

  • I have a VivoActive3 that I bought brand new in Nov and received end of Dec 2020.  I am thinking I will return it on Monday since both calorie and sleep data seem to be unreliable.

  • HR appears to accurate.

  • Thanks for everyone's input on this problem.  I rode the bike 53 miles today in the cold for 3 hours 20 minutes.  My heart rate maxed at 145 and I stayed in the green and yellow HR zone for most of the ride.  For this effort, Garmin awarded me 0 intensity minutes and 1000 active calories.  I am returning the VivoActive3 and will wait for the bugs to be worked out in future product iterations before jumping back in.