Possible double counting of BMR in calories burned (Charge 6)

[IgorA.]

I’ve noticed a consistent overestimation of calories burned on my Charge 6. Example: a 70 minute walk (5 km, HR 100–110 bpm) shows 619 kcal, while realistic calculations based on METs and weight (88 kg) suggest 300 kcal.

Hypothesis: Fitbit may be including basal calories (BMR) inside the activity calories, and then adding full BMR again to the daily total. This would explain why daily burn is inflated (3300 kcal vs expected 2700–2900).

Could you clarify how Fitbit separates resting calories vs active calories? It looks like BMR is being counted twice.

[LZeeW]

Hi @IgorA.   Fitbit doesn't separate BMR from activity calories.  It is a running total.  Your exercise detail calorie burn is the total for that time period.  MET calorie burn from a database is activity only.  Fitbit doesn't add your BMR again.

Every brand of fitness tracker with a heart rate monitor uses its own algorithm to estimate activity calories.  Fitness trackers and smartwatches don't have a stellar reputation for calorie burn accuracy.

[IgorA.]

I do understand that Fitbit doesn’t separate BMR from activity calories, and that it’s shown as a running total.

However, this is exactly the problem from a user perspective: the numbers become unrealistic. Burning 600+ calories during one hour of light walking is simply not physiologically possible for someone of my weight and pace, and a daily total of 3500 kcal is also far beyond a realistic range.

[LZeeW]

@IgorA.   Like I wrote, fitness trackers don't have a stellar reputation for calorie burn accuracy.