Where does Calories burnt come from?

[b1ritt5]

I just got a Fitbit a week ago and notice the calories burnt is a big number. I wake up first thing in the morning and it says 500. Seems weird. Also when I go into the Fitbit app and look for data from two weeks ago, it shows calories burnt! From before I had the Fitbit! So that means the data isn’t coming from the tracker and maybe health app (iPhone). Unsure and wondering if anyone has any thoughts.

[LZeeW]

@b1ritt5   Those calories you see when you wake up are your BMR calories.  Fitbit uses a known equation that uses your age, sex, and weight to estimate those calories.

It is a weird quirk (or possibly lazy programming) that you can see these calories in your app before you opened your account.

[YachatsMike]

FWIW:

Harris - Benedict BMR Formula

BMR for men = 66 + (13.7 x weight in kilogram) + (5 x height in centimeters) - (6.8 x age in years)

[LZeeW]

@YachatsMike   Fitbit uses the Mifflin St Jeor equation.