Calorie history is wrong

[Smith16]

I bought my first Fitbit on June 18, 2019. When I finished setting up the Fitbit Versa it was showing the calorie history going all the way back to 2017. How can it go back to 2017 when I just bought this device as my first ever Fitbit? Plus the device is brand new.

[wtksk8r]

One question - are the prior daily calorie numbers the same going back to 2017? If it is then Fitibt might be filling in the earlier data with your BMR (Base Metabolic Rate) to provide a starting average for calories expended per day.

[Smith16]

The numbers changes throughout the calories burned history. In a weird way too. 

From January to April 2018 it says something like 1,480 calories. 

April to June 2018 it says something like 1,490 calories.

January to May 2017 it says something like 1,413 calories.

May to December 2017 it says something like 1,423 calories. 

Is it wrong for me to think it should not have any data showing for any dates prior to June 18, 2019? Since June 18, 2019 is when I actually got my first ever Fitbit. 

[wtksk8r]

I went back to my history (I've not checked it before) and found the same thing. It does assign me a constant 1550 calories per day which is around my BMR. I suspect the algorithm pre-populates the prior years with your BMR. Could be either a shortcut in the algorithm or possibly something the program uses to estimate an average daily calorie burn until it gets enough data from actual usage.