How are daily calories calculated?

[bigmomck]

My first day on the FitBit and it appears that I can have 890 calories.  I find that odd as anything below 1000 is pretty extreme.  I can't figure out how this is calculated.

[Heybales]

Fitbit estimates what you burned all day. Say 2000.

You picked a weight loss goal. Say extreme 2 lbs weekly so 1000 cal deficit daily.

2000 - 1000 = 1000

Suggest not picking such an extreme goal if you really don't get around that much to cause a higher TDEE.

So basically you caused it by your selection.

Because indeed, reasonable for a purposeful slow loss with wise choices is much to be preferred over slow loss because your body forces it on you from unwise choices.

The latter is going to have some muscle mass loss involved - and that sucks big time for continued weight loss and maintenance.