Fitbit is looking for impacts - if it's on your wrist it is seeing what it thinks are step impacts to some degree.
If you look at your 24 hr daily graph of steps, distance, calorie burn, you'll likely find that while some bogus steps are seen - the resulting distance and calorie burn is super minor.
There are settings and advice regarding dominate hand and which selection to try to minimize those bogus steps.
From distance and known weight and time comes very accurate formula for calorie burn.
Sadly not accurate if no actual distance was done - but again, probably minor.
But yes, the majority of your daily burn is BMR - and depending on your stats - you could easily have 1334 calories burned by 1 pm.
It could also be doing some movement before 1 pm, or are you in bed until then?
To lose weight you merely need to eat less than you burn in total, hopefully just fat weight if done right.
Fitbit is coming up with that daily burn total, subtracting some for weight loss if you indeed set that goal - and giving an eating goal figure to reach.
You are not a size 0 because you likely have no concept how many calories are in food that you used to eat, just as you are not aware how many you really may burn daily.
You just don't happen to know, many don't. Fitbit and other trackers are an eye opener to the whole world of calories burned and eaten.
Some of your language is confusing since you don't understand the concepts so I'm not sure what you are talking about with having the jog counter instead of the BMR one.
As to your diet and being accurate on that side of incoming food - logging by weight is best, because calories is per gram, not cups, spoons, ect. (except liquids).
Another eye opener perhaps.
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