I wore my Fitbit for the first time yesterday, and it credited me with around 700 calories burned. My exercise for the day was 30 fast minutes on the treadmill, plus some shuffling around the house cleaning and cooking. All in all, that's about half the exercise I normally get, and today my fitbit says I've put in 10686 steps and have burned 1494 calories, as of 2:20 pm. I've been functioning pretty much average today in terms of activity. I know when I sync my Fitbit with Spark tonight, it's going to show a very high number of calories burned through exercise.
So obviously Fitbit is not starting with the same formula Spark People does, which assumes a somewhat sedentary lifestyle and then allows you to add in your exercise calories as you go. But it's also not strictly counting calories burned, because my BMR is around 1500; I seriously doubt I only burned 700 calories all day yesterday.
Does anyone know how I should modify my exercise numbers so that Spark Reports (like Daily Calorie Differential) are still useful to me?