http://help.fitbit.com/articles/en_US/Help_article/How-does-Fitbit-know-how-many-calories-I-ve-burned http://help.fitbit.com/articles/en_US/Help_article/How-doe

http://help.fitbit.com/articles/en_US/Help_article/How-does-Fitbit-know-how-many-calories-I-ve-burned http://help.fitbit.com/articles/en_US/Help_article/How-does-... "Calorie estimation is used when no activities are logged or data is synced." If that's accurate, then it only "broke" calorie burn estimation on days when you didn't wear your Fitbit.