Fitbit One Driving/Steps/Daily Calories

My One rarely counts significant steps for me in a car, so if I log driving it would raise my calorie burn. I think that is a good sign it isn't adding too much if that is happening. I don't generally log non-exercise activity to my fitbit account, but I don't think their activity database is especially inflated. It has lower calorie burns than MFP for a lot of activities. It is based on accepted MET values for the activity, I think multiplying a minute of your RMR by the MET for the activity. This method does include BMR + the activity. I am not sure why you are seeing negative adjustments though, you are not logging it on MFP, are you? I would not suggest logging driving on MFP, I think you would only want to log it to fitbit to correct your steps and calorie burn (if you are getting false activity credit in the car). If your fitbit calorie burn decreases when you log driving, that is a sigh that you probably should log it. If it increases, you probably don't need to. If it stays about the same--whatever you prefer (log it if you want to correct the steps). I guess you might see a negative if your fitbit thought you were active, then you logged it and the activity was corrected. That is only because you were not as active as MFP expected at that time. MFP is only comparing what it expects you to have burned (from your BMR, activity level and MFP logged exercise) to your total fitbit burn. Since fitbit and MFP's BMR estimate are pretty similar, it should be that a higher Fitbit burn means you were more active but not the case if the higher burn came from "false activity" like riding in a car.