I think the Fitbit should be classified as a class 1 device. some of this devices still had sensors to collect health-related information such as; heart rate and blood pressure. Which full under general control. But, I think they classified it as Class 2 due to Software involve in this type of calculation. The first department for such a project should be CDRH as it can be a medical device. Marketing for such devices heavily relay on improving health and motivate people to exercise more under the supervision of this devices calculation.