Just reading the CBC article (http://www.cbc.ca/news/technology/fitness-trackers-monitoring-users-1.3428817) about Garmin transmitting our data unencrypted ("The Citizen Lab researchers conclude the Garmin app, called Connect, sends heart rate, workout and movement data across the internet without encryption.").
I chose Garmin as I thought that, given they'd been in this business for a long while, they'd have security buttoned up.
Really worrying.
The article also talks about people being able to hack your data. Maybe this explains why I've had some days where I've apparently walked over 30,000 steps while spending the whole day at home without exercising.
It appears Garmin declined to comment. That's almost more worrying than the lack of focus on data security as it implies they've nothing to counter it with.