Ask HN: Are there any good, privacy-respecting health/activity trackers?

Now that we're in January and many of us will be thinking of our health, I wondered if Hacker News readers have some recommendations for health/fitness tracking hardware like heart rate monitors, step counters, etc., ideally in watch form that respect privacy.

I've looked devices from Fitbit, Polar, TERMINICE, etc. but I don't like the idea of hardware that requires a closed source app to access or visualise your data. The risk that they sell, use your data against you or lose your data in a breach is too high. Ideally I'd like something that logs health parameters then lets you transfer it over a LAN/Bluetooth to a computer for further analysis. Other functionality like GPS tracking, music etc. is a plus.