"Recently, a slew of reports have popped up showing how fitness apps are logging and selling off your data to ad companies, city planners, and others. By their nature, these apps have a lot of sensitive personal data about you that you might not want out in the world. Let's take a look at what's going on."

http://lifehacker.com/lots-of-health-apps-are-selling-your-data-heres-why-1574001899