Two years ago users of the digital fitness tracker Fitbit were surprised to find their sexual activity, as recorded by the device, appearing in Google search results. “Way to go, Jeff,” tweeted columnist Andy Baio, linking to one high-performing example. The records were promptly removed, but Fitbit faced few repercussions for the leak.

How secure is the data we volunteer to tech companies? There’s a new movement called life tracking, and its proponents—who record everything from their moods to the quality of their sexual encounters—are about to find out. Using a variety of digital devices, companies like Fitbit store and analyze data about life trackers’ bodies while promising to protect the information. The companies claim they can help people lose weight, increase productivity and even predict illness. and similar websites use the data to gain insight into conditions including kidney disease and asthma. But insurance companies and employers can use this information against you.

Lawmakers are years behind technologies that collect data on the scale of life tracking, says Rainey Reitman, activism director for the Electronic Frontier Foundation. “The Health Insurance Portability and Accountability Act protects health information but only with health care providers and insurers,” says Reitman. “Consumer devices aren’t covered.” She adds that state laws and privacy policies vary widely. A Carnegie Mellon University study found it would take a person 244 hours, or roughly 40 minutes per day, to read every privacy policy encountered in a year. And when companies go bankrupt or merge, data can be wielded in ways users never intended.

Data this sensitive have a tendency to leak, no matter how they are regulated: In 2012 more than 1.7 million U.S. medical records were reported as leaked across 223 breaches. And those were just typical medical files, less detailed than the data logged by life trackers. What happens when the movement goes mainstream?

“Companies that produce life-tracking devices are going to need a self-policing association to avoid regulatory crackdowns later,” says author Tim Ferriss, who meticulously tracked his fitness for his book The 4-Hour Body. He adds that danger lies in losing sight of your goals. “Data are just numbers,” he says, “but information is what you can apply to your own life. And there’s a big difference between tools that provide data and ones that provide information.”

Such technologies can change lives, but the companies that make them can’t be trusted with our most personal information. Regulators won’t protect you, and nobody has time to read the policies that apply to the data they generate. Fancy pedometers may look cool, but buyer beware.