Your boss could soon know exactly what time you go to sleep every night, if you go to Spin class – even how many calories you consume! And it could cost you thousands of dollars a year or even get you fired!

That’s because self-tracking smartphone apps and devices are flooding the market. Those are things like Fit Bit, and the new Nike Fuel Band, or apps like Run Keeper or Lose It. They monitor how many steps you take, how many calories you burn and consume – there are even ones that monitor your sleep patterns, heart rate, and mood. And soon, those apps and devices may be passing that data on to your employer, or insurance company.

Manufacturers say the apps are designed to help people improve their health. But the problem is, your health data isn’t guaranteed for your eyes only because a lot of app makers are now selling the data recorded about you to employers and health insurers. And that could spell trouble for you and your bank account.

For instance, Fit Bit is being used by corporate wellness programs. And another tracker called Body Media is working with insurance companies to get its devices into more workplaces. That’s because employers are desperate to cut health insurance costs any way they can. And if your self-tracking stats show you’re a binge-eating couch potato, that’s a red flag you’re at a higher risk of developing dangerous conditions, like diabetes and obesity. And your company could pass on the extra costs of health insurance to you – or flat out fire you.

Privacy experts predict that soon, health insurers could require you to use a self-tracking app before they even register you for a plan. And your no-sleep, zero exercise, and junk food ways could mean you have to shell out serious bucks for coverage.