(WXYZ) - Chances are you've downloaded a health or fitness app on your smartphone.
The industry is skyrocketing and expect to grow by 26 billion by 2017!
Millions of people use them and enter information about everything from their diet, to health conditions, to even sexual activity.
While these apps can have some amazing benefits, we've found your privacy could be in critical condition.
Avid biker Matt DeMargel pedaled his way to losing 30 pounds...and credits health and fitness apps for helping him with the transformation.
"The apps have been very critical in helping me achieve my goals," DeMargel said.
Matt enters his height, weight, everything he eats, and how much he exercises into one app.
He then uses another to track each bike ride.
But Matt realizes he's not the only one watching his progress.
Research by Evidon, a privacy technology company, found many popular health, wellness and fitness apps share your data with third parties.
"I've made a choice that being that this was going to help me from a health perspective, that I would take the privacy risk," DeMargel said.
How big a risk could you be taking?
If apps are used to transmit information to your doctor, pharmacy--or any health care plan or provider, that data is confidential...protected under strict federal health information privacy laws.
This study, by privacy rights Clearninghouse, reveals more than a third of apps it reviewed sent data to parties it didn't disclose.
Cora Tung Han of the Federal Trade Commission said, "I think that's troubling. In the health and fitness context, where consumers are used to thinking about sharing their information in the traditional provider context, I think they might be surprised about the collection of information that's happening."
The same study found a majority of apps sent data over unencrypted connections.
The Federal Trade Commission is on the case.
The FTC warns app providers need to let users know exactly who's watching their every ride, tracking their pregnancy or their blood pressure.
"We do look at whether or not apps are honoring what they say in their privacy policies, and also whether or not they are living up to what they say to consumers in the app itself about what they're doing with their information," Han said.
The application developer's alliance says it encourages app makers to be upfront about data collection.
And the organization was quite up front with us: admitting targeted ads are a significant reason for sharing info and a significant source of revenue in the industry.
Jon Potter of the Application Developers Alliance said, "so if you have high blood pressure and you are telling the app, 'I have high blood pressure,' you should expect you're going to get advertisements for high blood pressure medicine."
Matt says despite the risk of data sharing and unclear privacy policies, he's not putting the breaks on his beloved apps anytime soon.
He just follows his own rules of the good road, which experts agree is a good way of gauging if an app is right for you.
"I just make sure if it's out there it's something I'm comfortable with the whole world knowing," DeMargel said.
Some other privacy tips: If you can find an apps policy, be sure to read it carefully and make sure you feel comfortable with it.
The FTC is recommending app developers offer a "do not track" program similar to the one that exists for web browsing.