How Fitness Apps Leak Your Most Personal Data

You open your favorite fitness app, start tracking your run, and feel good knowing you’re taking care of your health. But what if that same app is quietly collecting — and selling — data about your location, heart rate, sleep, and daily routine?

Fitness and health-tracking apps know more about you than almost any other service. They record when you wake up, where you go, how fast your heart beats, and sometimes even your emotional state. Many of them don’t keep this data to themselves — they share it with advertisers, data brokers, and analytics companies.

Your most private information — the kind you’d never post online — can end up fueling ad algorithms or sitting in databases you’ve never heard of. Here’s how it happens, and how to protect yourself.

What Fitness Apps Collect (and Why It’s a Problem)

Most fitness apps ask for far more data than they actually need to track your workouts. It starts with the basics — your name, age, gender, height, and weight — but quickly goes deeper. Many collect location data to map your routes, heart rate and sleep patterns through connected wearables, and movement patterns through your phone’s sensors. Some even estimate stress levels, or sync with your diet apps to analyze what you eat.

This might seem harmless at first — after all, the data helps you track progress and reach goals. But here’s the catch: that same data is incredibly valuable to advertisers, insurers, and data brokers. Your location can reveal your home and workplace; your activity patterns can suggest your habits, or even health conditions.

Once collected, this information is often shared or sold, sometimes in “anonymized” form — a term that doesn’t mean what you think. Studies have shown that anonymized health data can be re-identified with shocking ease when combined with other datasets.

Out of the most popular apps, Strava, Fitbit and Nike Training Club are the most data hungry. Centr on the other hand, is the most respectful of it's users privacy.

How Fitness Apps Leak Your Data

Fitness apps don’t always “sell” your data directly — sometimes they simply share it so widely that it’s almost the same thing. One of the biggest culprits is third-party integrations. When your fitness app connects with social media platforms, advertising networks, or “analytics partners,” it often sends them your data — sometimes including exact GPS routes, workout habits, and biometric readings. These companies use that information to build detailed advertising profiles or train their algorithms.

And then there’s the growing problem of data breaches. Health and fitness data is a goldmine on the black market. Hackers can use it to commit identity theft, or target people based on their health conditions. Even if your data isn’t stolen outright, it can still leak through ad trackers embedded in the app, quietly sending information to dozens of companies every time you open it.

Why It Matters

Health data is among the most sensitive information you can share — and once it’s out, you can’t take it back. A leaked email address can be changed; a leaked medical status record cannot. That kind of data paints a deeply personal picture of who you are — your daily routine, medical conditions, or your habits.

This isn’t just theoretical. Fitness app data has been used in ways most users never imagined. In 2018, location data from Strava’s fitness tracking map exposed the locations of secret military bases when soldiers logged their runs. On a smaller scale, employers and insurance companies have shown interest in buying aggregated fitness data to monitor “healthy behavior.” It’s a slippery slope between motivation and surveillance.

When your health and location information become another line item in a marketing database, the impact goes far beyond ads — it touches your safety, privacy, and autonomy.

How to Protect Yourself

You don’t have to give up your fitness apps to stay safe — you just need to take back control over what they can see and share. Start by reviewing app permissions on your phone. Many apps don’t actually need access to your location or contacts to function. Disable anything that isn’t essential. On Android and iOS, you can limit location access to “while using the app” or turn it off entirely.

Next, look carefully at the app’s privacy settings and turn off data sharing or integrations with third parties. Avoid signing in with Google, Facebook, or Apple accounts — these logins make it easier to link your fitness data with your broader online profile. Instead, create a separate email just for health apps.

Consider using privacy-focused fitness alternatives, like open-source apps that store data locally rather than in the cloud — for example, Gadgetbridge, FITOTrack, or RunnerUp. Pairing these with a VPN can also help mask your location from trackers when the app connects online.

Also, if you have the funds, you can use paid apps or buy subscriptions. Most of paid versions are far more private than their free counterparts.

Finally, remember that less is more. The fewer apps that have your health data, the less exposure you face. Delete old or unused accounts, and regularly check which devices have access to your fitness information. Treat your health data like you would your credit card details — private, sensitive, and valuable.

Final Thoughts

Fitness apps promise to help you live healthier, but too often they come at the cost of your privacy. The same data that tracks your steps and sleep can reveal intimate details about your habits, health, and location — and once shared, you can’t take it back. By controlling app permissions, using privacy-friendly alternatives, and being selective about what you share, you can still enjoy the benefits of fitness tracking without giving away your personal life. Your health data belongs to you — not to advertisers, data brokers, or anyone else.