What Your Health App Does With Your Data

Health and fitness apps can be wonderful companions, and they ask for quite a lot in return: your weight, your meals, your mood, sometimes your location. Most of us tap “agree” without reading, and that is perfectly human. The good news is that a few quick habits make it easy to enjoy your apps with confidence. Here is what researchers found when they peeked under the hood, and a short checklist to help you choose well. This is general education, not legal or medical advice.

A look at 24 popular apps

In 2019, Grundy, Held and Bero published a study in the BMJ that analyzed the network traffic of top-rated medicines-related apps. They chose 24 apps from 821 found in app stores, ran each on a phone with scripted use and watched where the data went.

• Sharing was common. 19 of the 24 apps (79 percent) shared user data with other parties.
• Many parties were involved. The data reached 55 unique entities owned by 46 parent companies, including developers and outside service providers.
• It was hard to see. Coverage of the study stressed that the sharing was often not clearly disclosed, and that a few companies could combine data from several apps and potentially re-identify users.

The sample was small and focused on one kind of app on one platform, so the percentages describe those apps, not the whole market, and practices keep improving as laws and app stores change. Still, it is a helpful nudge to take a minute and check, and that minute is well spent.

Your quick and easy checklist

• Read the privacy label. App stores now show a short summary of what an app collects and whether it is linked to you. It is a great first look.
• Ask what is really needed. Does the app need your name, contacts or location to count steps or log a meal? If not, skip it or switch it off.
• Look for clear statements. Good policies say whether data is sold or shared, with whom and why, and how to delete your account.
• Use your phone’s permissions menu. You can switch off camera, location, contacts and notifications for any app in settings.
• Share thoughtfully. Free-text notes can hold sensitive details, so add only what helps you.
• Tidy up now and then. Delete apps you no longer use and close accounts you do not need.

How Weight Wire approaches it

Disclosure: Weight Wire offers its own free tools, so we try to hold ourselves to this same standard. Our privacy promise says we do not sell or share individual user data. Ads do not appear in your private journal, library, account pages or Food Lookup, and your journal entries, saved results and saved foods are visible only to you. You can download your journal or delete your account any time. Our privacy policy has the full details.

More to explore

Apps can be great for building habits, as we describe in the positive outcomes of using a weight-loss app and why it is good to keep a food journal. Our guides to AI chatbots for nutrition and wearable heart rate variability cover other tools worth enjoying thoughtfully.

Sources

• Grundy Q, Held FP, Bero LA, et al. Data sharing practices of medicines related apps and the mobile ecosystem: traffic, content, and network analysis. BMJ, 2019;364:l920 (figures from the abstract and university summaries).