The Data Popular Health & Fitness Apps Have On You

Which data could possibly be more personal than your health and fitness stats?

In the age of the app, we’ve grown used to trading our privacy for free gadgets and magical phone software. You might feel queasy at the prospect of data-sharing when a fitness app demands everything from your shoe size to your appetite to your nocturnal behavior. But the flourishing of Fitbit, Eve, and Calm proves that if an app can make you healthier, fitter, or – let’s face it – sexier, many of us are willing to share our vital statistics.

Supplement Timing analyzed the official privacy policies of the top health and fitness apps to see which data each one asks of its users. We identified 27 different data types and gave the apps 2 points for each type they track by default and 1 point for types that require user permission. The ones with the most points are the ones that are most data-tracking-intensive.


  • The app that tracks the most data is a medical app called PlateJoy, which collects 18 types of data and has a score of 29 points.
  • Fitbit is the third hungriest data-tracker in our study, with 27 points.
  • Nutrition & Weight Loss apps track 15 of the 27 data types, and this is the top category because they are most likely to track that data by default.
  • The least data-intrusive app is a mental health tool, WorryWatch, which only uses the device data it gets from the app store.

Nutrition App Demands Most Personal Data

PlateJoy is the most personal data-hungry app in our study. The nutrition app collects 18 of the 27 possible data types – eleven of them by default. Ongoing data collection helps the subscription-based service to personalize a weekly menu and grocery shopping lists for users.

Nutrition and Weight Loss apps occupy four of the top ten places in our study. Apps like MyFitnessPal offer the chance to socialize your workout regime – becoming accountable to and encouraged by friends and strangers on the network. This makes for an effective approach to fitness, but such apps may connect the dots between your data and your social media presence and pass the findings to third-party advertisers.

Amwell and Heal Are The Most Invasive Medical Apps

Amwell and Heal are telemedicine apps that give you the ability to have a virtual visit with your doctor, and they are also two of the data hungriest medical apps in our study. With news breaking that Amazon’s in-company telehealth service is to be made available to other employers, the sector is likely to be one of the busiest and most controversial of the 2020s.

PlateJoy Is The Most Invasive Nutrition & Weight Loss App

Nutrition & Weight Loss apps are the most data-hungry across the categories. On average, they track 9 parameters by default. PlateJoy is the hungriest, with a score of 29. The ‘personal meal planning assistant’ collects 10 data types by default. PlateJoy gorges on data, crunching details, such as which type of milk each of your family members enjoys, to provide plans that account to the household’s tastes and health goals.

Eve Is The Most Invasive Women’s Health & Fertility App

It all starts to get a bit Handmaid’s Tale when you start collecting data about fertility. In fact, a UK-based charity called Privacy International found that this sector wants to know everything from the pills you take to your masturbation habits. They found that apps including second-placed Flo, save this data centrally to their servers, although Flo insisted that this data wasn’t used to automate decision-making.

FitBit Is The Most Invasive Step Counter App

The simple step-counter. How much can it need to know? In the case of top-placed Fitbit, it’s eight types by default, 11 by option, giving a score of 27 – just two short of the overall number one, PlateJoy. Indeed, half of our top-ten step counters have a score of 20+. Concerns have arisen about such apps being misused as productivity monitors by employers.

Couch to 5K and Strava Are The Most Invasive Running Apps

The title of the most data-hungry app in the running category is tied between Couch to 5K and Strava. Lockdown was reported to boost Couch to 5K downloads as hundreds of thousands downloaded the NHS-backed running app during the coronavirus pandemic.

Peloton Is The Most Invasive Cycling App

Peloton is the most data-hungry app in the cycling category. It is one of the few health and fitness apps that can store your voice recording (at the user’s discretion). The idea of this function is that you can chat remotely with friends while you work.

Sworkit and Workout Trainer Are The Most Invasive Workout Apps

Sworkit and Workout Trainer are neck-and-neck for most data-hungry workout app. Each has 26 points, but Sworkit comes out on top with more default data categories. However, Workout Trainer is the only one to default to collecting details on your family and friends – apparently to facilitate the app’s network-oriented design.

Down Dog Is The Most Invasive Yoga App

Four of the 10 least data-hungry apps in our study are for yoga. Yoga Workout is the fifth least data-intensive app of all, requiring only your email address, device details, and the workouts that you choose. Even yoga’s biggest data farmer, Down Dog, has a score of just 21 points.

Calm Is The Most Invasive Sleeping App

Sleep is another low-data activity. Slumber offers meditations, stories (read by a hypnotist), soundscapes, and music to help you nod off. It asks only for your email and device info in return (4 points). Calm offers a similar service but wants your socials, sleep schedule, age, sex, and address, bumping it up to 19 points.

Calm Is The Most Invasive Mental Health App

Calm also comes out as the most data-hungry mental health app. But in general, this category is not data-intensive. Most apps only want contact and basic personal details, plus one or two others such as language or social media. WorryWatch is the least data-hungry app in our whole study, requiring only the device info necessary to make it run. The app works like an analytical anxiety diary, so privacy is of the utmost importance.

Find Your App

Wondering how your favorite health app works out for data intrusion? Search for it in the table below, or sort the details by name, category, or tracking score.

Fitter, Stronger, Better Informed

If app data is misused or misplaced, it could compromise your employability and health insurance. And some firms may have more political ideas about how to exploit your data: one investigation found that Femm, a fertility app, was funded by anti-abortion, anti-gay Catholic campaigners and “sows doubt about the safety and efficacy of hormonal birth control.”

Health and fitness apps can be a superb way to get information and get motivated when it comes to your personal well-being. But it is essential to approach each one critically and make an informed choice before adding it to your phone and sharing your personal data. Make sure you know what information the app wants, what it might do with it – and who are the people behind the pleasantly-colored interface.


The original version of this article included fertility and women’s health app Maven among the health & fitness apps in the ranking. We decided to remove it from the ranking after representatives from Maven expressed concerns about the way in which the data was categorized. They also explained that “a healthcare app should not be compared to a fitness app. We connect Maven users to clinicians (doctors), and the data you’d choose to share with a doctor, for example, is very different than what you’d choose to share with a workout app or meditation app.”


Health and fitness apps were gathered from a variety of sources such as VeryWellFit, Healthline, CyclingNews, and Men’s Health.  For each app, we analyzed the official privacy policy as provided on their website or on the website of the parent organization. In each privacy policy, we examined what types of personal data the app collects about its users. 

Where possible, a distinction was made between the information users have to provide to use the app and its features, and the information users can choose to share with the app.  For each of the 27 types of personal data identified, we gave an app 2 points if a certain type of data was tracked by default and 1 point if that type of data was tracked only if users gave permission for it to be tracked. 

Apps with the highest overall score were deemed the most tracking-intensive. Research was carried out in Feb 2021.


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