Over 90% of analyzed weight control apps track their users

Stepping into a new year, many set out to achieve their weight loss goals, often turning to weight control apps for guidance and support. These apps can be incredibly helpful in tracking calories, planning meals, and staying motivated. However, the number of options available can be overwhelming. Let’s explore which popular weight control apps effectively support your journey while also keeping a close eye on your personal data.

Key insights

• The analysis of 15 most popular¹ weight control apps focusing on nutrition reveals that they collect an average of 13 types of data — nearly one-third of the 35 data categories defined by Apple.
• The Noom app is identified as the most data-hungry among the most popular iPhone apps in the weight control category. Since its launch, the app has seen the majority of its downloads come from the United States and the United Kingdom, which together make up 66% of its total downloads. Meanwhile, Germany, South Korea, and Canada each contribute 5% to the overall download number.¹ According to the privacy policy on the App Store, Noom collects 22 out of 35 unique data types — nearly double the average of 13 data types. Furthermore, analysis reveals that over 53% of the 15 apps analyzed collect more unique data types than the average.
• In terms of tracking, the analyzed apps may use approximately three different data types. “Tracking” in this context refers to the practice of linking data collected from the app with third-party data for targeted advertising or sharing data with data brokers.² Our analysis indicates that nearly 47% of the apps examined surpass the average, collecting a higher number of unique data types for tracking. Noom again stands out, leading the group with seven different data types. Notably, Calorie Counter + is the only app in the analysis that claims it does not collect data, which may be used to track you.
• One-third of the apps analyzed not only collect a greater number of data types than the average but also engage in above-average user tracking. The five apps that fall into this category include Lose It!, Fastic, Noom, WeightWatchers, and Simple. ​​While these apps may offer great convenience, they also raise potential concerns about user privacy.
• In exploring the data types that most popular apps in the weight control category might use to track users, these can range from your email address and photos or videos to even more sensitive information. Notably, there are two apps that track a category labeled as “Other data types.” This category encompasses any data types not specified in the App Store's list for app privacy practices.² This ambiguity raises questions about how aware users are of the data being collected.
• MyNetDiary and HitMeal are among the apps that might track users with data classified as “Other data types”. Over their lifespans, the HitMeal app has attracted the majority of its downloads from the United States and the United Kingdom, accounting for 57% and 13% of its total downloads, respectively. Likewise, MyNetDiary has also seen a substantial share of its downloads from these two countries, with 54% coming from the United States and 13% from the United Kingdom.¹

Methodology and sources

For this analysis, the 15 most downloaded apps were selected from an AppMagic list, using criteria such as category (Weight Control), geography (West), store (App Store), and year (2024). Only apps with a primary focus on nutrition were included. Information on apps’ data collection practices was sourced from the App Store on January 8, 2025. The App Store provides a list of 35 unique data types categorized into 16 categories.² In this study, the data was analyzed based on the number, type, and handling of the data types collected by each app.

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