Zero: Fasting & Health Tracker

What it does

Zero is a comprehensive health and wellness app centered around intermittent fasting. It provides users with a timer to track their fasting and eating windows, tools to log various health metrics like weight, sleep, and activity, and a rich library of educational content. The app aims to guide users toward their health goals, primarily weight loss, by personalizing their experience based on data and providing expert-led content.

Where it shines

Zero excels at making data feel personal and actionable. The onboarding process, while lengthy, culminates in a powerful moment where it visualizes your projected weight loss on a graph (01:37), turning abstract goals into a tangible timeline. Once in the app, the customizable trends dashboard (11:13) is a standout feature. It allows users to plot different metrics against each other, like fasting hours versus glucose levels (11:29), empowering them to uncover personal health insights. Finally, the app effectively uses celebratory moments, like earning a badge with a burst of confetti after completing the first fast (03:30), to reinforce positive habits.

UX highlights

Contextual Onboarding: Instead of a long upfront tutorial, Zero uses a series of coachmarks on the main timer screen (03:02) to teach core functionality in context, which is more effective for retention.
Layered Goal Setting: The app first asks for a primary goal (weight loss) during setup (01:25), then later prompts for deeper motivations like 'gut health' (09:35), allowing for progressive personalization without overwhelming the user initially.
Clear Data Entry: Logging data like meals (04:25) or weight is straightforward, using clean modals that focus on one task at a time.
Rich Content Library: The 'Learn' tab (05:23) is well-organized with filters for articles, videos, and audio, making it easy for users to find expert content relevant to their goals.
Achievement System: The app uses badges and milestones (08:55) to gamify the process of building healthy habits, providing consistent positive reinforcement.
Customizable Interface: Users can re-order graphs on their dashboard (08:15) and customize charts in the trends section (11:19), giving them control over how they view their data.

Monetization & growth

Zero employs a hard paywall model, requiring users to subscribe before accessing the main app features. During onboarding, it presents a paywall (02:05) that highlights a 7-day free trial for an annual plan, alongside a monthly option. The screen uses social proof by displaying logos of major publications like Women's Health and TechCrunch. After a successful subscription, a welcome screen immediately reinforces the value of 'Zero Plus' (02:24), helping to mitigate potential buyer's remorse.

Who it’s for

This app is clearly designed for individuals serious about making a lifestyle change through intermittent fasting. Its data-rich environment and customizable charts appeal to users who are analytical and want to understand the connections between their habits and outcomes. The extensive library of expert content also makes it suitable for those who are new to fasting and looking for credible guidance. The focus on challenges and streaks suggests it's for users motivated by gamification and community engagement.

Notes & opportunities

The onboarding flow is quite long and requires a significant amount of personal information before showing the paywall. While this builds investment, it could also be a point of drop-off for less motivated users. The app asks to verify the user's email multiple times via a banner (08:11), which could be integrated more smoothly into the sign-up process. Finally, the process of deleting a previously logged fast is slightly convoluted, involving multiple taps through a history screen (10:57 - 11:02).