QoFast - Intermittent fasting tracker

Intermittent fasting apps are a crowded category dominated by a handful of incumbents that have spent years compounding on weight-loss positioning. Most look and feel identical: a timer, a few preset windows, a weight chart, and a paywall. Two structural gaps stood out to us:

Extended fasting is poorly served. Multi-day fasts (3, 5, 7 days) demand structured preparation and refeeding phases, and almost no consumer app treats those phases as first-class. Users end up taping together blog posts and Reddit threads.

The experience stops at the timer. People fast because of what is happening inside their body, but most apps abstract that away into a single progress ring. The physiology glycogen depletion, ketosis, growth hormone, autophagy — is the actual product.

Internally, Qorinx had a second problem: we needed a public, polished proof point for the studio model. We commit to consumer MVPs in 1–2 week cycles on shared Flutter/Firebase/RevenueCat infrastructure. QoFast had to ship at that cadence and still look and feel like a category-credible product on day one not a prototype with our logo on it.

1. Reframe the category, don't compete on it

Rather than position QoFast as another weight-loss tool, we anchored it in circadian and metabolic health. The hero promise became “the fasting app that shows what’s happening inside your body,” with phase tracking fat burning, ketosis, autophagy as the central narrative. Weight loss is a side effect of the science, not the headline.

2. Make extended fasting the wedge

We treated extended fasting as the differentiator rather than a feature buried in a settings menu. A full prep → fast → refeed cycle for 3, 5, and 7-day fasts became the core Pro use case. That gave us a defensible position the incumbents couldn’t cheaply copy without rebuilding their information architecture.

3. Build on the shared Qorinx stack

QoFast runs on the same Flutter + Firebase + RevenueCat foundation we use across the Qo-prefixed portfolio. RevenueCat handles entitlements and paywall attribute routing; Firebase covers auth, sync, and analytics. Reusing this layer is what makes a two-week build economically sensible the studio amortises infrastructure across every app.

4. Engineer the timer as a trust feature

A fasting timer that drifts, resets, or dies on a device restart is a category-killer. We built the timer to calculate progress from a saved start timestamp rather than a running counter, so it survives app kills, OS suspensions, restarts, and airplane mode, and works fully offline. Data syncs when the device returns online.

5. Ship the surface, not just the app

Launch surface was scoped alongside the app: a marketing site at qofast.com, an ongoing science-backed blog, App Store and Google Play listings with full metadata, and a web subscription path independent of the store paywalls. The case for the studio isn’t “we can build an app” it’s “we can put one in market.”

The app
- Live on iOS and Android, free to download, with a Pro tier at $7.99/month or $5/month billed annually.
- 13 physiological milestones tracked in real time, from blood sugar normalisation at hour 0 through immune regeneration at 48h and maximum benefit at 72h.
- Preset fasting windows (16:8, 18:6, 20:4, OMAD) plus structured 3, 5, and 7-day extended fasts with guided preparation and refeeding phases.
- Offline-resilient fasting timer with phase indicator (fat burning, ketosis, autophagy).
- Water intake logging with quick-add buttons and 6-state mood tracking throughout each fast.
- Fasting history with streaks, average duration, completion rate, and the ability to backdate and edit past fasts on Pro.

The commercial surface
- Marketing site at qofast.com with multilingual support and clear free-vs-Pro positioning.
- Web subscription flow at qofast.com/subscribe, bypassing store fees where appropriate.
- Content engine: a science-backed blog producing recurring posts on hydration, electrolytes, and extended fasting protocols.
- App Store and Google Play listings with full ASO metadata, screenshots, and category positioning.

The platform contribution
QoFast also paid back into the studio. Patterns proven on this build — RevenueCat paywall attribute routing in Flutter, the timestamp-based offline timer, the marketing-site-and-blog scaffold — are now reused across the Qo portfolio, shortening the next MVP by days rather than reinventing each layer.

Outcome
QoFast shipped to both app stores on the studio cadence we promise externally, with a public marketing surface and an active content engine on day one. It validates the Qorinx thesis: with shared infrastructure and a sharp category bet, a solo-led studio can put a credible consumer health app into market in weeks, not quarters and the proof is downloadable.