The intermittent-fasting app that doesn't track you.
Set the start time. Pick the milestones. Hit ACTIVATE. Your phone calls you at the right moments. That's the whole product.
Every other intermittent-fasting (IF) app I tried got it wrong in the same way: they treated fasting as a thing to track. So they shipped streaks, charts, weekly averages, completion rates, badges, calendars, in-app coaching, and a daily ritual of opening the app to log how you did.
Fasting doesn't need any of that. The protocol is simple — eat in a window, don't eat outside it. The only hard part is knowing when each biological milestone hits so you can decide, in the moment, whether to keep going. Everything else those apps add is friction, anxiety, or guilt-laundered as "engagement."
Interfast deletes all of it. The app is a single-purpose scheduler: pick a fast start time, check the milestone hours that interest you (12, 16, 18, 20, 22), tap ACTIVATE, put the phone in your pocket. The phone notifies you at each milestone with a STOP action; after the last one, the app disarms itself — the tape rewinds. Eat whenever you want. The app forgets, literally.
This is a deliberate stance against three failure modes that most habit / wellness apps share:
- Tracking creates anxiety. Logging a fast that "broke" punishes the user for what is in fact a normal, healthy break. Streak mechanics weaponize loss aversion against the very habit they claim to support.
- Onboarding kills the habit before it starts. Forcing the user to pick a protocol on day one (16:8? 18:6? OMAD? 5:2?) makes the decision feel weighty. The actual right answer is "fast until you're hungry, then eat" — and you can pick a longer milestone next time if it felt good.
- The phone in your pocket already knows the time. What you need from a fasting app is not a clock. You need an unobtrusive ping at the moments when your body crosses a threshold (glycogen depletion → fat oxidation → ketosis → autophagy → growth-hormone peak). That's literally five timestamps. A ringtone could do it.
So Interfast is closer to a kitchen timer than a wellness app. And we made the timer feel like a piece of TE hardware on purpose — because the act of setting it up should be tactile and satisfying, not a form to fill out.
- Drag the time wheel to where your last meal ended (or tap NOW). Tap the milestones you care about.
- Hit ACTIVATE. The deck locks; you cannot accidentally edit the schedule while running.
- Your phone fires a notification at each checked milestone. Tap STOP on any of them to cancel the rest — and after the final milestone the app disarms itself. That's it.
The single screen does everything. There is no settings page, no protocol picker, no statistics tab, no history calendar, no profile. Once you tap ACTIVATE, the app's job is to be silent until the next milestone — and when the last milestone fires, the app deactivates itself, so tomorrow never starts with cleanup. Habits stick when the cost of "doing it again tomorrow" is low — the cost of opening Interfast is one tap and one drag.
If you eat at hour 14 instead of waiting for 16, that is fine — it might even be the right call (you were hungry, you have plans, training session ran long). The app gives you a STOP button on every notification with no "are you sure" and no negative reinforcement. Tomorrow is identical to today.
This is the most counter-intuitive choice in the product. Every PM playbook says streaks drive retention. They do — they also drive the precise pattern (perfectionism → rebound → abandonment) that makes diet apps notorious. We optimize for fasting that outlasts the app, not for app-session minutes.
The five preset hours (12 / 16 / 18 / 20 / 22) aren't arbitrary picks; they map to biology:
| Hour | What's happening |
|---|---|
| 12 h | Glycogen reserves nearly depleted. Body shifts toward fat oxidation. |
| 16 h | Insulin baseline. Lipolysis active. Most popular IF protocol endpoint. |
| 18 h | Ketogenesis ramping. Mental clarity reported by long-term fasters. |
| 20 h | Autophagy markers measurable in research literature. |
| 22 h | Growth-hormone peak. OMAD-adjacent territory. |
You're not "competing" against these numbers. They're stations along a timeline; the notification just tells you the train passed one. Stop or keep going — your call.
The scrubber is built like an OP-1 tape transport: reels that rotate as you scrub (and roll continuously while the tape is LIVE), an LED row with one pip per milestone (red = armed, green = reached), a red position needle, and an instrument readout that shows only true data — ALARMS 02 · NEXT 08:09 · Δ −46m. This is not decoration — it converts the moment of picking a start time from a "fill out a form" feeling into an "operate a piece of equipment" feeling. People run a habit longer when the ritual is satisfying.
Every milestone notification posts as a music-player-style card: a dithered low-res poster bitmap as the backdrop (giant numerals, dot-matrix grid, the 24-segment strip lit to the hour reached), with the title overlaid at the top so the strip stays visible. Tapping STOP cancels every later milestone — no pleading, no "we hope to see you back." The final milestone carries no STOP at all, because there is nothing left to stop; it just says the tape rewound.
The notification is the entire UI surface for 99% of usage. It has to carry the brand and the tone alone. So we put real design effort into it.
Light/dark switches automatically based on your phone's brightness slider (read live via a ContentObserver on Settings.System.SCREEN_BRIGHTNESS). When you turn the screen down at night, the app goes dark. There's no toggle to flip — there's nothing for the user to manage.
No accounts. No cloud. No analytics. No identifiers. Schedule state lives in DataStore on the device. Notifications are scheduled via AlarmManager (local). Nothing leaves the phone. The Privacy section of this README is short because there's nothing to disclose.
Every control works under TalkBack: the milestone rows are real checkboxes with spoken descriptions ("12 hour milestone, alarm at 08:09 tomorrow"), the tape deck exposes ±5 min / ±1 h / set-to-now accessibility actions, ACTIVATE announces why it's disabled, and the TAPE LIVE/IDLE readout announces state changes. An instrument you can't operate isn't minimal — it's broken.
Tap the N° edition stamp in the header and the whole app flips over, Pocket-Operator style: a paper-cream printed back with the app's actual component diagram silkscreened in print colors (SCRUB.UI → SCHED.VM → DATASTORE, down through ALARM.MGR → NOTIF.RX → DITHER.ART), the TX-1 operator's manual as a legend, and the config switches — STREAKS, STATS, GUILT — printed permanently in the OFF position.
It's not a settings screen. It's the proof there isn't one. (RUNTIME ∅ — WE DON'T COUNT.) System back flips you home.
| Element | Purpose |
|---|---|
| Brand row | Red breathing mark + INTERFAST wordmark + N° {dayOfYear} ⟲ edition stamp. The square pulses while a session is running; tapping the stamp flips the unit over to the printed back. |
| Hero headline | start a fast. → armed. (start in the future) → holding. (running) → flowing. (a milestone fired) → done. (tape rewound). Each with a one-line mono sublabel that teaches the vocabulary. Five states, no settings menu. |
| Diagonal rule | A red 1dp line rotated 3°. Basel-poster grid break — a reminder this is built like a printed thing, not a Material template. |
| Tape-deck scrubber | TE-flavoured time picker. Drag horizontally to move the start time (one-time ‹ DRAG › hint on first run); long-press or the NOW chip snaps to now. System fling physics. Locks once active. |
| LED pips | One per milestone: red = armed, green = reached, dim = off. The pips tell the truth. |
| Reels | Rotate 12° per scrubbed minute, counter-rotating — and roll continuously while the tape is LIVE. |
| Wheel | 30-min major ticks with HH:mm labels around a fixed red needle. Whole-minute snap, so the displayed time is the exact alarm fire time. |
| Readout | ALARMS (armed count) · NEXT (next fire time, or ——:——) · Δ (offset from now in h/m; red when the start is in the future). Every field is real data. |
| Targets header | TARGETS // 02 — count plus, when needed, an amber hint (PICK AT LEAST ONE, ALL PAST — MOVE START). |
| Toggle rows | 01..05 index + check + hour + target time (+1D when tomorrow). Tap to toggle while inactive; full TalkBack checkbox semantics. |
| State badges | PAST rows dim to 45% with struck-through times. DONE goes phosphor-green when the milestone fired. |
| Ghosted numeral | Day-of-year mod 100, rotated 6°, alpha 0.06 — a poster mark that quietly changes daily. |
| Progress strip | 24 segments, lit count = max selected hour. How much of the day your schedule covers. |
| Primary action | ACTIVATE (red, full width) → schedules exact alarms and locks the deck. DEACTIVATE while running. |
| Footer mark | TX-1 // MANDRIGIN · 2026 plus a tri-dot status indicator. Tap it five times. |
Anti-feature list, because what we don't ship is part of the product:
- No accounts. You can't log in. There's nothing to log in to.
- No streaks. Missed days don't exist as a concept. There is no "day."
- No history. The app doesn't remember past sessions. After the last milestone it disarms itself; the slate is clean.
- No settings. The config switches exist — printed on the back of the unit, permanently OFF.
- No protocols. "16:8", "18:6", "OMAD" aren't presets — they're emergent from which milestones you check.
- No coaching, no tips, no nudges. No motivational copy. No "you got this!" No emoji.
- No notifications between milestones. The app is silent until your next checked hour.
- No widgets, no Wear OS, no lock-screen complications. The notification IS the widget.
- No CSV export. There's nothing to export.
- No dark-mode toggle. Theme follows brightness automatically.
- No onboarding. The home screen is the onboarding.
- No analytics. Not even crash reporting.
- No landscape mode. Portrait only — this is an instrument, not a chart.
If you find yourself missing one of these, the answer is almost certainly that you're trying to use Interfast as a tracker. Use a different app for that — they're abundant and well-funded.
A milestone notification is the entire UI surface during the 99% of the day when you're not in the app. So it's where most of the design effort went.
- Backdrop: a programmatically rendered bitmap — drawn at 200×100 with anti-aliasing off, Floyd–Steinberg-dithered to a 9-color palette, then upscaled 4× nearest-neighbor for the OP-1 LCD look. Void-black, dot-matrix grid, condensed-bold numerals, a 24-segment progress strip at the bottom (lit to the hour reached). The bitmap carries no words: at that resolution type dithers into noise, so the system header and title overlay do the talking.
- Layout: full-bleed image with a top gradient scrim and the title + body overlaid in white mono caps — anchored top so the segment strip stays visible.
- Action: a single
STOPbutton that cancels every remaining milestone. No confirmation dialog. The final milestone has no STOP — nothing left to stop; it reads "tape rewound. Eat well." - Tap anywhere: opens the app.
Implementation: NotificationCompat.DecoratedCustomViewStyle + setCustomBigContentView(RemoteViews). Collapsed and heads-up views use the system default — OEM shades crop custom heads-up layouts unpredictably, and a cropped poster is worse than no poster.
| Datum | Where it lives |
|---|---|
| Selected start time | DataStore (device only) |
| Checked milestone hours | DataStore (device only) |
| Active state | DataStore (device only) |
| Scheduled triggers | AlarmManager (device only) |
| Anything else | not collected |
There is no network code in this app. There is no SDK. There is no telemetry. The Android INTERNET permission is not declared.
- Kotlin · Jetpack Compose · Material 3
DataStorefor persistenceAlarmManager.setExactAndAllowWhileIdlefor milestone scheduling (withsetAndAllowWhileIdlefallback when exact-alarm permission isn't granted)BroadcastReceivertriplet: milestone → notification → STOP / boot- and update-replay (alarms survive reboots and app updates viaMY_PACKAGE_REPLACED)- No DI framework. A tiny ServiceLocator on
InterfastApplicationexposes the repository and scheduler. - No Hilt, no Room, no WorkManager, no Glance. (We removed all four during the rebuild.)
./gradlew :app:installDebugJDK 17. Android SDK 34. minSdk 26.
app/src/main/java/com/interfast/
├── InterfastApplication.kt ServiceLocator: scheduleRepository + alarmScheduler
├── MainActivity.kt the card flip: front (deck) ↔ rear (manual)
├── alarm/
│ ├── AlarmScheduler.kt wraps AlarmManager.setExactAndAllowWhileIdle
│ ├── FastNotificationReceiver.kt fires the notification; auto-disarms after the last milestone
│ ├── StopActionReceiver.kt STOP action — cancels later milestones
│ ├── BootReceiver.kt re-registers alarms after reboot or app update
│ ├── NotificationArt.kt dithered low-res banner renderer
│ ├── NotificationChannels.kt
│ └── EasterEgg.kt ×5
├── data/ScheduleRepository.kt DataStore-backed ScheduleState
└── ui/
├── theme/ Color, Type, Theme, AmbientLight
├── rear/RearPanel.kt the printed back: silkscreen diagram + manual
├── components/InterfastButton.kt
└── scrubber/
├── ScrubberScreen.kt the front: the entire deck UI
├── ScheduleViewModel.kt
└── Pieces.kt BrandHeader, HeroTitle, IndexedHourRow, …
More docs: PRINCIPLES.md (the one-page law) · USER_GUIDE.md · CHANGELOG.md
- Teenage Engineering OP-1 — the tape transport metaphor for the scrubber, the giant numerical readouts, the LED pip indicators, the "instrument, not a screen" feel.
- Nothing Phone / Nothing OS — dot-matrix textures, monospace data labels, the discipline of a single accent color (Glyph Red).
- Müller-Brockmann · Hofmann · Weingart — Swiss modular grid, bold display type, deliberate diagonal grid breaks, edition / serial-number marks as graphic elements.
- BJ Fogg, Tiny Habits — friction at the decision point is the enemy of a habit; remove every step that asks the user to decide.
- James Clear, Atomic Habits — make the cue obvious (the milestone notification), make the action satisfying (the tactile setup), make the reward immediate (the body's own feedback).
- Jason Fung, The Obesity Code / The Complete Guide to Fasting — the biology of the milestone hours; the case for fasting as practice rather than performance.
Apache 2.0. See LICENSE.
Interfast is a single-screen Android app. The goal of the project is to remain a single screen. (The back of the screen is print, not a screen. It doesn't count.)