ZeroHourInstall

For Android · Material 3 Expressive

Watch your body change, hour by hour.

ZeroHour is an intermittent fasting timer that announces every phase of your fast as your body crosses into it — fed, fat burning, ketosis, autophagy, deep autophagy, and growth hormone.

Install free See the six phases

Free · $1.99 Pro · No subscriptions · No accounts

The journey of a 48-hour fast

00h

Fed

You just ate. Insulin is up.

Your body is busy digesting and storing nutrients. ZeroHour starts the clock the moment you do.

12h

Fat Burning

Glycogen runs low. Fat goes first.

Around hour twelve, your reserves are drained and the body shifts to burning stored fat. ZeroHour announces the crossing.

14h

Ketosis

Ketones start. Focus sharpens.

The liver begins producing ketones for fuel. Mental clarity sharpens, cravings level off. You feel different.

16h

Autophagy

Cells start cleaning house.

Damaged proteins and dead organelles get broken down and recycled. This is the bit most people fast for.

24h

Deep Autophagy

A day in, renewal compounds.

Stem-cell activity is reported to climb, growth hormone starts rising. The body is rebuilding from the inside.

48h

Growth Hormone

Two days in, HGH peaks.

Growth hormone climbs to its highest natural levels. Lean mass is preserved while fat oxidation continues.

Custom plans (Pro)

Or set your own clock. And your own stages.

Not everyone fasts on the same schedule. Pick a preset, or set your own — any duration, any phase thresholds. If you cross into ketosis at hour eleven, set it there.

16h → 72h

Any duration

6 stages

Any thresholds

Custom plan

Editing

Total duration50h 00m

Phase thresholds

  • Fed0h
  • Fat Burning11hedited
  • Ketosis15hedited
  • Autophagy20hedited
  • Deep Autophagy32hedited
Start fast

Inside the app

A look around. Seven screens.

Timer, stats, history, achievements, lock-screen notification, and a choice of colour themes via Material You.

01Timer
Timer

Hour-by-hour phase ring.

02In Progress
In Progress

Mid-fast in Fat Burning.

03Stats
Stats

Weekly snapshot + weight.

04History
History

Every fast you've finished.

05Achievements
Achievements

Eleven small honours.

06Lock Screen
Lock Screen

Live notification + Now Bar.

07Themes
Themes

Dynamic Color + true black.

Pricing

Free forever. Pro is $1.99, once.

No subscriptions. No accounts. The free tier is generous on purpose; Pro covers extended fasts, custom plans, and exports.

FreeOne-time

$0

Forever — with a single, small ad

  • All standard plans (16:8, 18:6, 20:4, OMAD)
  • Six phases with real-time tracking
  • Streaks, achievements, weight tracking
  • Stats dashboard with charts
  • Milestone notifications + live countdown
Install free
Recommended
ProOne-time

$1.99

One-time in-app purchase

  • Extended plans (36h · 48h · 72h)
  • Custom plans with custom phase thresholds
  • Data export (JSON · CSV)
  • Ad-free
  • Lifetime access to every future Pro feature
Upgrade in-app

Built for Android

Native, top to bottom.

Material 3 Expressive

Latest Material design language, end to end.

Dynamic Color

Palette blends with your wallpaper on Android 12+.

Live Notification

Phase + countdown stay on your lock screen.

Now Bar (Android 16+)

Surface phase + countdown in the system Now Bar.

20 Languages

Localised by humans — Arabic, Hindi, German, Japanese, more.

Modern Kotlin

Jetpack Compose · Room · MVVM. Fast, battery-light.

Start tonight.

Free to install. Free to use. Pro is $1.99 — paid once, when you're ready.

Get it on Google PlayNo accounts · Yours forever