FastOn

A fasting timer that shows what's happening inside — fat burning, ketosis, autophagy in real time. Widget & Live Activity. Fully offline, no sign-up.

A fasting timer that lets you see what's happening inside your body — even without opening the app.

FastOn helps you keep a 16-hour intermittent fast with a clean, focused timer. It works fully offline, needs no account, and keeps all your data on your device.

VISUALIZE YOUR FAST As time passes, FastOn shows what's happening inside your body in real time: Digesting → Blood sugar → Fat burning → Ketosis → Autophagy → Growth hormone → Deep repair It's not just a countdown — knowing "fat burning starts soon" is what keeps you going. Tap any stage to learn the science behind it and what benefits to expect.

FREE FEATURES

• Start/stop a fast in one tap (backdate from your last meal)
• Circular timer + real-time body stage
• 16:8 plan
• Streak tracking
• Last 7 days of history
• Water intake tracker
• Mood & energy self-logging
• Confetti celebration + SNS share card on completion

PREMIUM

• All plans (18:6 / 20:4 / OMAD / 5:2 / Custom)
• Home screen Widget + Live Activity (remaining time & stage on Lock Screen and Dynamic Island)
• Full statistics + insights
• AI Advice (personalized tips based on your fasting patterns)
• Weight tracking + goal weight line + HealthKit
• 20 badges / achievements with categories
• CSV data export
• Eating window end & streak crisis notifications
• No ads

NOTE This app does not provide medical advice. Body-stage information is a general guideline based on common scientific knowledge and varies by individual. If you have a medical condition or are pregnant, please consult your doctor.

SUBSCRIPTION

• Monthly ¥480 / Yearly ¥2,900 (yearly includes a 7-day free trial)
• Payment is charged to your Apple ID at confirmation.
• It renews automatically unless auto-renew is turned off at least 24 hours before the end of the period.
• Manage or cancel in Settings > Apple ID > Subscriptions.

Terms of Use and Privacy Policy are available in the app settings and from the store links.