FastFlex: Fasting & Autophagy

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Content rating
Everyone
10+
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Content rating
Everyone
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About this app

FastFlex is an intermittent fasting timer and fasting tracker that shows, live, which phase your body is likely in: digesting, sugar-burning, fat-burning, ketosis and autophagy. The timing is personalised, so your fasting phases follow your body rather than a generic chart.

This app is not a medical device and does not diagnose, treat, cure or prevent any condition. It gives general educational estimates about fasting. Speak to a qualified healthcare professional before fasting, especially if you are pregnant, breastfeeding, under 18, have a medical condition, or take medication for diabetes such as insulin, sulfonylureas or SGLT2 inhibitors.

YOUR FASTING PHASES, PERSONALISED
Most fasting timers show everyone the same chart. FastFlex estimates your phases from what you tell it: the carbs and protein in your last meal, alcohol, your activity, age, sex and body composition. Walks and workouts during a fast pull your phase lines earlier, live. Black coffee and plain green tea can nudge fat-burning earlier too.

FEATURES
- Fasting timer with a progress ring, projected end time and five live phase lanes.
- Intermittent fasting plans: 16:8, 14:10, 18:6, 20:4 and OMAD, plus 24, 30 and 36-hour fasts, an open-ended fast and a custom-plan builder.
- Cell Repair Score: an estimated A to F signal of how strong and consistent your fasting has been over the last 20 days, with a clear explainer.
- Weekly autophagy time, energy burned during each fast, and a smoothed weight trend.
- Weight from smart scales and steps through Health Connect, or enter them yourself.
- Quick exercise logging with a timer: push-ups, squats, planks, stretching and more.
- Optional pre-fast check-in for carbs, protein, sleep, stress and mood.
- Eating-window log: note what you eat and its calories, if you want to.
- Evidence-graded library of compounds such as green tea, berberine and spermidine, with safety notes.
- Help with fasting headaches and low energy, starting with salt and water.
- Calendar of every fast: edit it, resume it, or add a fast you did away from the app.
- Trends: longest streak, completion rate, averages, weekly autophagy time and your Cell Repair Score over time.
- Reminders you choose, including when your fast completes.
- Forgiving streaks: a missed day never erases your longest run.
- A kind coach you can turn down or off. Light, dark or system theme.

HONEST BY DESIGN
Fasting phases, ketosis, autophagy and the Cell Repair Score are modelled estimates based on published research, not measurements. Autophagy cannot be measured at home, and FastFlex never pretends otherwise.

YOUR DATA
There is no account. Your fasts, check-ins and weight are stored on your phone and are deleted when you uninstall. Health Connect access is read-only. FastFlex shows ads from Google AdMob at the bottom of the screen, never over your timer. AdMob uses your device's advertising ID, as explained in our privacy policy and the Data safety section. In the UK and EU you can change your ad privacy choices in Settings.
Privacy policy: https://AShana9.github.io/fastflex-legal/
Intermittent fasting timer showing your phases: fat-burning, ketosis, autophagy
Updated on
Sep 30, 2026

Data safety

Safety starts with understanding how developers collect and share your data. Data privacy and security practices may vary based on your use, region, and age. The developer provided this information and may update it over time.
  • This app may share these data types with third parties
    Location, App activity and 2 others
  • This app may collect these data types
    Location, App activity and 2 others
  • Data is encrypted in transit
  • Data can’t be deleted

What’s new

- Contact us and Rate FastFlex, now in Settings
- Clearer FastFlex Plus page; Restore purchases now tells you what it found
- Easier first-time setup, fixes and small improvements