21:3 Fasting Schedule with an Evening Start
A 21:3 fasting schedule means fasting for 21 hours and eating during a 3-hour window. For evening starts, one simple version is to start fasting at 7:00 PM and break the fast at 4:00 PM the next day.
A sample 21:3 day
Who 21:3 fits
Common mistakes
Track 21:3 in Fast Goblin
Set your goal to 21 hours, tap start, and watch the ring fill. Streaks, history, and home-screen widgets keep you on rhythm — all private on your iPhone.
21:3 questions
Yes — black coffee, plain tea, and water won't break a 21:3 fast. Skip milk, sugar, and sweeteners.
No problem. End the fast, log it, and start fresh tomorrow. Consistency over weeks matters more than any single day.
Use this page as a practical 21:3 schedule starter. It is built for people who finish dinner and want the fast to start automatically from that point, with a sample clock window and simple tracking advice.
21:3 schedule at a glance
| Window | Time | What it means |
|---|---|---|
| Start fasting | 7:00 PM | Finish your last meal and start the timer. |
| Break fast | 4:00 PM | Your 21-hour fast is complete. |
| Eating window closes | 7:00 PM | Finish meals before the next fast starts. |
Who this schedule fits
This is useful if dinner is the natural end of your eating day and you want the app to remember the window for you.
Common mistakes
- Choosing a window that looks perfect online but does not fit your actual day.
- Forgetting to start the timer after dinner and guessing later.
- Making the schedule stricter before the easier version feels automatic.
- Treating one missed day as proof the routine failed.
How to track it
Fast Goblin can make this 21:3 schedule easier by saving the window, showing current progress, and helping you start the next fast without doing time math again.
Safety note
Fast Goblin is a tracking app, not medical advice. Intermittent fasting is not for everyone; people who are under 18, pregnant or breastfeeding, have a history of eating disorders, or use insulin/diabetes medication should talk to a qualified professional before changing fasting routines.
How Fast Goblin helps
Fast Goblin can make this 21:3 schedule easier by saving the window, showing current progress, and helping you start the next fast without doing time math again.
Questions
It can be useful if the timing fits your real routine. Start with the sample window and adjust the start time if your meals happen earlier or later.
A common option is 7:00 PM, but the best start time is the one you can repeat consistently.
Yes. The plan is the fasting/eating duration, not one fixed clock schedule.
Run 21:3 the easy way.
Free on the App Store, private by design. Android coming soon.