When should you eat on 16/8, 18/6 or 20/4 intermittent fasting?
Pick your fasting protocol and the time of your first meal, and we show you your exact eating and fasting windows. No mental maths: just read the schedule and you know when to start and when to stop. Fasting works through the discipline of the schedule, but what decides the result is still what you eat inside that window.
Guidance only. Intermittent fasting is not for everyone (pregnancy, diabetes, eating disorders, some medications): consult a professional.
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How is the fasting window calculated?
Intermittent fasting splits the day into an eating window and a fasting window. The calculator takes your protocol and the time of your first meal, and gives you the exact hours: when the window opens, when it closes, and when the fast ends. 16/8 is the most common because it fits an ordinary day — skip breakfast, eat between 12:00 and 20:00 — while 14/10 is gentler and 18/6 or 20/4 tighten it considerably. One thing worth being clear about: fasting is a schedule, not a mechanism. It helps people who find it easier to eat less within a window, and does nothing special for those who simply eat the same calories in fewer hours.
Intermittent fasting schedules by first meal
For each protocol (fasting hours : eating hours), the window you eat in if your first meal is at 8, 10, 12 or 2 pm. The rest of the day, until the next first meal, is fasting.
| Protocol | From 08:00 | From 10:00 | From 12:00 | From 14:00 |
|---|---|---|---|---|
| 14:10 | 08:00 – 18:00 | 10:00 – 20:00 | 12:00 – 22:00 | 14:00 – 00:00 |
| 16:8 | 08:00 – 16:00 | 10:00 – 18:00 | 12:00 – 20:00 | 14:00 – 22:00 |
| 18:6 | 08:00 – 14:00 | 10:00 – 16:00 | 12:00 – 18:00 | 14:00 – 20:00 |
| 20:4 | 08:00 – 12:00 | 10:00 – 14:00 | 12:00 – 16:00 | 14:00 – 18:00 |
| 23:1 | 08:00 – 09:00 | 10:00 – 11:00 | 12:00 – 13:00 | 14:00 – 15:00 |
Source: clock arithmetic with the same function as the calculator (first meal plus the window hours). Guidance only: fasting is not advised in pregnancy, with diabetes, with an eating disorder or with some medications. These are reference ranges for healthy adults, not a diagnosis or individual advice.
FAQ
What time do I eat on 16/8 if I start at 10 or 12?
If your first meal is at 10:00, your last one has to be before 18:00; if you start at 12:00, before 20:00. On 18:6, starting at 12:00 you close at 18:00, and on 14:10, at 22:00. The rest of the day is fasting.
What is 16/8 fasting?
Sixteen hours without eating and an eight-hour eating window, usually by skipping breakfast and eating between roughly midday and 20:00. Most of the fast is spent asleep, which is why it is the protocol people stick with for longest.
Does intermittent fasting help you lose weight?
It helps if it makes you eat less overall, and trials comparing it against continuous calorie restriction with the same deficit find similar results. So it is a useful tool for some people and irrelevant for others — there is no fat-burning switch that flips at hour 16.
What can I have during the fast?
Water, black coffee, plain tea and any zero-calorie drink. A splash of milk in coffee will not undo anything meaningful. What breaks the fast in a way that matters is anything with a real calorie load — juice, sugary drinks, or the biscuit that comes with the coffee.
Which fasting protocol should I choose?
The one that fits your life, because adherence is the whole point. If you are starting out, 14/10 is easy to hold. 16/8 is the usual middle ground. Tighter windows like 20/4 make it hard to hit your protein and are worth a specific reason before trying.
Keep reading
- The 16/8 intermittent fasting guide →
- Does fasted training burn more fat? →
- Does eating at night make you gain weight? →
- Caloric deficit for beginners →
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