By ONE Editorial Team · Published: September 4, 2026
An intermittent fasting schedule defines the hours you spend fasting and the hours when you eat. Common daily schedules range from 12:12 to 20:4, while weekly approaches such as 5:2 use a different structure.
There is no single schedule that is right for everyone. The most practical option is usually one that fits your routine, nutrition needs, and ability to stay consistent.
| Schedule | Fasting window | Eating window | Example |
|---|---|---|---|
| 12:12 | 12 hours | 12 hours | 7 PM → 7 AM |
| 14:10 | 14 hours | 10 hours | 7 PM → 9 AM |
| 16:8 | 16 hours | 8 hours | 8 PM → 12 PM |
| 18:6 | 18 hours | 6 hours | 8 PM → 2 PM |
| 20:4 | 20 hours | 4 hours | 8 PM → 4 PM |
These examples show one possible way to place each fasting window. The same fasting duration can be scheduled at different times of day.
An intermittent fasting schedule is simply a recurring pattern of fasting windows and eating windows. It defines when you eat rather than dictating what to eat, so nutrition quality within the eating window still matters.[1]
The same fasting duration can be arranged at different times of day. A 16-hour fast can begin after an early dinner and end at noon the next day, or it can begin after a late dinner and end in the afternoon. What defines the schedule is the length of the fasting and eating windows, not the exact clock time.
A large part of a daily fasting window typically overlaps with sleep, which makes shorter and moderate schedules more practical for many people. Alongside daily time-restricted eating, other approaches — including weekly patterns such as 5:2 — use a different structure and are covered further below.[2]
For a broader overview of the practice itself, see our guide to what intermittent fasting is and how it works.
A 12:12 schedule splits the day into a 12-hour fasting window and a 12-hour eating window. A common example is eating between 7:00 AM and 7:00 PM, then fasting until 7:00 AM the next day.
12:12 is a relatively small departure from a typical overnight fast, which makes it an approachable pattern for people who want structure without a large adjustment. It often fits family meals, social routines, and normal work hours with little disruption.
Note on ONE: ONE Intermittent Fasting App can be used to set custom fasting durations, but fasting sessions of 12 hours or less are not saved to fasting history.
A 14:10 schedule uses a 14-hour fasting window and a 10-hour eating window. A common example is eating between 9:00 AM and 7:00 PM, then fasting until 9:00 AM.
14:10 is more restrictive than 12:12 but still leaves a relatively broad eating window, which many people find easier to sustain than 16:8. It is often used as a stepping stone before extending the fasting window further.
14:10 can be tracked in ONE using the Custom Timer.
A 16:8 schedule pairs a 16-hour fasting window with an 8-hour eating window. It is one of the most widely discussed time-restricted eating patterns in the popular literature.[2]
Practical examples vary. Eating between 12:00 PM and 8:00 PM (skipping breakfast) is common, but eating between 8:00 AM and 4:00 PM (skipping dinner) is another way to structure the same 16-hour fast. The right placement depends on your work, sleep, and social schedule.
Note on ONE: ONE includes a 16-hour Quick Start timer if you want to track a 16-hour fasting window.
An 18:6 schedule uses an 18-hour fasting window and a 6-hour eating window. A common example is eating between 1:00 PM and 7:00 PM, then fasting until 1:00 PM the next day.
A narrower meal window can be harder to fit around work and social meals, and it leaves less time to eat enough nutritious food. Adequate energy and protein intake within a shorter eating window become more important. Some people move from 16:8 to 18:6 gradually rather than starting there.
18:6 is not a named Quick Start preset in ONE. It can be tracked with the Custom Timer.
A 20:4 schedule uses a 20-hour fasting window and a 4-hour eating window. A common example is eating between 4:00 PM and 8:00 PM, then fasting the remaining 20 hours.
A four-hour eating window is significantly narrower than the more common options above. It can be difficult to sustain, and it can make it harder to consume enough food to meet daily energy and protein needs. Longer fasting windows are not automatically more effective.
20:4 is not a named Quick Start preset in ONE. It can be tracked with the Custom Timer.
5:2 fasting is a weekly pattern rather than a daily one. In a typical setup, people eat normally on five days and substantially reduce calories on two non-consecutive days (often around 500–600 kcal). Because it is not defined by a daily fasting/eating hour split, it does not map neatly onto the table above.[2]
OMAD (“one meal a day”) compresses all daily energy intake into a single meal. This produces a very narrow eating window and a long daily fast. It is more restrictive and is not necessary to succeed with intermittent fasting.
Neither 5:2 nor OMAD is a named Quick Start preset in ONE.
The most useful schedule is usually the one you can follow consistently. A few practical factors help narrow the choice:
The most restrictive schedule is not automatically the most effective or appropriate. Some people prefer to begin with a less restrictive window and adjust gradually based on how they feel; others prefer to stay with a moderate schedule long-term.[1]
The same fasting duration can be scheduled at very different times of day. Two versions of a 16:8 schedule illustrate the point:
Earlier window
Eat 8:00 AM – 4:00 PM
Fast from 4:00 PM until 8:00 AM the next day. Often called early time-restricted eating.
Later window
Eat 12:00 PM – 8:00 PM
Fast from 8:00 PM until noon. A common pattern for people who skip breakfast.
Practical considerations usually matter more than a preference for one particular placement. Family meals, work hours, sleep, and training timing all influence which window is realistic for a given person. Some research has examined earlier time-restricted eating in specific populations, but this page is not the right place to draw broad circadian conclusions — adherence and fit tend to matter most in real-world routines.
“Intermittent fasting schedule” is a broad term. It can refer to a recurring daily pattern or to a weekly pattern that varies from day to day.
Daily time-restricted eating
Weekly approaches
Daily patterns keep the fasting and eating windows the same each day; weekly patterns keep the timing looser during the week but restrict calories on specific days. Neither category is inherently better — they suit different lifestyles.
ONE is an intermittent fasting app for iOS and Android. Its fasting timer helps you track any fasting schedule you choose. Quick Start buttons cover the most common durations, and a Custom Timer covers the rest.
Timer & core tracking (Free)
Premium features
What ONE tracks and what it does not
Educational schedules such as 14:10, 18:6, or 20:4 are not separate named Quick Start presets in ONE. You can track them with the Custom Timer. ONE saves completed fasting sessions longer than 12 hours to your fasting history; sessions of 12 hours or less are not saved.
Not automatically. A longer fasting window is more restrictive, tends to be harder to sustain, and leaves less time to eat enough nutritious food. Systematic reviews of intermittent fasting generally show that outcomes depend on adherence and overall energy intake — not on the extremity of the schedule alone.[3]
For most practical goals, a schedule that a person can maintain consistently over months tends to matter more than a schedule that is technically longer but only followed occasionally.
Any change to eating patterns should account for individual health context. Professional guidance is especially important for people who:
Important
ONE is a fasting and wellness tracking tool. It does not diagnose, treat, or replace advice from a qualified healthcare professional.
There is no single easiest schedule for everyone. Many people find 12:12 or 14:10 relatively straightforward because a large part of the fasting window overlaps with sleep. The right starting point depends on your normal routine, hunger tolerance, and how quickly you want to adjust.
16:8 means fasting for 16 hours per day and eating within an 8-hour window. A common example is eating between 12:00 PM and 8:00 PM, then fasting until noon the next day, though the same 16-hour duration can be scheduled at different times of day.
Yes. 14:10 — fasting for 14 hours and eating within a 10-hour window — is a form of time-restricted eating, which is a common category of intermittent fasting. It is less restrictive than 16:8 or 18:6.
Not necessarily. 18:6 is more restrictive than 16:8 — a longer fasting window and a shorter eating window — but more restrictive is not the same as better. Adherence and how well a schedule fits your life often matter more than the exact number of hours.
You can, and many people do adjust their window around work or social meals. Large day-to-day swings can make the routine harder to sustain, but small adjustments are generally fine.
A 20:4 schedule is more restrictive and may not be appropriate for everyone. It leaves only four hours for meals, which can make adequate nutrition harder. Anyone with a medical condition, on medication, pregnant or breastfeeding, or with a history of an eating disorder should speak with a healthcare professional first.
Yes. ONE includes Quick Start durations of 16, 19, 24 and 36 hours, plus a Custom Timer that lets you set any duration you like. Schedules such as 14:10, 18:6 or 20:4 are not separate named Quick Start presets — they can be tracked with the Custom Timer.
No. Fasting sessions of 12 hours or less are not saved to your fasting history in ONE. Longer completed fasting sessions are saved.
Prepared by the ONE Editorial Team using guidance from established medical institutions and peer-reviewed research.