14:10, 16:8, 18:6, 20:4, OMAD: what the numbers mean
Fasting plans are usually written as two numbers separated by a colon. The first is the number of hours without eating. The second is the length of the eating window. Together they make twenty-four.
The daily plans
| Plan | Hours fasting | Eating window |
|---|---|---|
| 12:12 | 12 | 12 |
| 14:10 | 14 | 10 |
| 16:8 | 16 | 8 |
| 18:6 | 18 | 6 |
| 20:4 | 20 | 4 |
| OMAD | about 23 | one meal |
12:12 is close to an ordinary day with no late snack: dinner at 19:30, breakfast at 7:30.
14:10 and 16:8 move the first meal later or the last meal earlier. 16:8 is the schedule most people mean when they say intermittent fasting. Here is how to place a 16:8 window.
18:6 and 20:4 shorten the window to two meals, or one meal and a snack.
OMAD stands for “one meal a day”.
The US National Institute on Aging groups these daily schedules under the name time-restricted feeding: meals are taken within a limited number of hours each day.
Other patterns you may read about
Some patterns count in days, not hours. 5:2 means eating as usual five days a week and very little on two. Alternate-day fasting switches between the two every other day. They are different methods with different constraints, and they are not daily timers.
Longer is not better
The numbers describe a timetable, not a ranking. A shorter window is harder to fit around work, family and sleep, and it is not a goal in itself. Research on people is still limited: the National Institute on Aging notes that there is not enough evidence to recommend any of these eating patterns to the public.
Fasts longer than a day are a different matter and should be discussed with a doctor first. Volvelle shows a warning beyond 24 hours and does not allow plans longer than 72 hours.
Tracking a plan
A plan needs two things from a tracker: the time your fast began, and the time it is due to end. Everything else follows. Volvelle offers the six plans above, custom plans, and a weekly schedule if your days differ.
Before choosing a plan, read who should talk to a doctor before fasting.
Source
- National Institute on Aging, Calorie restriction and fasting diets: what do we know?, consulted on 10 November 2026.
This guide is general information, not medical advice. Talk to a doctor before you start fasting.