Every intermittent fasting schedule is the same idea with a different dial setting: pick a window, eat inside it. What changes is how tight the window is and how much of your ordinary life has to bend around it.
Here is the whole set, honestly compared.
The schedules
| Schedule | Fast | Eat | Realistically |
|---|---|---|---|
| 12:12 | 12h | 12h | Barely a change. A good first week. |
| 14:10 | 14h | 10h | Skip breakfast or eat dinner early. Easy. |
| 16:8 | 16h | 8h | The standard. Two solid meals. |
| 18:6 | 18h | 6h | A step up. Meals get closer together. |
| 20:4 | 20h | 4h | Hard to eat enough. Not a starting point. |
| OMAD | ~23h | ~1h | One meal. A different discipline entirely. |
| 5:2 | 2 days at ~500–600 cal | 5 normal days | Not a daily window at all. |
The ones worth your time
12:12 is where you start if you have never done this, no matter how confident you feel. It costs almost nothing — finish dinner at 8pm, eat again at 8am — and it tells you how your body responds before the stakes rise.
14:10 is the sweet spot people skip past. It gets you most of the metabolic shift, and it survives a dinner invitation.
16:8 is the default for good reason. See what is 16:8 fasting for the detail. Eight hours is enough for two real meals, and sixteen reliably clears the point where liver glycogen runs low for most people.
18:6 is a reasonable progression if 16:8 has become genuinely effortless. It is not better, it is tighter. Diminishing returns start around here.
The ones to be careful with
20:4 and OMAD compress eating so hard that hitting your protein and micronutrient needs stops being automatic and starts being a project. People lose weight on these partly because they under-eat by accident, which is not the same as a schedule working. OMAD, honestly assessed goes into this properly.
5:2 is a different animal — two non-consecutive days at roughly 500–600 calories, five normal days. It is not a daily eating window and it does not produce a daily fasting rhythm. Some people find two hard days easier than a permanent habit change. Others find that two hard days dominate the week. It is genuinely a temperament question. Fastrackie doesn't ship a 5:2 plan: it times fasts, and a 500-calorie day isn't one.
How to actually choose
Pick the tightest schedule you would still be doing in three months on a bad week. Not your best week — a bad one, with a late meeting and a birthday dinner.
That is the whole method. A 16:8 you keep beats an OMAD you abandon in nine days, and the metabolic difference between them is much smaller than the adherence difference.
Moving between them
Ramp up, do not jump. A reasonable path:
- Two weeks at 12:12.
- Two weeks at 14:10.
- Settle at 16:8, or stay at 14:10 if that is where it feels sustainable.
Move the window earlier or later freely — an 11am to 7pm window and a 1pm to 9pm window are the same schedule. Shifting by two hours on a Friday is not breaking anything.
What none of them change
No schedule here tells you what to eat, and none of them makes a poor diet good. They also do not stack: doing 18:6 does not make you more disciplined than someone on 14:10, it makes your eating window shorter.
If a schedule starts producing guilt, preoccupation with food, or a feeling that breaking the fast is losing, that is the signal to loosen it. See how to break a fast.
Before you start any of them
Do not start if you are pregnant or breastfeeding, if you have a history of disordered eating, if you are under 18, or if you have type 1 diabetes. Talk to a clinician first if you have type 2 diabetes, low blood pressure, or take medication that must be taken with food.