16:8 vs 18:6 vs OMAD — which fits you
There's no single "best" fasting schedule — only the one you'll actually keep. Here's who each protocol suits and how to step up without burning out.
16:8 — the gentle default
Fast 16 hours, eat within 8. It's the most popular starting point because it usually just means skipping breakfast and eating a normal lunch and dinner. Best for beginners, busy schedules, and anyone who wants results without a lifestyle overhaul.
18:6 — the natural step up
Fast 18 hours, eat within 6. A modest tightening of the window that many people move to once 16:8 feels automatic. Two solid meals still fit comfortably. Good for steady fat loss with a bit more fasting benefit.
20:4 — the "Warrior" window
Fast 20 hours, eat within 4. Now the window is tight, so meals need to be nutrient-dense to hit your protein and fibre. Suits experienced fasters who like structure and a strong appetite rhythm.
OMAD — one meal a day
Roughly a 23-hour fast around a single large, balanced meal. Simple by design, but it takes practice to eat enough quality food in one sitting. Best for experienced fasters who value simplicity over flexibility.
How to step up safely
- Only tighten the window once your current one feels easy for a couple of weeks.
- Move in one step (16:8 → 18:6), not two.
- Protect protein — a tighter window means each meal has to do more.
- Back off on hard-training or poor-sleep days. Fasting should flex with your life.
Not sure which to start with?
Kairo recommends a protocol from your goal and experience — and explains why.
Build my plan — freeGeneral information only, not medical advice. Consult a healthcare professional before starting any fasting routine, especially if you are pregnant, under 18, have a medical condition, or a history of disordered eating.