What intermittent fasting actually means
Intermittent fasting describes eating schedules that alternate periods of eating and not eating. Study protocols vary, so results from one schedule do not automatically apply to another.
Systematic reviews report that intermittent fasting can produce short-term weight loss, but it has not consistently outperformed continuous energy restriction and long-term evidence remains limited.
16:8 — the beginner standard
A 16:8 schedule allows eating during an eight-hour period. Example: finish dinner at 7 PM and eat again at 11 AM.
It may fit some schedules, but it is not accessible or beneficial for everyone. Research does not establish a universal hour when “fat burning” meaningfully begins.
18:6 — a modest step up
An 18:6 schedule narrows eating to six hours. No validated 17-hour autophagy threshold exists for humans.
There is not enough evidence to prescribe fasting length by menstrual-cycle phase. Stop and seek advice if fasting contributes to dizziness, sleep disruption, menstrual changes, anxiety, or restrictive eating.
OMAD and longer fasts — not step one
One-meal-a-day and longer fasts make it harder to meet energy and nutrient needs and may increase medication-related risks. They are not a required progression from shorter schedules.
Choose the least restrictive schedule that meets your goals, or do not fast. A timer records elapsed time; it does not determine safety or metabolic state.
Choosing your first IF window
If you have insulin resistance, read fasting with insulin resistance before tightening your window.
- Start 16:8 — skip breakfast, eat 12 PM–8 PM
- Move to 18:6 after 2–4 weeks if energy is stable
- Pair with low-carb macros for steadier glucose
- Track with our intermittent fasting timer