What intermittent fasting actually means
Intermittent fasting (IF) is not a diet — it is a schedule. You alternate a fasting window (water, plain tea, or assisted electrolytes) with an eating window where you eat normal low-carb meals.
Dr. Eric Westman points out that on a well-formulated ketogenic diet, hunger often drops within days, so many people naturally skip breakfast without forcing it. That is intermittent fasting emerging from reduced appetite, not willpower alone.
16:8 — the beginner standard
Sixteen hours fasting, eight hours eating. Example: finish dinner at 7 PM, eat again at 11 AM. Dr. Mindy Pelz uses 13–16 hour fasts as the baseline for metabolic flexibility — accessible to nearly everyone.
Benefits: easier socially, fits most work schedules, enough time to shift toward fat burning (often by 12–14 hours). Good first step if you are new to fasting or managing insulin resistance cautiously.
18:6 — a modest step up
Eighteen hours fasting, six hours eating. You push closer to the 17-hour autophagy threshold Dr. Mindy discusses without committing to a full 24-hour fast.
Best for: people comfortable with 16:8 for several weeks, stable energy, and no signs of excessive stress (poor sleep, hair loss, anxiety). Cycling women should avoid pushing to 18:6 during ovulation (days 11–15) — keep to 15 hours max in that window.
OMAD and longer fasts — not step one
One meal a day (OMAD) and fasts beyond 18 hours are advanced. Dr. Boz warns that people with severe insulin resistance may not be "healthy enough to fast" until they stabilize with low-carb eating first — glucose can stay elevated for days on extended fasts.
Build the habit: 16:8 for 2–4 weeks → try 18:6 → consider 24-hour gut resets occasionally. Use our fasting clock to track phases and break-fast guidance.