16:8 means 16 hours without calories and an 8-hour eating window. It is the most widely used intermittent fasting schedule because it fits work, family dinners, and social life better than stricter protocols.
Sample 16:8 schedules
Lunch-led window (popular): Fast 20:00 → 12:00. Eat 12:00–20:00.
Early bird window: Fast 18:00 → 10:00. Eat 10:00–18:00. Works if you prefer bigger breakfasts and no late eating.
Family dinner window: Fast 21:00 → 13:00. Eat 13:00–21:00. Good when evenings are your main social meal time.
Pick one and hold it for at least two weeks before judging results.
What happens hour by hour (simplified)
- Hours 0–4 after last meal: Digestion; insulin elevated then falling.
- Hours 4–12: Glycogen use; hunger may peak then often eases.
- Hours 12–16: Fat oxidation increases for many people; mental clarity sometimes improves once adapted.
Individual variation is huge. Do not treat this as a precise timeline—use it to understand why the first few hours feel hardest.
What to eat in the 8-hour window
16:8 works best with two or three structured meals—not constant snacking.
- Meal 1: Protein + vegetables + optional starch (e.g., chicken salad with rice).
- Meal 2: Similar structure; adjust carbs to activity level.
- Optional smaller meal/snack: Greek yogurt, fruit, or nuts if hunger demands it.
Aim for roughly 0.7–1 g of protein per pound of target body weight if fat loss is a goal (adjust for preference and medical advice).
16:8 and exercise
Many people walk or do light cardio fasted without issue. For heavy lifting or high-intensity sessions, try training after your first meal or mid-window and compare performance. There is no universal rule—only what you can sustain.
When to adjust or stop
Consider easing up if you have persistent fatigue, menstrual cycle disruption, sleep loss, or obsessive food thoughts. IF should simplify life, not dominate it. A 14:10 window or occasional non-fasting days may be smarter long term.
Related guides
- What Is Intermittent Fasting?
- Intermittent Fasting for Beginners
- Common Intermittent Fasting Mistakes
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