Vastenschema's

16:8 Intermittent Fasting

16h / 8h

16:8 fasting is the most popular intermittent fasting protocol — fast for 16 hours, eat within an 8-hour window. It's beginner-friendly because the fast covers the time you're already sleeping, and most people land in mild ketosis right at the end of the fasting window.

18:6 Intermittent Fasting

18h / 6h

18:6 extends the daily fast by two hours, deepening ketosis and pushing growth hormone higher. It's the natural next step for someone who has been doing 16:8 for a few weeks and wants more metabolic benefit without committing to OMAD.

20:4 Intermittent Fasting (Warrior Diet)

20h / 4h

20:4 — sometimes called the Warrior Diet — fasts for 20 hours and concentrates eating into 4. It's an advanced protocol best attempted after weeks of 18:6. The metabolic benefits are real, but so is the difficulty of meeting protein and energy needs in such a tight window.

One Meal A Day (OMAD)

23h / 1h

OMAD compresses all daily eating into one meal — typically a 23:1 schedule. It's simple, requires zero meal planning beyond one large dinner, and brushes the edge of where mild autophagy starts. It's also the easiest IF protocol to under-fuel on, so structure matters.

5:2 Intermittent Fasting

24h / 0h

5:2 is technically modified fasting rather than a true fast: five days of normal eating and two non-consecutive days at ~500 kcal (women) or ~600 kcal (men). It's gentler than full extended fasting, easier to fit around social life, and well-studied for metabolic benefits.

Eat-Stop-Eat (24-hour fasts, 1–2× per week)

24h / 0h

Eat-Stop-Eat means doing one or two complete 24-hour fasts each week with normal eating in between. It's structurally simple and pulls you firmly into ketosis without the daily commitment of OMAD or 20:4. Best run dinner-to-dinner so you never spend a full waking day fasted.

24-Hour Fast

24h / 0h

A 24-hour fast is the threshold where extended-fasting benefits begin. You'll cross into mild ketosis around hour 16–18, see growth hormone climb, and brush the start of autophagy right at the 24-hour mark. It's a manageable first extended fast for most healthy adults.

36-Hour Fast (Monk Fast)

36h / 0h

The 36-hour fast — sometimes called the Monk Fast — pushes you firmly into deep ketosis and full autophagy. It's a single overnight fast extended through one full day plus a second night. Done weekly or biweekly, it captures most of the metabolic benefit of longer fasts at a fraction of the difficulty.

48-Hour Fast

48h / 0h

A 48-hour fast doubles the autophagy window of a 24-hour fast and starts dropping inflammation markers. It's a serious commitment — two days without food — but the metabolic and cellular benefits are well documented. Done once a month, it's a high-leverage protocol.

72-Hour (3-Day) Fast

72h / 0h

The 72-hour fast crosses into immune-regeneration territory — by hour 72 your body is recycling old white blood cells and beginning to renew the immune profile. It's the threshold where the deepest fasting benefits appear. It's also serious: 3 days without food demands real preparation, hydration, and a careful refeed.