20:4 intermittent fasting
A 20-hour fast with a 4-hour eating window — an advanced protocol sometimes called the Warrior Diet.
20h
Ayuno
4h
Ventana de alimentación
Horario de ejemplo
Eating window opens at 4:00 PM
Start your first meal of the day.
Eating window closes at 8:00 PM
Finish your last meal for the day.
Fast until 4:00 PM the next day
20-hour fasting window begins.
Para quién es adecuado
- Experienced fasters who have adapted to 16:8 or 18:6
- People comfortable eating one large meal and a smaller meal per day
- Those who prefer eating in the evening
Pros and cons
Ventajas
- Provides an extended fasting period that many advanced practitioners prefer
- Simplifies the day — fewer meals to plan and prepare
- May help some people focus on eating nutrient-dense foods due to the narrow window
Desventajas
- Fitting adequate nutrition into 4 hours can be challenging
- Very restrictive for social eating — most social meal occasions fall outside a narrow window
- Not suitable as a starting point for people new to intermittent fasting
Preguntas frecuentes
- What is the Warrior Diet and is it the same as 20:4?
- The Warrior Diet, popularised by Ori Hofmekler, involves a 20-hour fasting window with small amounts of raw fruits and vegetables allowed, followed by a 4-hour evening eating window. 20:4 fasting typically refers to the same window structure, though strict interpretations vary on what is permitted during the fasting hours.
- Is 20:4 safe for beginners?
- 20:4 is generally considered an advanced fasting schedule. Most practitioners and nutritional guidance suggest adapting to shorter fasting windows — such as 16:8 or 18:6 — before attempting a 20-hour fast. Anyone with underlying health conditions should consult a clinician first.
- How do I get enough nutrients in a 4-hour eating window?
- Prioritising calorie-dense, nutrient-rich foods — such as lean proteins, whole grains, healthy fats, and vegetables — can help meet nutritional needs in a compact window. Some people find it easier to have one larger meal and one smaller snack within the 4-hour period.