Warrior Diet Plan (20:4)
The Warrior Diet is twenty hours of little or no food and a four-hour eating window in the evening, every day — the pattern Ori Hofmekler set out in his 2001 book. The window here opens at 4pm and closes at 8pm unless you move it. Pick your start date, the hour your window opens and the days you run it; the planner draws the week, prints it and puts every window in your calendar.
Four hours is one large meal and something either side of it, and at that length the schedule decides your day rather than fitting into it. The window has to sit where your evenings already are, which is why the planner starts from the hour you can actually eat and draws the rest of the week around it.
Check with a clinician first. Do not start the Warrior Diet if you are pregnant or breastfeeding, under 18, or have ever had an eating disorder. If you have diabetes or take insulin or any other medicine that lowers blood sugar, talk to your clinician before the first twenty-hour day. If you are new to fasting, start with a longer window and work down. Stop and eat if you feel faint, shaky or confused.
Your week
Plan your Warrior Diet week
Tap a day to change it.
- Mon5 Oct WindowEat 16:00 to 20:00
- Tue6 Oct WindowEat 16:00 to 20:00
- Wed7 Oct WindowEat 16:00 to 20:00
- Thu8 Oct WindowEat 16:00 to 20:00
- Fri9 Oct WindowEat 16:00 to 20:00
- Sat10 Oct WindowEat 16:00 to 20:00
- Sun11 Oct WindowEat 16:00 to 20:00
- Eating window
- 16:00–20:00
- Fast each day
- 20h
- Days on
- 7/7
- Fasting a week
- 140h
Every time here is a default until you change it, not a recommendation.
Take the plan with you
A plan on a web page is one you have to come back to. These two you keep: a sheet for the fridge and a calendar file for your phone. The file carries 4 weeks of days from your start date and refreshes every 24 hours, so a calendar that subscribes to its address never runs out.
If other people can see your calendar
Use the quiet version. It titles each day with plain words or the hours alone, and says nothing about fasting, calories or food anywhere in the file.
Subscribe rather than download
In Google Calendar choose "From URL"; in Apple Calendar choose File → New Calendar Subscription. Paste this address:
Where it comes from
Where the Warrior Diet comes from
Ori Hofmekler published The Warrior Diet in 2001. His argument was historical rather than clinical: that ancient warriors ate little during the day and one large meal at night, and that the pattern suits the body better than grazing. The book divides the day into about twenty hours of undereating and a four-hour window of overeating in the evening.
In the book the twenty hours are not a strict fast. Small amounts of raw fruit and vegetables and a little light protein are allowed in them, and the evening meal is where the real eating happens. The stricter reading most people now follow, often written 20:4, allows only drinks with no calories in the twenty hours. The window is the same four hours either way, and the planner draws it the same way; if you follow the book, read the long stretch on the clock as undereating rather than as a fast.
Neither version has been tested under its own name. What has been tested is a four-hour eating window, which is what the next section reports.
What the trials found
What the trials found about a four-hour window
There is one trial of a four-hour window and one of eating a whole day of food in a single meal. Both are small, and both are worth knowing.
No trial has tested the Warrior Diet by name. The nearest is an eight-week trial in 58 adults with obesity that put one group on a four-hour window from 3pm to 7pm. They ate about 550 kcal a day less without counting anything and lost about 3% of their weight — the same as a six-hour group. Cienfuegos S et al. Effects of 4- and 6-h Time-Restricted Feeding on Weight and Cardiometabolic Health: A Randomized Controlled Trial in Adults with Obesity. Cell Metabolism, 2020;32(3):366-378.
When healthy adults of normal weight ate a full day of calories in one meal for eight weeks, they lost fat mass but their blood pressure and total and LDL cholesterol went up, and they were hungrier. Stote KS et al. A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults. American Journal of Clinical Nutrition, 2007;85(4):981-988.
Read together: a four-hour window seems to make eating less easier, without counting, and does about what eating less does. It can also make it harder to eat enough protein, and one meal a day at full calories carried real costs in healthy adults. The Warrior Diet sits between the two.
What this page will not tell you
Three things this page will not claim
“The Warrior Diet is how our ancestors ate.”
It is the book's argument, not a finding. Nothing on this page depends on it, and the trials that exist tested the window, not the history.
“Four hours beats six or eight.”
The only trial that compared them found a four-hour and a six-hour window lost about the same. Shorter is harder, not better.
“The evening is the best time for the window.”
The book puts it there and the trial used 3pm to 7pm, but nobody has shown one four-hour slot beats another. The right window is the one your days can hold.
The other named protocols
Each has its own planner, built the same way.
- 5:2 Diet PlanTwo low days of 500 or 600 kcal, five normal days.
- Alternate-Day Fasting ScheduleA fast day every other day, planned two weeks at a time.
-
Warrior Diet PlanTwenty hours off, a four-hour window in the evening. You are here.
- OMAD CalculatorOne meal a day: what it must hold, and the week it sits in.
For the daily windows from 12:12 to 23:1, use the fasting schedule planner.