Fasted FASTED

Alternate-Day Fasting Schedule

An alternate-day fasting schedule is a fast day, then an eating day, repeated without a break: seven fast days in every fourteen. On a fast day you eat about 500 kcal in one meal — the figure Krista Varady published in 2013 — or nothing at all on the strict version. Pick your first fast day and your eating hours below; the planner lays out two weeks, prints them and puts every fast day in your calendar.

Alternate-day fasting is the one common protocol where the weekday tells you nothing. A week has seven days, so the fast days move: Monday, Wednesday, Friday and Sunday one week, Tuesday, Thursday and Saturday the next. This planner dates every day from the one you start on and draws the whole fortnight on one clock, so today is never a question.

Check with a clinician first. Do not start alternate-day fasting 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 first: a fast day every other day is exactly the pattern that makes a fixed dose unpredictable. Stop and eat if you feel faint, shaky or confused.

Your week

Plan your alternate-day fortnight

Which version
Mon 5 Tue 6 Wed 7 Thu 8 Fri 9 Sat 10 Sun 11 Mon 12 Tue 13 Wed 14 Thu 15 Fri 16 Sat 17 Sun 18

Tap or hover a day to read it.

Week of 5 Oct

  1. Mon5 Oct Fast dayAbout 500 kcal, in one meal at 13:00
  2. Tue6 Oct Eating dayEat 08:00 to 20:00
  3. Wed7 Oct Fast dayAbout 500 kcal, in one meal at 13:00
  4. Thu8 Oct Eating dayEat 08:00 to 20:00
  5. Fri9 Oct Fast dayAbout 500 kcal, in one meal at 13:00
  6. Sat10 Oct Eating dayEat 08:00 to 20:00
  7. Sun11 Oct Fast dayAbout 500 kcal, in one meal at 13:00

Week of 12 Oct

  1. Mon12 Oct Eating dayEat 08:00 to 20:00
  2. Tue13 Oct Fast dayAbout 500 kcal, in one meal at 13:00
  3. Wed14 Oct Eating dayEat 08:00 to 20:00
  4. Thu15 Oct Fast dayAbout 500 kcal, in one meal at 13:00
  5. Fri16 Oct Eating dayEat 08:00 to 20:00
  6. Sat17 Oct Fast dayAbout 500 kcal, in one meal at 13:00
  7. Sun18 Oct Eating dayEat 08:00 to 20:00
Fast days
7 of 14
Fast-day food
500 kcal
Eating days
08:00–20:00
Longest gap
19h

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.

Add to calendar (.ics) Print the week Quiet calendar version

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 alternate-day fasting comes from

Fasting every other day came to people from animal research, where it had extended life in rats and mice for decades. The first human study, published in 2005 by Leonie Heilbronn and colleagues at the Pennington Biomedical Research Center, had 16 adults eat nothing every other day for three weeks. They lost a little weight and stayed hungry on fast days throughout, and the authors suggested adding one small meal.

That meal is the version most people now follow. Krista Varady at the University of Illinois Chicago ran a series of trials in which the fast day carried a quarter of each person's energy needs, and in 2013 she set out the plan for general readers in The Every-Other-Day Diet, rounding the fast-day meal to about 500 kcal. The strict, no-food version survives too: a trial in Graz tested it for four weeks in 2019.

Measured from the last meal to the next, a strict fast day is longer than a day. If your eating days close at 8pm and open at 8am, the fast runs from 8pm the evening before to 8am the morning after — thirty-six hours, which is why the strict version is often called 36-hour alternate-day fasting.

What the trials found

What the trials found about alternate-day fasting

It is one of the most studied fasting patterns, and the longest trial is the most sobering.

The longest trial of alternate-day fasting ran for a year in 100 adults with obesity, with fast days at 25% of energy needs. It lost no more weight than eating 75% of needs every day — 6.0% against 5.3% at twelve months — and 38% of the fasting group dropped out, against 29% on the daily cut. People ate more than planned on fast days and less on the days between. Trepanowski JF et al. Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance, and Cardioprotection Among Metabolically Healthy Obese Adults: A Randomized Clinical Trial. JAMA Internal Medicine, 2017;177(7):930-938.

A twelve-week trial in 32 adults of normal weight or overweight found the alternate-day group lost 5.2 kg more than the controls, with no change in lean mass. Varady KA et al. Alternate day fasting for weight loss in normal weight and overweight subjects: a randomized controlled trial. Nutrition Journal, 2013;12:146.

In the first human study of the pattern, 16 adults who fasted every other day for 22 days were still hungry on fast days at the end of it; the hunger never settled. The authors suggested adding one small meal on fast days — which is what the modified version does. Heilbronn LK et al. Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism. American Journal of Clinical Nutrition, 2005;81(1):69-73.

A four-week trial in Graz tested the strict version, with no food at all on fast days, in healthy adults without obesity. They ended up eating 37% fewer calories on average. Stekovic S et al. Alternate Day Fasting Improves Physiological and Molecular Markers of Aging in Healthy, Non-obese Humans. Cell Metabolism, 2019;30(3):462-476.

Read together: alternate-day fasting is a way of eating less that suits some people, and it does about what eating less does. The year-long trial is the one to weigh most, and its most useful number may be the dropout rate — which is an argument for starting on the modified version and choosing eating hours you can keep.

What this page will not tell you

Three things this page will not claim

“Alternate-day fasting beats cutting calories every day.”

The year-long trial found the same weight loss either way, and more people quit the fasting. Shorter trials that found a benefit mostly compared fasting with doing nothing.

“Fast days get easy after the first week.”

In the first human study hunger on fast days never settled over three weeks. Some people adapt; the evidence does not promise that you will.

“The strict version works better than the modified one.”

Nobody has tested the two against each other. The strict version is harder, and the modified version was invented because the strict one was hard.

The other named protocols

Each has its own planner, built the same way.

For the daily windows from 12:12 to 23:1, use the fasting schedule planner.

How the fortnight is worked out

The start date you pick is the first fast day, and every day after it alternates: fast, eat, fast, eat. The planner shows two weeks, not one, because seven is odd and the fast days change weekday every week; the fortnight is the shortest span in which the pattern comes back to where it began. Every row carries its date for the same reason.

There are two versions and the page draws either. The modified version eats about 500 kcal in one meal on a fast day — Krista Varady's figure in The Every-Other-Day Diet (2013), rounding the 25% of energy needs her trials used. The strict version eats nothing on fast days, the form a four-week trial in Graz tested in 2019. On eating days you set the hours; the default is 8am to 8pm, and it is a default, not a recommendation.

The longest gap under the clock is arithmetic on your own hours. On the strict version it runs from the close of one eating day, through the whole fast day, to the opening of the next: with an 8pm close and an 8am opening that is four hours, then twenty-four, then eight — thirty-six. On the modified version the fast-day meal splits it in two and the longer half is printed.

The calendar file publishes an all-day event on each fast day and your eating hours on each day between, for four weeks from your start date or today, whichever is later. The alternation stays anchored to your start date, so a subscription made late still lands its fast days on the right dates.

Where this comes from

  1. 1. The Every-Other-Day Diet (Varady K), catalogue record — Hachette Books, 2013 — Open Library
  2. 2. Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance, and Cardioprotection Among Metabolically Healthy Obese Adults: A Randomized Clinical Trial — Trepanowski et al., JAMA Internal Medicine, 2017 (PubMed)
  3. 3. Alternate day fasting for weight loss in normal weight and overweight subjects: a randomized controlled trial — Varady et al., Nutrition Journal, 2013 (PubMed)
  4. 4. Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism — Heilbronn et al., American Journal of Clinical Nutrition, 2005 (PubMed)
  5. 5. Alternate Day Fasting Improves Physiological and Molecular Markers of Aging in Healthy, Non-obese Humans — Stekovic et al., Cell Metabolism, 2019 (PubMed)
  6. 6. RFC 5545 — Internet Calendaring and Scheduling Core Object Specification (iCalendar) — Desruisseaux (ed.), IETF, 2009

Nothing on this site is medically reviewed — it cites its sources so you can check them. Read our editorial policy. Method last checked 28 September 2026.

Alternate-day fasting is the one common protocol where knowing today's weekday does not tell you what today is. Monday was a fast day last week and an eating day this week, and by the third week most people are counting on their fingers.

That is the whole reason this planner dates every row and puts the fortnight on one clock: the pattern is anchored to the day you started, not to the names of the days.

Frequently Asked Questions

What does an alternate-day fasting schedule look like?
A fast day, then an eating day, then a fast day, without a break: fourteen days hold seven of each. Because a week has seven days the fast days change weekday every week — Monday, Wednesday, Friday and Sunday one week, then Tuesday, Thursday and Saturday the next — which is why this planner lays out two weeks rather than one and dates every row. On the eating days you eat normally inside the hours you set; on the fast days you eat about 500 kcal in one meal, or nothing at all on the strict version.

How many calories can I eat on an alternate-day fast day?
The trials that built the evidence used a quarter of each person's energy needs, and Krista Varady, who ran many of them, rounds that to about 500 kcal in her 2013 book The Every-Other-Day Diet. The strict version eats nothing on fast days; a four-week trial in Graz in 2019 tested that one. The first human study, in 2005, found hunger on fast days never settled when there was no food at all, and its authors suggested adding one small meal — which is where the modified version came from.

What is 36-hour alternate-day fasting?
The strict version measured from the last meal to the next one. If your eating days close at 8pm and open at 8am, a no-food fast day runs from 8pm the evening before, through the whole day, to 8am the morning after: four hours, then twenty-four, then eight, which is thirty-six. The planner does that arithmetic from your own hours and prints the longest gap under the clock.

Does alternate-day fasting work better than cutting calories every day?
The longest trial says no. A year-long trial in 100 adults with obesity found alternate-day fasting lost about the same as eating 75% of needs every day — 6.0% of body weight against 5.3% at twelve months — and 38% of the fasting group dropped out against 29% on the daily cut. People ate more than planned on fast days and less than planned on the days between. It is a way to eat less that suits some people, not a method that does more than eating less.

Can I exercise on a fast day?
Light exercise, yes; most people do. Hard training on a no-food day is a different matter, and on the modified version it helps to put the fast-day meal after the session rather than before. If a fast day leaves you dizzy or shaky, stop, eat, and move the hard sessions to eating days.

Can I put my fast days in my calendar?
Yes. The calendar file puts an all-day event on each fast day and your eating hours on each day between, for four weeks from your start date, and keeps the alternation anchored to that date so the fast days stay on the right dates however late you subscribe. Use the quiet version if other people can see your calendar: it calls fast days light days and shows eating days as hours only.

Who should not do alternate-day fasting?
Anyone pregnant or breastfeeding, anyone under 18, and anyone with a current or past eating disorder should not start it. Anyone with diabetes, or taking insulin or another medicine that lowers blood sugar, should not start it without their clinician changing the plan first: a fast day every other day is exactly the pattern that makes a fixed dose unpredictable. Stop and eat if you feel faint, shaky or confused.

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Time a single long fast on Fasted

Fasted does not run alternate-day fasting as a pattern: its catalogue is six daily windows from 12:12 to 23:1 and four longer fasts from 24 to 72 hours. Its 36-hour fast times one strict fast day from start to finish; the calendar file on this page keeps the alternation.

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