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This page is a short path through the basics. It explains what fasting is, the words people use, a few example schedules, what people often drink, and how a fast usually ends. It is for adults who want to learn. It is not a plan written for you.

If you want the same ideas in one printable piece, use the free guide: The PureFasting Beginner’s Guide.

What fasting is

Fasting, in the way this site uses the word, means a stretch of time when you do not eat. Intermittent fasting means that stretch repeats, usually most days or on days you choose, with a clear time when you do eat.

It is an eating pattern. The what is intermittent fasting guide says more about that. The Mayo Clinic describes intermittent fasting as a pattern of eating based on time limits. This site does not describe it as medical care or as a treatment.

Basic terms

Eating window. The hours when you eat your meals.
Fasting window. The hours when you do not eat.
16:8. A common example: about 16 hours fasting and an 8 hour eating window. The two numbers add up to 24.
Intermittent fasting. A repeating pattern of eating windows and fasting windows, not a single long fast.

You will also see 12:12, 14:10, and 18:6. The first number is usually the fasting hours. The second is the eating hours. People sometimes reverse that order in casual talk, so check which number is which before you copy an example.

How beginners can learn

A practical way to learn is to read one shorter schedule, notice your real day, and only then look at a longer window. Many people start by writing down when they already eat. That shows whether a 12 hour overnight gap is already close to their life.

Use the learning quiz if you want a guide suggested from your experience and how flexible your day is. The result is a page to read, not an instruction to start a fast.

The schedules guide compares examples side by side. The schedule planner draws one example day from a start time you choose.

Example schedules, not prescriptions

These are patterns people discuss. None of them is medically right for a person just because it is listed here.

12:12. Twelve hours eating, twelve hours fasting. Often this looks like finishing dinner and waiting until breakfast.
14:10. Fourteen hours fasting, ten hours eating. A modest step past a 12 hour overnight gap.
16:8. Sixteen hours fasting, eight hours eating. The example many articles use. Read 16:8 fasting.
18:6. Eighteen hours fasting, six hours eating. A shorter eating window. Read 18:6 fasting only after shorter windows feel familiar on the page and, if you try anything, in your own day.

A longer fasting window is not a higher grade. If a schedule makes the day feel rushed or harsh, a gentler window is the useful thing to study next.

What people commonly drink

During a fasting window, people commonly drink water, plain black coffee, or plain tea. Anything with calories, or with a sweetener, may end the fast for many people who are trying to keep a zero-calorie window. That is a convention used to define the fast, not a medical rule.

Milk, juice, soda, sweetened coffee, and alcohol are drinks for an eating window, if you use them at all. Details are in what to drink while fasting.

Ending a fast

A fast ends when you eat. For a daily eating window, that is an ordinary meal, not a special product. Sit down, eat a portion you would recognize as a normal meal, and stop if you feel unwell. The how to break a fast guide covers this without a ritual.

Common mistakes

Beginners often copy a long window on the first day, forget to drink water, or turn the clock into a test they must pass. Another mistake is changing medication timing or skipping meals that a clinician already built into a care plan. Read common fasting mistakes before you experiment.

Hunger is covered on its own page, because it is normal to feel it and also normal to stop: hunger while fasting.

Safety

Safety. People who are pregnant, breastfeeding, under 18, have an eating disorder or a history of one, have diabetes or hypoglycemia, take medication, or have a heart, kidney, or other medical condition should talk with a healthcare professional before fasting. Stop a fast and get help if you feel faint, confused, or unwell.

More questions are answered in the FAQ. Exercise is discussed separately in fasting and exercise, because a hard workout is not a required part of learning this topic.

Free beginner guide

If you want one document you can print or save, start there. It repeats the safety note and stays on the same educational footing as this page.

Get the free beginner guide