Choosing the right intermittent fasting window

Intermittent fasting windows differ in length and timing. Read on to learn about how to find the right fasting window.
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When practicing intermittent fasting, you have to decide on the timing and length of your intermittent fasting window. Beginners should start with a short fasting time, and extended fasting times are beneficial for weight loss. The timing of the fasting window mainly depends on personal preferences.

Written by
Sarah Neidler, PhD
Freelance Science and Medical Writer

When following intermittent fasting, you usually fast daily for a specific amount of time. Intermittent fasting is a very popular and effective weight-loss tool (1).

When you start with intermittent fasting, the first step is to find the right fasting window.

The right fasting window is very personal. One intermittent fasting window is not better than another. Most important is that the fasting window fits your lifestyle, goals, and personal preferences.

In this article, we talk about finding the right intermittent fasting window for you.

What is the best window for intermittent fasting?

When choosing your fasting window, you have to consider two aspects:

  1. Fasting length

  1. Timing of the fasting window.

1. Length: How long should you fast?

A yellow measuring tape.

You may have heard of different intermittent fasting methods. 16/8 intermittent fasting is the most popular, but there are many more. 14/10, 18/6, One Meal A Day (OMAD), Alternate Day Fasting (ADF),  and 5:2 fasting are other examples.

The intermittent fasting method determines the length of the fasting window. With 16/8 fasting, the fasting window is 16 hours per day, with 14/10, you fast for 14 hours, and with 18/6, you’re fasting for 18 hours. When practicing OMAD, you eat only one meal per day and fast for the rest of the day. 

With ADF and 5:2, you fast for entire days multiple times per week.

You can learn more about different intermittent fasting methods in a separate article.

So what method, i.e., what fasting length is right for you?

This depends on many factors, such as:

  • Your current eating schedule
  • (Intermittent) fasting experience
  • Health conditions, such as diabetes, heart disease, high blood pressure
  • Your weight and body composition (fat and muscle mass)
  • Age
  • Gender (man can fast for longer and more easily than women)
  • Physical activity

For most people, fasting experience and how much weight they have to lose are the most important factors.

Intermittent fasting experience

If you have no fasting experience at all, you should start your intermittent fasting journey with short fasting intervals. 12-hour overnight fasts, 14/10 and 16/8, are beginner-friendly intermittent fasting methods.

18/6 fasting and OMAD are quite advanced methods. You can try them when you’ve been practicing intermittent fasting for a while, and you feel like you could easily fast for longer. 

ADF and 5:2 are very advanced methods. With ADF, you eat every other day (ADF), and with 5:2, you fast for two entire (non-consecutive) days per week. You should only give them a try when you have a profound intermittent fasting experience. You should also consult your GP before you start with ADF or 5:2 fasting.

How much weight do you want to lose?

Person standing on a bathroom scale.

Many people start with intermittent fasting because they want to lose weight. Intermittent fasting is indeed a very powerful weight loss tool.

But you don’t have to lose weight with intermittent fasting. In fact, intermittent fasting provides many health benefits beyond weight loss (2). For this reason, many lean people practice these eating habits.

The more weight you have to lose, the longer you should fast. If you are lean and have only a couple of pounds to lose at maximum, it is recommended to opt for a method with short fasting intervals. 12-hour overnight fasting, 14/10 and 16/8, are ideal in that case. 

When you are overweight or obese, longer fasting intervals are more effective. More advanced methods such as ADF, 5:2, or even prolonged fasting are better options. But again, consult your GP before fasting for more than one day.

2. Timing of the intermittent fasting window: When should you fast?

Clock showing 240 pm.

Once you have figured out your best fasting length, you have to decide on the timing of your window.

For the shorter fasting intervals, it usually comes down to whether you skip breakfast or dinner. For instance, with the 16/8 method, most people eat two meals per day: either breakfast and lunch or lunch and dinner.

For most people, this decision is very easy. Many people are not hungry at all in the morning, and they force themselves to eat breakfast because they were told that it is the most important meal of the day. They should simply do what their body tells them–by listening to their hunger, they practice intermittent fasting. For example, they may eat from 12 pm to 8 pm.

Others are very hungry in the morning. For them, it’s much easier to skip dinner. They may prefer to eat from 7 am to 3 pm.

There are a few more things to consider:

  • Medications: When you have to take your medications with food, try to schedule your fasting window outside the times you have to take your medications
  • Social aspects: If family dinner is important to you, make sure that your fasting window doesn’t fall into dinner time.
  • Working hours: You likely have to adapt your fasting window to your work schedule.
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Can I change my eating window while intermittent fasting?

Is it important to always fast at the same time every day? No, not at all. It can make your life easier, but in the end, intermittent fasting is about giving your body well-deserved eating breaks.

If you work different shifts, it’s likely that you have to adapt your fasting times to your shifts.

Many people also follow a different schedule on weekends. During the week, they follow a schedule that fits their working hours. On the weekend, life is often less organized, and some people skip intermittent fasting. This is totally fine.

The most important thing is that your body gets used to fasting. When you’re still new to intermittent fasting, you should be as consistent as possible. Once you’re used to it, making exceptions and not fasting on weekends is not a problem.

In fact, a certain amount of flexibility makes intermittent fasting easier to sustain long-term. You should adapt your fasting schedule to your life, not the other way around.

Bottom line

Deciding on your fasting window is the first step when starting with intermittent fasting. Don’t overthink it, the most important aspect is that the window fits your lifestyle and personal preferences.

Once you have decided when to eat, you may ask yourself what to eat during your eating window. You can find more information on this topic in our “What to eat on an intermittent fasting plan” article.

Do you need help finding the right fasting window? Just join our intermittent fasting community for women only. There, you get all the support you need!


1. Welton S, Minty R, O'Driscoll T, et al. Intermittent fasting and weight loss: Systematic review. Can Fam Physician. Feb 2020;66(2):117-125.

2. Patterson RE, Laughlin GA, LaCroix AZ, et al. Intermittent Fasting and Human Metabolic Health. J Acad Nutr Diet. Aug 2015;115(8):1203-12. doi:10.1016/j.jand.2015.02.018

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