Intermittent fasting: A primer - Leanbean ® | The unique supplement for women.

Part of our primer series. See also:

Intermittent fasting is an eating pattern where you alternate between eating and fasting.

The idea is to control when you eat rather than what you eat. As a result of fasting you’ll  eat fewer calories: an important part of a weight-loss lifestyle.

Intermittent fasting has grown in popularity over the last decade:

Number of people searching for intermittent fasting over time

There are many reasons for this popularity. Many people find intermittent fasting easier to stick to than a strict diet. It is linked to noticeable weight loss and several health benefits.

In this blog post we’ll explore some common questions about intermittent fasting, including:

This should give you the info you need to make an informed decision about whether intermittent fasting is right for you. We also recommend speaking with a doctor or qualified health professional before you start if you have questions or concerns.

Intermittent fasting methods

There are many ways to do intermittent fasting. The most common include:

  • The 5:2 Diet (AKA The Fast Diet)
  • Alternate Day Fasting (AKA 4:3)
  • The Warrior Diet (20:4)
  • 14:10
  • 16:8
  • 18:6

The numbers refer to either days or hours. In the 5:2 diet you eat five days of the week and fast for two; for the others with an x:y ratio you eat for x hours of the day and fast for y.

Let’s take a look at each.

The 5:2 Diet (aka The Fast Diet)

In intermittent fasting circles, 5:2 is a very popular choice. 

The diet is simple: you eat normally five days a week, then limit yourself to 500 calories for the remaining two days.

There’s no rule about which days of the week you should fast. There should be at least one day of non-fasting between fast days, though.

On the 5:2 diet you should aim for your normal recommended caloric intake on non-fast days. Don’t be tempted to chow down on lots of snacks and extra food to “make up for lost time”.

Alternate Day Fasting (aka 4:3)

If you alternate daily between fasting and not fasting, you’ll fast 3 days the first week and 4 days the following week:

  • Week 1, fasting days capitalised: m T w T f S s
  • Week 2, fasting days capitalised: M t W t F s S

This pattern follows the same logic as the 5:2 diet: eat normally on non-fast days, and limit yourself to 5-600 calories on fast days. 

Some studies have found significant links between the 4:3 diet and weight loss. 

The day-on, day-off structure of this intermittent fasting plan may be easier to remember, too. 

The Warrior Diet (20:4)

20:4 intermittent fasting was made popular by a man called Ori Hofmekler in the early 2000s. He wrote a book called The Warrior Diet that explored how ancient warriors ate.

Rather than taking 3 meals a day, warriors would eat very minimal portions during the day, then have the majority of their daily food in one big evening session.

For most 20:4 intermittent fasting adherents, this underfeeding and overfeeding pattern has now been whittled down to 20 hours fasting and 4 hours eating each day.

Ori’s book suggests eating low-carb foods like nuts and eggs during the hours that you’re underfeeding, and switching high-fat, high-protein foods later in the day. Modern interpretations don’t include these restrictions.


14:10 intermittent fasting is another popular method that has a longer daily window for eating: 10 hours, as opposed to Hofmekler’s 4.

Many people find this easier to work around, as a 4 hour window can quickly become quite prohibitive.

If you work a 9-5 for example, doing the 14:10 pattern would allow you to eat before work (at 8am, say) and again just after work (at 6). This is more forgiving than trying to cram all your daily calories into one small block of time.


In 16:8 intermittent fasting you fast for 16 hours of the day and eat for 8. The logic is otherwise the same: it’s just a case of finding the time ratio that works best for your routine and your body.


18:6 intermittent fasting is similar to the three intermittent fasting methods above, with an 18 hours on, 6 hours off ratio.

How long does it take to see results?

The answer here depends on a lot of factors, including how diligent you are with fasting, how many calories you eat on non-fast days, and your activity levels.

We looked at a scientific study that reviews other scientific studies about intermittent fasting. The idea of this study is to build a picture of the body of research.

The findings reviewed studies anywhere from 2 weeks to 52 weeks, and weight loss results were found at both ends of this spectrum.

This means that it may be possible to see results from intermittent fasting in as little as a fortnight, and that it may be possible to sustain this weight loss for a year or more.

We’ve written another blog post about how long it takes to see weight loss – why don’t you take a look?

The best intermittent fasting apps

Like the sound of intermittent fasting and need a hand keeping track of things? You’re in luck.

There’s an app for that

We scoured lists of the best intermittent fasting apps and found the three which feature most frequently:

1. Zero

This app has been featured on tons of world-leading websites and features input from leading doctors and researchers.

You’ll find a timer, a library of informative content, statistics on your journey so far, challenges to keep you motivated and tons more.

Average rating = 4.5 stars from 56k users

2. Femometer

This app sits alongside other female-centric apps in the developers’ range, and includes smart tracking tools to keep your fasting on track.

You can also access personalised plans based on your needs.

Average rating = 4.9 stars from 4.2k users

3. Bodyfast

This app features personalised plans and tracking tools for various different intermittent fasting methods. 

You can access info on your fasting stages, recipes from an expansive bank, food facts, and tons more.

Average rating = 4.7 stars from 71k users

The rest

Here’s the list of intermittent fasting apps which featured in other lists but didn’t make the top 3 based on average scores. Check them out if the ones above don’t meet your needs.

  • Simple, average score 3.5
  • Ate, average score 4
  • Window, average score 4.3
  • Fastient, average score 4.75
  • Life, average score 5.5
  • Fastic, average score 5.5
  • Vora, average score 7
  • Fasthabit, average score 7.7
  • Dofasting, average score 8
  • Sunrise, average score 9

What can you drink while intermittent fasting? 

There are no formal rules for intermittent fasting because of the various methods and personal preferences, so the information in this section is only a guide.

Can you drink water while intermittent fasting?

Yes, you can drink water on fast days. Water contains zero calories and it’s important to keep yourself hydrated.

Studies suggest that drinking water before meals is linked to reduced food intake, so having a glass of water before you eat on fast days may help you to feel full more quickly.

Can you drink coffee while intermittent fasting?

If you’re a caffeine addict, maybe you’ve got concerns about your ability to function without coffee on fast days.

The answer here depends on the type of coffee you like to drink. 

If you like a fruity frappe with a healthy swirl of whipped cream, you may want to give that a miss as it’ll take up most of your daily intake.

(The same applies for any coffee with milk…)

But if you like a strong, black espresso, you’re in luck. Those contain somewhere between 0 and 5.

Can you drink tea while intermittent fasting

There are a lot of types of tea. Those prepared by just pouring hot water onto dried leaves, fruits or other ingredients are fair game while fasting.

If you add milk or enjoy sweet variations like bubble tea, these will contribute to your daily calorie intake and may be better avoided.

Is intermittent fasting right for you?

In this blog post we’ve linked out to some authoritative info on intermittent fasting and answered common questions people have about methods, results, tracking and more.

Ultimately, it’s up to you to decide whether to fast or not. Some people are well suited to the lifestyle and feel satisfied with the results. Others will find different methods suit them better. Our advice from earlier applies: speak to a registered dietician or doctor before undertaking changes if you have any concerns.

We’d invite you to read our primers about the keto diet and the stages of weight loss, and to take a look at the benefits of Leanbean for weight loss. Figuring out what works best for you is one of the most important aspects of building a healthy weight loss lifestyle.

Disclaimer: The information on the Leanbean blog does not constitute medical advice and should not be used as such. If you would like to learn more about your dietary requirements and related aspects of your health, speak with a registered medical professional.


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