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Home arrow Nutrition arrow Intermittent Fasting arrow 20:4 Intermittent Fasting: How to Do It Safely and Successfully

20:4 Intermittent Fasting: How to Do It Safely and Successfully

Written by Thalia Oosthuizen
Fact checked by Rosmy Barrios, MD
Last update: October 17, 2023
5 min read 2160 Views 0 Comments
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Whether you’re looking to lose weight, improve your health, or boost your productivity, 20:4 intermittent fasting may be a viable option to consider.

20:4 intermittent fasting

Intermittent fasting methods come in all different shapes and sizes.

For some people, fasting is easier when the fasting period and eating window are closer together. And for others, intermittent fasting works best when the fasting period is much longer than the eating window.

Today, we’re going to take a look at the 20:4 intermittent fasting method and all the benefits of this particular way of eating.

What Is 20:4 Intermittent Fasting/Warrior Diet?

Like most intermittent fasting methods, 20:4 stands for the number of hours a day you’re fasting vs. the number of hours a day you’re eating. In this case, the eating window is 4 hours, while you fast for the remaining 20 hours.

This is a particularly extreme fasting period. For most people, it’s much easier or fits better into their lifestyle to fast for short periods of time, like 16 hours or 18 hours, while allowing for a 6 to 8-hour eating window. This is for people who are really serious about intermittent fasting.

This 20-hour fast is also known as the Warrior diet. It was created by Ori Hofmekler as an interpretation of how an ancient warrior might have fasted. 

The Warrior diet isn’t always a complete fast because someone should drink only water during the period. In fact, the original Warrior diet suggests eating small snacks during the day but limiting your food intake.

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Benefits of a 20-Hour Fast

While fasting for 20 hours out of the day may seem daunting, there are a lot of benefits that come with something like the Warrior diet. 

Let’s take a look at some of the benefits that a 20-hour fast can provide.

#1 Weight loss

As with most intermittent fasting methods, weight loss is one of the main benefits of the 20-hour fast. Some studies have shown that the Warrior diet can encourage a 14% increase in your metabolic rate, which encourages your body to burn more calories while you’re at rest, which helps with weight loss.

#2 Insulin sensitivity

Insulin resistance can cause a whole host of health problems, from increased risk of type 2 diabetes, heart disease, and even cognitive issues. 

The Warrior diet can help improve insulin sensitivity, which can lead to reduced risk of diabetes, heart disease, PCOS, and even improved water retention and clearer skin.

#3 Reduced inflammation

Inflammation can cause a number of risky diseases if you’re not careful. Some cancers, heart diseases, strokes, and respiratory diseases all come from chronic inflammation.

A 20-hour fast can reduce gut inflammation and encourage your body to recycle damaged cells that cause inflammation.

#4 Blood sugar control

Having high blood sugar is another way that people find themselves facing symptoms of type 2 diabetes.

All intermittent fasting helps reduce blood sugar, but with the 20-hour fast, your body really gets control of your blood sugar levels, which reduces the risk of developing type 2 diabetes.

#5 Cell health

We often tend not to think too hard about the cells in our bodies. But with a 20-hour fast, you can help encourage your body to enter into a state called autophagy.

Autophagy is the state in which our bodies break down damaged or dying cells and regenerate them into new, helpful cells.

20:4 Intermittent Fasting Weight Loss Results

Of course, we can talk about all the health benefits of the Warrior diet all we want, but there’s nothing quite like seeing the results with your own eyes.

Take a look at the results if you’re contemplating this 20-hour fast to help you lose weight.

Intermittent Fasting: 20:4 vs. 16:8

Which intermittent fasting protocol is best for you? Let’s take a quick look at the pros and cons of both the 20:4 and 16:8 methods of intermittent fasting.

20:4 Pros

  • Longer fast encourages your body to stay anabolic
  • Shorter eating window discourages overeating
  • Calorie restriction encourages weight loss
  • Potential health benefits
  • Encourages autophagy

20:4 Cons

  • Short eating window
  • Difficult to stick to
  • Hard to get proper calorie intake

16:8 Pros

  • Longer eating window allows for easier calorie intake
  • Easier to stick to for a long-term diet plan
  • Follows a more normal eating schedule
  • Promotes muscle gain

16:8 Cons

  • Slower rate of fat loss
  • Fewer fasting benefits
  • Doesn’t encourage autophagy

Whether you’ll benefit more from a 20-hour fast or a 16-hour fast depends entirely on your lifestyle, eating habits, and what you’re looking to get out of intermittent fasting. 

For some people, a moderate amount of weight loss is all they’re looking for. For other people, the complete overhaul that the 20-hour fast encourages is something to be desired.

No matter what form of intermittent fasting you’re looking for, make sure you’re building on a foundation of healthy habits.

Can’t Lose Weight With 20:4 Intermittent Fasting?

If you’ve changed your eating habits for some time now and still aren’t seeing the results you want, there may be a few reasons you’re not burning fat the way you should be.

Let’s take a look at some of the reasons you’re not losing weight.

#1 You’re eating too much

While having such a short eating period makes it harder to overeat, you might be eating too many calories. 

When it comes to losing weight, you essentially have to burn more calories than you take in.

If you’re not seeing any significant changes on the 20:4 diet, you might not be burning enough calories.

#2 You’re not eating nutritious foods

If you’re not eating too much, then you might not be eating the right foods.

Make sure you’re eating foods that help aid weight loss, like healthy fats, protein-rich foods, lean animal protein, raw vegetables, cooked vegetables, hard-boiled eggs, vegetable juices, and other nutrient-rich foods.

#3 Your fasting plan doesn’t work for you

Everyone works best on their own eating patterns. If you’re struggling with losing weight, you might need something more than a one-size-fits-all eating pattern.

#4 You’re not following your plan

A 4-hour eating window is just that: a 4-hour window! If you’re snacking too much during your 20-hour fast, you might find that you’re sneaking too many calories.

Consuming food in the middle of your fast can make it harder for your body to keep losing weight.

#5 You’re not consuming enough calories

Do you know how many calories you are eating during your eating period? Just like eating too much can make it hard to lose weight, so can not eating enough.

It may benefit you to start counting calories to make sure you’re getting enough and your body isn’t conserving fat rather than burning it.

A Word From Our RD

The 20:4 fasting or Warrior diet is a really intense form of fasting.

Your feeding window is really short, which means that many people may find themselves binge eating in order to feed themselves, or they may find themselves eating fewer calories than they need.

This type of eating method really isn’t good for people who are new to fasting. It takes a lot of understanding of food, fasting, and your own body. With such a short window, many people default to only eating one meal.

To better get your calories in, try meal prep for when it’s time to eat and keep some calorie-free drinks on hand to help you through the 20-hour fast. Meal prep can help ensure your eating window doesn’t turn into a 4-hour overeating period.

However, if you’re not careful, something as intense as a 20-hour fast can encourage eating disorders.

Many people are susceptible to developing disordered eating when trying to lose a bit of weight. Eating healthy is much more important than losing weight!

If you’re struggling with figuring out what the best way is, make sure you talk with your doctor. They’ll be able to help you out and decide which method works best for you.


The 20:4 fasting cycle is a very intense type of intermittent fasting where you will fast for 20 hours and eat for 4 hours. 

This type of fasting can encourage losing weight, reduce your inflammation, help your blood sugar, and even improve brain health.

There’s been enough scientific evidence that fasting encourages a whole array of health benefits – but this intense fasting can also have a few drawbacks.

These intense eating plans are hard to follow, and having such a short window in which to eat can make it hard to get the right amount of nutrients. However, there are many fasting apps, such as DoFasting, Zero, or Fastic app to help you follow the IF regimen.

You want to make sure that you talk with your doctor before making any intense lifestyle changes like this. Under proper medical supervision, the 20:4 intermittent fasting could be just right for you.

Written by Thalia Oosthuizen
Thalia has always wanted to be a writer, starting her first local newspaper at the age of 11. She also has enjoyed a passion for health and fitness since a young age, playing many sports through her schooling career, and still enjoys biking, running, and swimming today. She studied English Language at University for 3 years, developing a passion for spelling, grammar, and research. She now has over 10 years of experience writing, proofreading, and editing, and has paired this with her love for health and fitness by writing health content.
The article was fact checked by Rosmy Barrios, MD
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Written by Thalia Oosthuizen
Fact checked by Rosmy Barrios, MD
Last update: October 17, 2023
5 min read 2160 Views 0 Comments

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