Intermittent Fasting 20/4: Your Complete Guide

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Are you considering going on a 20/4 intermittent fast?


Do you want to know the best way to perform this fast and maximise its results for your health?


Are you pondering whether to do the 5/2, 16/8 or 20/4 fast?


Great! As you’ve come to the right place!


Intermittent fasting has become one of the most popular dieting methods to lose weight. Unlike traditional diets, intermittent fasting focuses on eating and fasting windows that create repeatable caloric and nutrient deficit.


This article will share the 20-hour fast protocol so you can be informed on how best to start your fasting and reap the benefits of intermittent fasting.


So let’s get straight to it!

What is Intermittent Fasting 20/4?

The 2o/4 fasting protocol requires you to fast for 20 hours and then eat within a four-hour eating window.


You can eat your daily calorie intake in that 4-hour window and then repeat the 20-hour fasting period. You can perform this routine for as long as possible or until you reach your target goal.

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What is the history of the 20/4 fast?

Contrary to popular belief, the 20/4 fast is not known as the warrior diet. The 20/4 fast was adapted from the traditional 16:8 fast, whereby the eating and fasting windows were changed.

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Other types of intermittent fasting protocols

There are a few time-restricted eating (which is what intermittent fasting is) protocols that you can do that allows your body to get used to the concept of “window” fasting. These include


The 16/8 method: As the name suggests, your fasting window is 16 hours and your then eat your food in an 8-hour window. This intermittent fasting protocol is probably the more popular; and where people start.


The 5:2 diet: This IF protocol is also extremely popular and involves eating normally for five days, and then on two days, you eat no more than 500 calories. This causes a total caloric deficit in the seven days, and so weight loss occurs. The key to success for this protocol is to ensure the five days of “normal” eating is via a balanced diet.


Eat-Stop-Eat: This fasting protocol involves eating for a set period (say 12 hours), then stopping for another set period (say 24 to 26 hours), and then repeating.


The Warrior Diet: This involves eating small amounts of raw fruits and vegetables during the day and then having a larger meal at night.


Alternate-day fasting: As the name suggests, you usually eat for 24 hours, then for the next 24 hours, you do not eat any foods, just water.


Spontaneous meal skipping: Whilst not recommended, it can be structured to get your body used to fasting. This protocol allows you to skip breakfast or dinner and monitor how you feel.


Periodic fasting: Probably the most famous transitional protocol once you have mastered the shorted timed fasting options. You can fast for 3 to 5 days and then have 24 hours of eating.x


How to do the 20/4 intermittent fast?

Setting up your 20/4 intermittent fasting protocol requires following the points below.


  • Be prepared to fast for 20 hours and then eat your maintenance calories in a four-hour window. If you want to accelerate weight loss, then eat 300 to 500 calories below maintenance.


  • Many people succeed with the 20/4 fast by having their 4-hour window between 12 pm and 4 pm and then counting back the 20 hours until the next meal.


  • Eating during the day is highly recommended as it does not disrupt your circadian rhythm and ensures your body’s hormonal levels remain near normal. Ensure that your food intake and caloric intake match your goals.


  • Drink at least 2 litres of water daily and add fasting electrolyte salts if needed.


  • Try and abstain from tea\coffee, but if you feel the need for a caffeine hit, then only have some black coffee.


20/4 Intermittent fasting guide

Day 0


Purchase a 2 liter water bottle to ensure you take the recommended minimum water intake.


Work out how many calories you will be eating in your eating window. The usual caloric intake is between 1200 and 2000 calories but work this out based on your current stats.


Prepare a way to log all your results. A notepad will suffice


Take down your measurements. this can include your weight and also sizes (waist, chest, biceps etc.) and note down the dates


Feel free to write down how you feel, your thoughts and what you want to achieve from this diet


Mentally prepare yourself for the diet and visualise what you want to look like.


Decide how long you will be fasting. Will you cycle the fasts till you get to your target weight? If so, mentally prepare for that and create thoughts that lead to habits so that you can be successful.



Day 1 to Day 3


  • Make sure you are well hydrated and drink minimum 2 liters of water per day.


  • Plan to have two meals a day for the three days, Have a balanced diet across the two meals and aim to make them lunch and dinner.


  • Keep your carbohydrate consumption low, as this will prep your body for lower blood sugar levels and prime your entire body for the diet.


  • Perform moderate exercise, including a 45-minute brisk walk and some weight training.


  • Review your notes and goals and prepare your mindset with positive thoughts – you got this!


  • Have your last meal between 6 pm and 8 pm, and begin your first 20/4 fast.


Day 4 to day 8


  • This will be the start of your 20/4 fasting cycle. The aim here is to perform five days of 20/4 intermittent fasts.


  • You will have likely stopped eating at 8 pm the previous night, so you can next eat at 4 pm. During this day, keep yourself busy, drink your water, go for a walk and aim to go about your day as usual.


  • Feel free to meal prep for your eating window, and please ensure you follow a balanced diet rich in the essential foods we have discussed in this blog post. Aim to have protein and fats, and as little carbohydrates as possible. We don’t want to yo-yo the blood sugar, but we want to optimise ketosis.


  • Whilst your eating window will be 4 hours – you can shorten this if you hit your calories or meal requirements.


  • Break the fast with water and food and eat until you feel satiated. Remember that you have a 4-hour window, so pace yourself.


  • Once you have eaten your food, begin the next cycle of the 20-hour fast. You can go for a brisk walk as this will aid digestion.


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20/4 Intermittent Fasting Benefits

The benefits of intermittent fasting are immense and below are just a handful of the most commonly known ones:


Weight (fat) loss: The 20/4 fasting protocol will aid in weight loss if done consistently and followed as outlined above. The 20-hour fasting period will enable your body to break down free fatty acids and use them for energy.


Improved insulin sensitivity: Insulin resistance is a big issue in the western world due to the rise in processed foods and sugars. The 20/4 fast will reduce insulin resistance and assist in regulating blood sugar levels. This will enable your body to burn fat more efficiently and reduce your risk of developing type 2 diabetes.


Better mental clarity: Many people who follow IF report feeling focused with very little mental fog. This is especially true once the body moves from using glucose to ketones.


Reduced risk of heart disease: Intermittent Fasting can help to lower blood pressure whilst also improving cholesterol. Such effects can reduce the occurrence of heart disease.


Switches on autophagy: A significant benefit to intermittent fasting is the body’s ability to switch on something called autophagy. This is the act of the body preserving itself and cleaning up dead and unwanted cells.


Increase immune function: Research has suggested that fasting significantly impacts the body’s immune system, making it stronger.


Reduce chronic inflammation: The fasting protocol has been shown to reduce CRP levels in the blood and positively impact the body. As inflammation is seen to be a potential root cause for several chronic illnesses, keeping it low in the body is a good idea.


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20/4 Fast Challenges

No doubt comes without its challenges, and intermittent fasting is no exception. Whilst many of them can be managed or mitigated. It is worth knowing that they can creep up on you if you are not aware:


Extreme hunger and cravings: Be prepared to be mentally strong when you start the fast. Your blood sugar levels will drop to a lower (safe) level so that cravings may appear. These will go away once your body gets used to the fasting window.


Socializing: Fasting for 20 hours per day can be challenging if you have social engagements requirement eating! Many people find this problematic as turning to a social engagement and only drinking water can be seen as challenging.


Nutrient deficiency: It is essential that when you do eat in the 4-hour window, you consume a balanced diet (and eat healthily) so that you can supply the body with all the nutrients it needs.


Dehydration: If you don’t consume at least 2 liters of water per day, there is a risk of dehydration that needs to be avoided. Hence, many people purchase a 2L water bottle and ensure they drink it each day.


Lower energy levels: Nearly everyone who starts an intermittent fast will experience an energy level crash. This is expected in the initial periods as the body adapts to the change. After the first few fasts, the energy level issue goes away, and the body recognizes what it needs to do to compensate for the change.


Sleep Issues: Many people avoid sleep issues if they ensure their eating window is in the early afternoon. Doing so allows the body to digest the food and ensures the gastrointestinal tract performs as needed.


Medication consumption: If you have to take medication that requires food with it, then you may have to see if that can be taken during your 4-hour feeding window.


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What to eat on a 20/4 Intermittent Fast?

Now that you know what intermittent fasting is and what it involves, we can now look at what you need to eat to ensure the 20/4 fast is optimised for health benefits and weight loss!


We must fuel the body with the correct nutrients via a balanced diet when on an intermittent fast. So the eating window is your chance to fuel your cells with the right macro and micronutrients and prepare them for the next fasting period.


For the ideal balanced diet, you should look at the following food groups


Fatty and organ meats




Full-Fat Cheeses


Full-Fat Yogurts


Bone broth


Cruciferous vegetables


Lots of water


Remember that before the four-hour eating window, the body uses ketones (stored fat) as its fuel source. So it would be best to feed the body a mix of protein and fats with minimal carbohydrates.


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Tips for Intermittent fasting 20/4

Intermittent fasting can be challenging for many in the initial stages, as time-restricted eating windows require patience and willpower.


Here are our tips to make your fasting experience easier:


Planning: The ongoing success of your 20/40 fast will be largely determined by your willpower and planning. Make sure you set yourself up for success with this diet. Prepare your food and eating windows, work on your mindset and will power and focus on small steps to hit your overall health and weight loss. You got this!


Mindset: Your mind will take your body where you tell it to! The 20/4 fast requires willpower and patience to succeed. But once you witness the results, you will be motivated to continue your cycle of fasts. Manage and observe your thoughts and ensure you keep them positive.


Diet: Your eating windows should be filled with nutritious whole foods such as high-quality proteins, cruciferous vegetables, eggs and healthy fats like avocados and nuts.


Hydration: Ensure you drink at least 2 liters of water daily and add an electrolyte mix if needed.


Exercise and Cardio: Limit activity to light cardio or walking during the fasting windows. A 60-minute brisk walk will increase the fat breakdown in your body and boost ketones.


It’s ok to Start Slowly: There are a few variations to the timed fasting protocol, and you can start with 16/8, 18/6 and then 20/4 fasts. This allows your body to get used to the fasting windows.


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Is 20 4 intermittent fasting good?

The 20/4 intermittent fasting protocol is an advanced form of the diet, so it does need extra care and attention when followed. Ensuring your water intake is high, your electrolytes are good, and you eat a balanced diet in the eating window will ensure that you address any issues that can arise.

What does 20 4 intermittent fasting mean?

20/4 intermittent fasting means that you fast for a 20-hour window and only drink water, and once this window is completed, you consume your food in a 4-hour eating window.

Is 20 4 better than 16 8 for fasting?

Due to autophagy and blood glucose lowering, a more extended fasting period will always be better if you want more comprehensive health benefits.

Is it OK to fast for 20 hours every day?

If you have checked with your physician and have performed a few fasts without issue, then yes, fasting every day for 20 hours is ok. The overall health benefits of lower blood sugar, lower inflammation and optimised blood pressure can only be positive for your health.

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Is 20 4 the same as OMAD?

No. One Meal A Day means you eat ONE meal in a sitting which is usually done within a 30- to 60 min period. The 20/4 protocol allows you to eat in a four-hour window.

How Much Weight Can You Lose On A 20/4 Intermittent Fasting?

If you were to perform 20/4 fasting for seven days, then it is likely that you will lose up to 5 lbs of weight. The fewer calories, more extended fasting and restricted eating window will aid overall weight loss.

Will the changing eating patterns of intermittent fasting cause any health issues?

No. Timed interval fasting will not cause adverse health effects as long as you aim to have your eating window during the day.

Will 20/4 allow me to have better blood sugar control?

Yes. The extended fasting window will normalise raised blood sugar levels. If you also follow a very low-carb eating window, this will assist in reducing insulin resistance.

Conclusion: Should you start the 20/4 fasting protocol?

Yes, you should start the 20/4 protocol, but only if


  • Your physician has given you the all clear


  • You are not under any contradictory medicine


  • You have tried the 16:8 protocol to get accustomed to the diet.


  • You fully understand the impact of the diet and follow it cautiously.


Considering the above guidance, the 20/4 diet can be a fantastic diet protocol for better health and lower body fat.


(oh, and do keep in touch and check in with us regularly for more fantastic content. For a complete list of our previous blog posts, please go here)


Recommended Read: >>> Intermittent Fasting 18/6 <<<

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