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Intermittent Fasting 20:4 vs. 16:8 – Which is Better?

Article

Fasting has been used in almost every religion and ancient culture for thousands of years. The benefits of fasting are numerous for those who approach it with the right mindset, but under the wrong circumstances; however, approaching it as if it's just another diet, then you are unlikely to reap the many benefits of fasting.

The evolution of fasting has brought forward multiple types of fasting, today we are going to focus on two popular methods of fasting; the 20:4 (also known as The Warrior Diet) and 16:8.

There are now so many different methods of fasting that it can be quite confusing to know which is the best type of fasting. So how do we know which method is best?

In my experience as someone who has practiced fasting consistently for over 10 years, and helped thousands to change their lives using intermittent fasting, the 16:8 and the 20:4 intermittent fasting methods are the simplest to incorporate.

There are differences, so let’s discuss which method is better.

THE 20:4 FASTING   

The 20:4 intermittent fasting is an evolved version of health and fitness author Ori Hofmekler’s Warrior Diet (Kubala 2018), or the one meal day. The Warrior Diet is based on the eating patterns of ancient warriors, who consumed little during the day and then feasted at night.

Here is how it is recommended to start with 20:4 intermittent fasting:

– The first step is to consume healthy food and drinks to keep your stomach full. It is done during the ‘pre-fasting window.’ Do not skip this step as it offers you energy to survive the next 20 hours healthily.

– The second step is to fast for 20 hours consecutively. You can consume water and zero-calorie drinks, but no food. It is an essential step as this is where your body goes into autophagy.

– Once your 20 hours of fasting are over, you can move on to the third step: eating! There is a 4-hour window where you can consume calories again.

You can consume as many calories as you like within that four-hour period, but it is advised to focus on nutrient-dense, whole foods.

 

Who Can Benefit from 20:4 Intermittent Fasting?     

As an expert in the field of intermittent fasting, I would say that the 20:4 fasting method is an advanced strategy.

It can be useful for people that have already tried other methods of Intermittent Fasting, have a good relationship with food, and who do not train more than 3 – 4 hours per week.

I personally like to combine the 20:4 fasting method with the 2 Meal Day. I usually incorporate the 20:4 fasting method on my rest days.

If your goal is weight loss, then it could be useful to incorporate the 20:4 fasting method for a short period of time and then return to less restrictive methods once you hit your goal weight.

Who is 20:4 Intermittent Fasting Not For?  

If you have never tried any methods of Intermittent Fasting, I would advise against the 20:4 fasting method.

To go from no fasting to 20 hours of fasting is a big jump, and you are likely to feel a lot of the negative short-term side effects of fasting, which can make it unnecessarily difficult.

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Women need to be especially careful with this method. As does anyone with a history of eating disorders, a bad relationship with food, and anyone who eats a lot of highly processed junk food.

Athletes should not use the 20:4 fasting method in training and competition season, but it could be a useful strategy to keep body composition where it needs to be during the offseason.

THE 16:8 FASTING     

The 16:8 fasting (Link 2021) is another evolved version of traditional fasting. It is considered relatively more straightforward than 20:4 for its longer eating window and shorter fasting window. Here’s how you can start the 16:8 fasting.

–   First Step: Decide what your eating window is going to be. Many people opt for finishing eating at 8pm and starting eating at 12pm. The hours you are asleep count as your fasting window.

–   Second Step: In the morning, you can drink water, zero-calorie drinks, black coffee, herbal teas, and black tea. Anything that contains any calories is not advised.

–   Third Step: After the 16-hour fasting window closes, you are free to consume food and drinks within the remaining 8-hour window. Again, it is advised to focus on nutrient-dense, whole foods to get the most out of this method of fasting.

Who Would Benefit from 16:8 Intermittent Fasting? 

As a health and fitness professional with 10 years experience helping people make intermittent fasting a way of life, I would say that the 16:8 intermittent fasting method can be used by many different people, safely and consistently.

It is an intermediate fasting strategy.

Anyone with a good relationship with food, who wants to lose some weight, improve their energy levels and who wants to reduce hunger levels, would benefit from 16:8 intermittent fasting.

16:8 Fasting is what I started with back in 2012 whilst I was traveling through South America, I then tweaked and optimised it to create the 2 Meal Day.

Who is 16:8 fasting not for? 

If you feel lightheaded when you skip a meal, if you experience “hunger”, and mostly eat processed food and takeaways, then it would be advised that you ease into the 16:8 fasting method using my ”30 Day Reset Plan”.

I would not advise heading straight into 16:8 fasting because you are likely to experience a lot of negative short-term side effects which could put you off fasting forever.

Women should be a bit more careful than men when using 16:8 intermittent fasting, and perhaps not incorporate it during ovulation.

Having said that, many of my female clients have done very well using 16:8 fasting.

BENEFITS OF BOTH 20:4 AND 16:8 FASTING                   

There are some key benefits that both kinds of fasting offer you. (Kamau 2022)

  • WEIGHT LOSS

Intermittent fasting restricts the time in which you can consume calories, therefore making it harder to overconsume. The side effect of this is it makes staying in a calorie deficit much easier (which is essential for fat loss). It can also improve metabolic flexibility, which means that your body can effortlessly transition between using carbohydrates for energy (from your food) to utilizing stored body fat as a form of energy.

  • LOWER INSULIN RESISTANCE

Insulin resistance is an epidemic and result of the modern western diet, where you eat regularly throughout the day, grazing on food all day long. When combined with eating highly processed junk food, your body can become resistant to the insulin that is released when your body is trying to lower your blood sugar levels. Intermittent fasting has been shown to stabilize blood sugar levels and improve insulin sensitivity.  I have personally had clients reverse their type 2 diabetes when eating in this way.

  • LOWER RISK OF EXCESSIVE INFLAMMATION

Inflammation is a way our bodies respond to infections and viruses in order to protect us. However, excessive inflammation can lead to severe diseases such as cancer, diabetes, and heart diseases. Luckily, intermittent fasting of any kind helps reduce the risk of chronic inflammation by reducing monocytes. Monocytes are cells that cause inflammation. Lower monocyte levels ensure a lower risk of inflammation.

  • IMPROVED ENERGY LEVELS (Because of Metabolic Flexibility)          

Fasting can improve metabolic flexibility, which means you can effortlessly shift between using different fuel sources. Once you are less dependent on the carbohydrates from food for energy, and you are able to shift into using stored body fat, many people report having more stable energy levels throughout the day.

             

CONCLUSION – WHICH ONE IS BETTER?

The methods of fasting are very similar, and even offer a lot of the same benefits, which one is better?

The answer very much depends on what your goals are, your relationship with food, and your experience with fasting.

If you are looking to experience more of the reported health benefits then the 20:4 might be a better option.

If your only focus is weight loss, then again, the 20:4 fasting method is likely to be a better option.

This comes with a caveat.

As a health and fitness coach, all I care about is sustainable results and consistency.

In my experience, most people will not be able to sustain the 20:4 fasting method in the long term, so I see it as less useful.

It can be a useful tool in the short term. But people are likely to return back to usual habits once they stop doing the 20:4.

However, I would say that the 16:8 fasting method can be incorporated in the long term.

And perhaps the optimal situation is to combine both methods, just like I do.

Again, if you want to lose weight, improve your relationship with food and get all the health benefits from Intermittent Fasting, I highly recommend starting my FREE Intermittent Fasting Short Course, where I show how to do it properly and get amazing results in a healthy and timely manner.

 

References

Davis, Charles Patrick. “How Long Do You Need to Fast for Autophagy?” MedicineNet (https://www.medicinenet.com/how_long_do_you_need_to_fast_for_autophagy/article.htm), 2021.

Kamau, C. “Intermittent Fasting 20/4: Will This Fasting Method Lead To Successful Weight Loss?”  (https://betterme.world/articles/intermittent-fasting-20-4/), 2022.

Kubala, Jillian. “The Warrior Diet: Review and Beginner’s Guide.” www.healthline.com (https://www.healthline.com/nutrition/warrior-diet-guide), 2018.

Link, Lizzie Streigt and Rachael. “What Is 16/8 Intermittent Fasting? A Beginner’s Guide.” www.healthline.com (https://www.healthline.com/nutrition/16-8-intermittent-fasting), 2021.