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Nutrition » Diets » Intermittent Fasting 20/4: Will This Fasting Method Lead To Successful Weight Loss?

Intermittent Fasting 20/4: Will This Fasting Method Lead To Successful Weight Loss?

intermittent fasting 20/4

What is 20/4 Intermittent Fasting?

Intermittent fasting is an eating pattern that has been widely accepted by many people trying to lose weight. Of all the different methods to do it, intermittent fasting 20/4 is one of the stricter versions. What are some intermittent fasting 20/4 benefits? Is intermittent fasting 20/4 everyday healthy and sustainable long-term? Read on to find out this and more.

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The intermittent fasting 20/4 method is also known as “The Warrior Diet.” This diet was created in 2001 by Ori Hofmekler, an Israeli Special Forces member turned health and fitness author. It is important to note that the warrior diet is not based on science but rather a deduction of Ori’s experiences while he worked in the military (22).

Also, some supporters of this eating pattern claim that humans are natural nocturnal eaters and that eating at night allows the body to gain nutrients in line with its circadian rhythms (16).

What are Other Types of Intermittent Fasting?

As stated above, intermittent fasting 20/4 is just one of the eating patterns under the umbrella of intermittent fasting. Other methods include (16):

  • The 12-hour fast

This gives you a 12-hour eating window.

  • The 16-hour fast

This is the most popular type of intermittent fasting, especially among beginners. The 16/8 method gives you an 8-hour eating window.

  • The 5:2 method

Another popular variation is the 5:2 diet. It does not rely on hours to define the eating windows. On this variation, participants eat normally for 5 days a week and drastically cut down their caloric intake on the remaining 2 days. On the 2 fasting days, men and women generally consume 600 and 500 calories, respectively. For health reasons, these two days are not practiced back to back, i.e., you can fast on Tuesday and Thursday but not on Tuesday and Wednesday.

intermittent fasting 20/4 everyday
  • The alternate-day fast

This is a bit like the 5:2 diet, but it involves fasting every other day instead of just two days a week. There are no specific rules for this as some people live on a liquid diet on the fasting day while others allow up to 500 calories on these days.

  • The 24-hour fast

It is also known as the “Eat-Stop-Eat Diet.” In this variation, people go for 24 hours without eating anything. It can be done either once or twice a week, and followers of this method drink unsweetened coffee or tea, water, and other calorie-free drinks.

  • Meal skipping

The name translates to the method. You are not regulated by any hours or caloric intake. With this variation, you just opt for which meal to skip per day.

  • The OMAD diet

Also known as the “One Meal A Day Diet,” is referred to as a more strict version of intermittent fasting 20/4. People do OMAD fast for 23 hours a day, which gives them a 1-hour eating window. OMAD does not require you to count calories neither are there any food off-limits on this eating plan. However, healthy and nutrient-rich foods are encouraged for weight loss and health reasons (18).

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intermittent fasting 16/8 vs 20/4

How to Properly do Intermittent Fasting 20/4?

When people choose intermittent fasting 20/4, many assume that it just involves cutting down your feeding window to only four hours a day. While this is essentially what a 20-hour fast means, many people are unaware that Ori Hofmekler, the diet’s developer, created an initial 3-week, 3-phase plan.

According to Ori, this plan and its phases are necessary as they give your body a chance to get used to the Warrior Diet, improving its ability to utilize fat for energy. The plan is as follows (23):

Week one – Phase one

This is also known as the detox period. During this phase, Ori states that you should:

1. Undereat during the 20-hour fast window – Undereating means that you can have small amounts of foods like hard-boiled eggs, raw vegetables and fruits, yogurt, and cottage cheese. In terms of drinks, you can have broth, milk, or vegetable juices, albeit in small amounts. You may drink water, coffee, and tea.

2. The Overeating window – During these 4 hours, Hofmekler suggests that you break your fast by consuming a salad with oil and vinegar dressing. After this, you can have one large meal or multiple smaller meals that you can fit within these few hours. Your meals should be made up of whole grains, plant-based proteins like beans, and more vegetables.

intermittent fasting 16/8 vs 20/4

Week Two – Phase Two

This is known as the high-fat week. The rules for this phase are as follows:

1. The Undereating window – During these 20 hours, you should consume the same small amounts of foods, vegetable juices, milk, and clear broth like you did in the first week.

2. The Overeating window – During these 4 hours, you are not allowed to consume whole grains, other starchy food, or carbohydrates like you did in the first week. Instead, you will break your fast by consuming a salad with an oil and vinegar dressing, then your next meal (or smaller meals) should consist of cooked vegetables, nuts, and animal protein.

Week Three – Phase Three

This is known as the “concluding fat loss week” or the “high-carb high-protein cycle.” During this week, your food consumption should be as follows (22):

  • 1 to 2 days high in carbs
  • 1 to 2 days high in protein and low in carbs
  • one to two days high in carbs
  • 1 to 2 days high in protein and low in carbs

High-Carb Days

1. Undereating window – Eat the same foods that you had been eating during the first week.

2. Overeating window – Break your fast with the same salad that you have been having. The next large meal or smaller meals should consist of cooked vegetables, some animal protein, and one main source of carbohydrates like corn, rice, potatoes, whole-wheat pasta, barley, or oats.

intermittent fasting 20/4

High-Protein – Low-Carb Days

1. 20-hour Underfeeding window – The same foods and drinks that you have been having throughout the previous weeks.

2. 4-hour Overfeeding window – Break your fast with the same salad, and the next meals should have 227 to 454 grams (total) animal protein and some cooked, non-starchy vegetables.

3. Fruit – While you should not consume grains or starchy veggies during these days, you can have some fruit if you are still hungry at the end of the night.

Once you have completed this 3-week phase, you are supposed to start it all over again. If this suggestion does not appeal to you, just stick to the undereating rules set for the 20 hours and then consume healthy, high-protein meals in the 4-hour overfeeding window.

What Should I Eat with 20/4 Intermittent Fasting?

Now that you know how to effectively follow the intermittent fasting 20:4 rules, your next step is to make a meal plan. Meal planning is an easy way to ensure that you always have meals at the ready for whenever you break your fast. This ensures that you always have healthy meals or snacks, which prevents you from consuming unhealthy food options.


Since intermittent fasting is an eating plan and not a diet, people do not have any strict regulations on what kinds of foods or drinks they should eat during the feeding window. However, the warrior diet stands out as it offers some guidelines on how to eat. Your meals should make up a balanced diet, which is a diet that gives your body enough nutrients to work effectively, protecting itself against disease, infection, fatigue, and low performance (2).

With that in mind, here are some foods that should be included in your 20/4 intermittent fasting meal plan or grocery list. Not only will these foods help with your weight loss goals, but they are also good for your overall health.

  • Complex carbohydrates

Complex carbs are foods such as whole wheat, brown and wild rice, oats, and quinoa, among others. Not only do they have more nutrients than simple carbohydrates, but they are also great for your digestive and heart health (17).

When fasting for 20 hours, you will end up feeling quite hungry, and sometimes the suggested foods for the undereating window are just not enough to curb the hunger. Foods high in fiber keep you fuller for longer and may help you not feel hungry early in the day, making your fast easier (5).

intermittent fasting 20/4 everyday
  • Dark leafy greens

Include leafy greens in the salad to break your fast. Not only are they low in calories, carbs, sodium, and cholesterol, but they also have high levels of fiber, iron, magnesium, potassium, and calcium (4). Popular examples of dark leafy greens include bok choy, arugula, Swiss chard, kale, collard greens, and Romaine lettuce (21).

  • Fruits

As mentioned above, fruits can be consumed as dessert during week 3 – phase 3, or throughout the diet during the underfeeding window. Fruits are an excellent source of essential vitamins and minerals. Not only are they high in fiber, but they also provide a wide range of health-boosting antioxidants (24).

Some healthy fruits that should be included in your 20/4 intermittent fasting meal plan include apples, lemons, kiwis, strawberries, bananas, grapefruits, black and blueberries, passion fruits, watermelon, and pineapples, among others.

intermittent fasting 20/4
  • Lentils and legumes

They are naturally low in fat, practically free of saturated fat, and provide protein, complex carbohydrate, B vitamins, iron, copper, magnesium, manganese, zinc, and phosphorus (12). They are also high in fiber, which means that they are quite filling and will keep you from feeling hungry too early in the day.

  • Oily fish

Examples include trout, tuna, salmon, mackerel, herring, sardines, and pilchards. They are rich in protein and omega-3 polyunsaturated fatty acids, which help reduce inflammation and may help lower the risk of heart disease, cancer, and arthritis (8).

  • Lean proteins

A high protein diet is part of the phase three-cycle. In your diet, proteins help with weight loss by increasing the satiety hormones while reducing levels of the hunger hormone, ghrelin. Proteins also boost your metabolism, making you burn calories faster (9).

Lean proteins are better since they have less saturated fat. Types of lean meat include examples such as lean cuts of beef, lamb, veal, pork, chicken, turkey, duck, and seafood like crab, lobster, mussels, oysters, scallops, and clams. Eggs are also a fantastic source of lean protein.

  • All kinds of vegetables

A diet rich in vegetables and fruits can help lower blood pressure, reduce the risk of heart disease and stroke, prevent some types of cancer, lower the risk of eye and digestive problems, and positively affect blood sugar levels, which can help keep appetite in check (25).

There are starchy and non-starchy vegetables:

  1. Non-starchy veggies include cucumbers, eggplants, amaranth, Brussels sprouts, cabbage, cauliflower, celery, mushrooms, okra, peppers, squash, asparagus, bean sprouts, and more (13).
  2. On the other hand, starchy vegetables include yams, white potatoes, plantain, sweet potatoes, beans, corn, pumpkins, winter squash, and more (19).

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What are Some Intermittent Fasting 20/4 Benefits?

If you are wondering, “how does 20/4 intermittent fasting affect the body?” Here are some benefits that may be experienced while following the warrior diet include:

weight loss

1. Weight loss

A controlled trial published in 2009 showed that people who followed an eating pattern that closely resembled the 20/4 intermittent fasting method lost more weight than those who ate the same amount of calories but consumed them in several meals throughout the day (1). It is believed that you lose weight through fasting because it is harder for you to eat as many calories during a small feeding window.

2. May help protect against Alzheimer’s

Note that these results are from research done on animals (mice) and not humans. In 2017, a study posted online revealed that intermittent fasting, in general, may help protect against Alzheimer’s disease through the restoration of Aquaporin-4 Polarity (11). Later in 2018, another study suggested that intermittent fasting protects against this disease through the increase of lipoproteins to the brain (10).

3. May improve blood sugar levels

Intermittent fasting is generally associated with improving blood sugar control and insulin sensitivity (20). A pilot study done in 2017 showed that fasting for 18 to 20 hours a day could lead to weight loss and post-meal blood sugar control (6). This shows that fasting could be extremely beneficial to patients with type 2 diabetes. However, if you are suffering from this disease, please talk to your doctor before trying the 20-hour fast, or any other form of intermittent fasting.

4. May help with inflammation

Some types of intermittent fasting have been associated with a decrease in chronic inflammation (15). While this research did not involve the intermittent fasting 20/4 method, you may still reap the same benefits. Excess inflammation can lead to illnesses such as heart disease, diabetes, some cancers, bowel disorders, and more.

20/4 intermittent fasting meal plan

Are there any Side Effects of Intermittent Fasting 20/4?

Yes, there are. Some downsides of participating in a fasting eating plan include:

  • May lead to a binge-eating disorder – This is a serious eating disorder in which you frequently consume unusually large amounts of food and feel unable to stop eating. Fasting has been linked to the increase in the onset of binge-eating (7).
  • May lead to nutrient deficiencies – Since you are eating during a very small window, you are unlikely to consume the recommended servings of fruits and vegetables per day. Nutrient deficiencies that can lead to anemia, fatigue, weakness, poor eye health and immunity, short term memory loss, diarrhea, dementia, and skin disorders, muscle loss, osteoporosis, and depression (14).
  • It has no basis in science – As we mentioned above, this diet was developed by an ex-military guy who based all his findings from his experience during active duty. He is neither a scientist, nutritionist, nor a dietitian. On the other hand, most of the benefits mentioned have been linked to fasting in general or other forms of intermittent fasting and not the 20/4 method.


How Many Calories Should You Eat on Intermittent Fasting 20/4?

There are no specific serving sizes on the warrior diet nor are there any set calorie restrictions (22). However, you could try cutting your daily calorie intake by 500 to 1000 calories a day, as this ordinarily leads to a weight loss of 1 to 2 pounds a week (3).

Intermittent Fasting 16/8 vs. 20/4: Which One Should You Try?

If you are a beginner, the 16/8 method would be better for you than jumping headfirst into the intermittent fasting 20/4 method. Unlike the latter, the former (16/8 method) gives you less time to fast, translating into a longer feeding window. Once your body gets used to the 16:8 variation, then you could choose to attempt a 20/4 intermittent fasting meal plan.

How Much Weight Can You Lose on a 20/4 Intermittent Fasting?

Since there is not much research on the warrior diet, it is hard to determine how much weight one can lose on this diet. However, remember that healthy weight loss is one that allows you to lose no more than 1 to 2 pounds a week.

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The Bottom Line: Should You Try the Intermittent Fasting 20/4 Method?

This method is quite an extreme and restrictive eating pattern that is not based on any scientific research. In light of this, we would advise you against trying the warrior diet. Instead, you could try other intermittent fasting variations, like the popular and less restrictive 16:8 method.

With that said, remember that fasting is not what leads to weight loss. To shed those extra pounds, you need to work out at least 30 minutes a day and eat on a 500 to 1000 calorie deficit diet. Irrespective of the kind of fasting method you choose, intermittent fasting 20/4, or other variations, please be sure to first consult a doctor for professional advice.

Apart from following a proper diet, physical exercise is also essential for your body and health. Take up a challenge and try this 20-min Full Body Workout At Home to get a snatched body.


This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. A licensed physician should be consulted for diagnosis and treatment of any medical conditions. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!


  1. A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults (2009, ncbi.nlm.nih.gov)
  2. Balanced Diet (2020, healthline.com)
  3. Counting calories: Get back to weight-loss basics (2020, mayoclinic.org)
  4. Dark Green Leafy Vegetables (2013, ars.usda.gov)
  5. Dietary fiber: Essential for a healthy diet (2018, mayoclinic.org)
  6. Effects of intermittent fasting on health markers in those with type 2 diabetes: A pilot study (2017, ncbi.nlm.nih.gov)
  7. Fasting Increases Risk for Onset of Binge Eating and Bulimic Pathology: A 5-Year Prospective Study (2010, ncbi.nlm.nih.gov)
  8. Health benefits of oily fish (2017, medicalnewstoday.com)
  9. How Protein Can Help You Lose Weight Naturally (2017, healthline.com)
  10. Intermittent Fasting Alleviates the Increase of Lipoprotein Lipase Expression in Brain of a Mouse Model of Alzheimer’s Disease: Possibly Mediated by β-hydroxybutyrate (2018, pubmed.ncbi.nlm.nih.gov)
  11. Intermittent Fasting Protects against Alzheimer’s Disease Possible through Restoring Aquaporin-4 Polarity (2017, ncbi.nlm.nih.gov)
  12. Legumes: Health Benefits and Culinary Approaches to Increase Intake (2014, ncbi.nlm.nih.gov)
  13. Non-starchy Vegetables (n.d, diabetes.org)
  14. Nutritional Deficiencies (Malnutrition) (2019, healthline.com)
  15. Role of Intermittent Fasting on Improving Health and Reducing Diseases (2014, ncbi.nlm.nih.gov)
  16. Seven Ways to do Intermittent Fasting (2020, medicalnewstoday.com)
  17. Simple Carbohydrates vs. Complex Carbohydrates (2020, healthline.com)
  18. Should I eat just one meal a day? (2020, medicalnewstoday.com)
  19. Starchy Vegetables and How to Enjoy Them (2020, verywellhealth.com)
  20. Therapeutic use of intermittent fasting for people with type 2 diabetes as an alternative to insulin (2018, pubmed.ncbi.nlm.nih.gov)
  21. The 13 Healthiest Leafy Green Vegetables (2019, healthline.com)
  22. The Warrior Diet: Review and Beginner’s Guide (2018, healthline.com)
  23. The Warrior Diet Is an Intermittent Fasting Plan for Weight Loss—but Is It Healthy? (2020, health.com)
  24. Top 12 healthful fruits (2019, medicalnewstoday.com)
  25. Vegetables and Fruits (n.d, hsph.harvard.edu)
Clare Kamau

Clare Kamau

Clare is an excellent and experienced writer who has a great interest in nutrition, weight loss, and working out. She believes that everyone should take an interest in health and fitness, as not only do they improve your way of life, but they can also have a significant impact on your health.
As a writer, her goal is to educate her readers about the ways they can reprogram themselves to enjoy exercise, as well as break free from bad eating habits. In her articles, Clare tries to give advice which is backed by scientific research and is also easy to follow on a day-to-day basis. She believes that everyone, no matter their age, gender, or fitness level, can always learn something new that can benefit their health.

Kristen Fleming

Kristen Fleming

I am a U.S. educated and trained Registered Dietitian (MS, RD, CNSC) with clinical and international development experience. I have experience conducting systematic reviews and evaluating the scientific literature both as a graduate student and later to inform my own evidence-based practice as an RD. I am currently based in Lusaka, Zambia after my Peace Corps service was cut short due to the COVID-19 pandemic and looking for some meaningful work to do as I figure out next steps. This would be my first freelance project, but I am a diligent worker and quite used to independent and self-motivated work.

Kristen Fleming, MS, RD, CNSC

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