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Intermittent fasting
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Warrior Diet: 20/4 Intermittent Fasting

"Nora Minno is an award-winning New York-based registered dietitian, certified dietitian nutritionist, and certified personal trainer specializing in wellness communications and marketing. For over ten years, she has consulted for several national publications and CPG companies, offering the latest advice in nutrition and fitness, and appears regularly on the Emmy-nominated Daily Burn 365 as well as the DailyBurn HIIT app."

Intermittent fasting is nothing new. Although it has been growing in popularity as a modern eating practice, people have been fasting for centuries for both religious and medical reasons. In fact, the practice of fasting for medical benefits can be traced back to ancient Greece when Hippocrates would recommend abstaining from food in order to treat certain illnesses [1].

Some even reference intermittent fasting back thousands of years to our ancient ancestors, who were forced to fast due to the demands of their hunter-gatherer lifestyle. There were no grocery stores or drive-throughs open 24 hours per day!

This lifestyle of our ancient ancestors is the basis for the Warrior Diet.

What is the Warrior Diet?

The Warrior Diet is a type of intermittent fasting plan designed to mimic the eating and fasting patterns of ancient warriors. Originally developed by a former member of the Israeli Special Forces, Ori Hofmekler in the early 2000’s [2], the Warrior Diet encourages you to tap into your inner “warrior instinct” and to retrain your body to align with its “natural instincts.” According to Hofmekler, this means consuming one meal per day, typically in the evening hours and fasting or eating only a small number of calories throughout the remainder of the day. This “warrior fasting” aligns with the notion that ancient warriors ate little during the day as they were moving about, then feasted at night.

You may have also the Warrior Diet referred to as the 20:4 intermittent fasting method – meaning you are eating nothing for 20 hours per day (or consuming a very small number of calories), then have a four-hour window to eat.

Another way to think of the Warrior Diet is as eating one large meal per day. Holfmekler even says that you could eat the equivalent of 3 meals per day in your one meal seating!

To boil it all down, the gist of the “Warrior Diet Principle” is based on a daily cycle of undereating and overeating. According to Hofmekler, this is no “quick fix diet”, but a lifestyle, much like other intermittent fasting plans.

20 Hour Fast Benefits

According to Hofmekler, some of the health goals of practicing the Warrior Diet include:

  • Burning fat
  • Gaining strength
  • Accelerating metabolism
  • Bosting virility
  • Detoxifying the body
  • Slowing the aging process

However, it’s important to note that there is very little research to prove these as the benefits of the Warrior Diet, particularly in human studies, and that many of Hofmekler’s suggestions are based on scientific theories rather than proven facts.

There are, however, some studies that have looked at the 20:4 intermittent fasting model and other similar models, such as the 16:8 intermittent fasting method. These studies have found some benefits of intermittent fasting to include:

  • Improvements in body composition: retaining lean muscle while reducing body fat (for those who practiced resistance training regularly) [3]
  • Weight loss [4]
  • Reduced inflammation [5]
  • Protection against Alzheimer’s disease [6][7] (found in animals)
  • Blood sugar management [8]

It’s important to note that some of these intermittent fasting studies were done on animals, therefore more studies are needed to confirm the 20:4 fasting results in humans. It’s also important to note that there aren’t any long-term studies that evaluate the benefits of the Warrior Diet for humans.

Many people who practice intermittent fasting do report additional positive effects such as feeling more energized, more alert, and many even report a reduction in hunger over time.

20:4 Fasting: What to eat and what to avoid

Most intermittent fasting plans, like the 16:8 diet, focus on when to eat, rather than what to eat. While the Warrior Diet focuses on when to eat as well, this diet does have specific guidelines on which foods to eat during your 20-hour “fasting” window, as well as guidelines on how to phase into the 4-hour eating window.

First, it’s important to understand the 2 main parts of the Warrior Diet:

1) The Undereating Phase: This is the 20-hour fasting window when Hofmekler suggests that you practice “controlled fasting.” This means you can consume some foods, just in significantly smaller quantities than a typical day of eating. According to Hofmekler, the goal of this phase is to “detoxify and cleanse, to manipulate your hormones to reach maximum metabolic efficiency, and to burn fat.”

During this fasting phase of the Warrior Diet, Hofmekler suggests consuming only a small amount of:

  • Raw fruits and vegetables (mainly as fresh juices)
  • Poached or Boiled Eggs
  • Cottage Cheese or Whey Protein
  • Plain Yogurt
  • Kefir
  • Sashimi
  • Raw nuts

In his book, Hofmekler emphasizes the importance of only consuming a small amount of protein, fruits, and vegetables during the undereating and fasting phase so your digestive system can rest, and so you can reap the Warrior Diet results.

Hofmekler also says that during the undereating phase you can drink:

  • Coffee (without sugar and only small amounts of milk)
  • Tea (without sugar or sugar substitutes)
  • Water

According to Hofmekler, it is important to avoid carbohydrates (other than fresh fruits and vegetables) during your undereating phase. Carbohydrates to avoid include:

  • Breads
  • Cereals
  • Muffins
  • Pastas
  • Corn
  • Potatoes
  • RiceBarley
  • Any sweets or foods with refined sugar (i.e. candy, pastries, cookies, ice cream, and other sweets)

Some may choose to fully abstain from all food during the undereating phase, but being able to consume small amounts of protein, fruits, and vegetables may make the Warrior Diet easier to adhere to and more appealing than stricter fasting practices.

2)   The Overeating Phase: This is the four-hour eating window in the evening in which you are encouraged to consume large amounts of food. According to Hofmekler, the goal of this phase is to repair tissues and muscle, boost metabolism, replenish energy stores, nourish your body and mind, experience guilt-free freedom while eating, and finally, retrain yourself to eat instinctively.

Hofmekler clearly outlines his suggestions on how to eat during this phase:

  • First: Start with subtle-tasting foods then more to more aggressive foods. For example, start with a salad of raw veggies before moving to cooked foods like vegetables, proteins, and carbohydrates.
  • Second: Include a wide variety of tastes, textures, colors, and aromas into your main meal.
  • Third: Stop eating when you feel more thirsty than hungry.

Since you are fasting most of the day and only have a short window to nourish your body while on the Warrior Diet, it is recommended to focus on nutrient-dense foods that provide plenty of important macro and micronutrients to the body. For example, consuming fats from avocados rather than potato chips would be recommended so your body can also get the benefits of the fiber, protein, vitamins, and minerals that come with the avocado.

If this all seems like a bit much, don’t worry, Hofmekler has outlined his recommendations for how one should phase into the Warrior Diet over a three-week period.

Phasing Into the Warrior Diet:

Week 1: Detox

  • 20-hour undereating period: consume vegetable juices, clear broth, diary, hard-boiled eggs, plain yogurt, and raw fruits and vegetables
  • 4-hour overeating period: first, have a salad with oil and vinegar, then consume a larger meal comprised of plant proteins (i.e. lentils, kidney beans, edamame, etc), wheat-free whole grains, and small portions of cooked vegetables, and cheese
  • Fluids: You can consume coffee, tea, water, and small amounts of milk during the day

Week 2: High Fat

  • 20-hour undereating period: consume vegetable juices, clear broth, diary, hard-boiled eggs, and raw fruits and vegetables
  • 4-hour overeating period: first, have a salad with oil and vinegar, then consume a larger meal comprised of lean animal proteins, cooked vegetables, and nuts (at least one handful). You are also allowed other proteins such as eggs, yogurt, kefir, ricotta cheese, feta cheese, goat cheese, or Parmesan cheese. It is recommended to avoid any grains or starches during this period.
  • Fluids: You can consume coffee, tea, water, and small amounts of milk during the day

Week 3: Fat Loss

This phase of the Warrior Diet is slightly different in that it cycles between 1-2 high-protein days and 1-2 high-carbohydrate days until the week is complete.

High-Carb Days:

  • 20-hour undereating period: consume vegetable juices, clear broth, diary, hard-boiled eggs, and raw fruits and vegetables
  • 4-hour overeating period: first, have a salad with oil and vinegar, then consume a larger meal comprised of cooked vegetables, a small amount of lean animal proteins, and on main source of carbohydrates such as potatoes, pasta, barley, oats, corn, peas, or quinoa.
  • Fluids: You can consume coffee, tea, water, and small amounts of milk during the day

High-Protein Days:

  • 20-hour undereating period: consume vegetable juices, clear broth, diary, hard-boiled eggs, and raw fruits and vegetables
  • 4-hour overeating period: first, have a salad with oil and vinegar, then consume a larger meal comprised of protein and cooked non-starchy vegetables. No starches or grains are allowed on these days.
  • Fluids: You can consume coffee, tea, water, and small amounts of milk during the day

Once you have completed the 3 phases, Hofmekler recommends beginning again at phase 1 and cycling through each phase of the intermittent fasting plan again. One could also skip over the phases and follow the general guidelines of undereating/fasting for 20 hours, then consuming protein-rich meals during the 4-hour eating window.

Potential downfalls of the Warrior Diet

As mentioned before, there are no studies that look at the long-term effects of the Warrior Diet, therefore, more research is needed to fully understand how the Warrior Diet affects humans over time.

While there are many potential benefits of the 20:4 fasting method, there are some potential downfalls as well.

1. Difficulty With Long Term Compliance of the Warrior Diet
It’s not hard to see how sticking to a 20:4 model long-term could be difficult. With many social activities revolving around food – it would be difficult to join friends to lunch or have a business breakfast when fasting during the daytime.

Also, with the prolonged fasting period, many may feel tired, hungry, or irritable during the day and choose to revert to a more regular eating pattern before their body fully adjusts to the 20:4 fasting model.

2. The Warrior Diet Is Not for Everyone

There are certain populations of people that may benefit from the Warrior Diet, however, there are other populations that this type of fasting is not recommended for such as:

  • Pregnant or nursing women
  • Children
  • People with certain chronic diseases such as type 1 diabetes, certain types of cancer, and certain types of heart disease
  • Athletes with demanding training or competition regimens
  • People with a history of eating disorders or disordered eating habits
  • People who are underweight or at risk for malnourishment due to various conditions

It’s also important to note that while on the Warrior Diet, some people may experience symptoms of:

  • Fatigue
  • Dizziness/Lightheadedness/Fainting
  • Anxiety
  • Hunger
  • Low Energy
  • Low Blood Sugar
  • Irritability
  • Hormonal imbalances
  • Weight gain

As always, be sure to consult with your doctor before starting any new diet, especially one that may vary greatly from your current eating regimen. You could also consult a registered dietitian to help you with a 20:4 intermittent fasting meal plan to ensure that you are getting adequate nutrition while reaping the potential Warrior Diet results you are seeking.

[1] https://www.britannica.com/topic/fasting

[2] https://www.orihofmekler.com/ 

[3] https://www.mdpi.com/2072-6643/12/4/1126/htm 

[4] https://pubmed.ncbi.nlm.nih.gov/32060194/

[5] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5064803/ 

[6] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5712566/

[7] https://pubmed.ncbi.nlm.nih.gov/29386999/

[8] https://www.sciencedirect.com/science/article/pii/S1550413118302535

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