A Guide To The 20:4 Fast

Interested in intermittent fasting? There are lots of options, like the 20:4 plan. This beginner's guide covers the 20:4 method, its health benefits, and tips for doing it right.

The 20/4 fast, also known as the Warrior Diet, means not eating for 20 hours and then eating for 4 hours each day. It’s known for helping with weight loss, getting stronger, and better heart health. But, it’s a tough and strict way to eat that may not work for everyone.

What is the 20:4 Method? ๐Ÿ‘€

The 20:4 fast, also known as the Warrior Diet, was created by health expert Ori Hofmekler in 2001.

Inspired by ancient warriors, it involves fasting for 20 hours (or eating very little) and then eating 90% of your calories in a 4 hour window.

It’s based on the concept that our ancient ancestors spent their days actively hunting and gathering, and then ate mainly in the evening. The idea is that eating in line with this pattern can help the body better use nutrients, following the natural circadian rhythm.

During this window, you can eat whatever you’d like (within your daily calories) โ€“ but it’s a good idea to focus on filling and nutritious foods.

Intermittent fasting involves scheduled periods of not eating to improve health and manage weight. It’s not about cutting out specific foods or counting calories per say, but rather changing when you eat. This approach helps in weight loss, disease prevention, better brain function, and might even extend life.

Before You Start 20:4 โ€“ Do This โ˜๐Ÿฝ

Hofmekler recommends you follow a three-week, three-phase plan initially before starting the Warrior Diet. This helps the body adapt to the eating and fasting schedule and become accustomed to using body fat as energy. This three-week introduction includes:

Phase 1 โ€“ โ€œDetoxโ€

  • 4-hour evening eating period: consume salad with a dressing and a large or a couple of smaller meals of plant protein, whole grains, cheese and cooked vegetables.
  • 20-hour fast: consume vegetable juices, bone broth, yoghurt, cottage cheese, hard-boiled eggs, raw fruit and raw vegetables. Black coffee, tea, water and small portions of milk can be consumed during the fasting period.

Phase 2 โ€“ โ€œHigh Fatโ€

  • 4-hour evening eating period: consume salad with a dressing and a large meal of lean animal protein, cooked vegetables and a handful of nuts. Grains and starches are eliminated in this dieting phase.
  • 20-hour fast: consume vegetable juices, bone broth, yoghurt, cottage cheese, hard-boiled eggs, raw fruit and raw vegetables.’

Phase 3 โ€“ โ€œConcluding Fat Lossโ€

  • On the high carb days: Consume as above in phase 2 with the addition of one main carbohydrate such as potatoes, pasta or oats.
  • On the high protein days: Consume as above in phase 2 including 227-454 grams of animal protein and a side of cooked, non-starchy vegetables.

TIP: Do the 3-phase diet TWICE before following the 20:4 guidelines.


Depending on your goals, you may only adopt the 20:4 fasting method three times per week rather than making it a daily habit.

A Sample Day of a 20:4 Fast

Morning Feeding Window (8am-12pm)

  • 8 a.m: Greek yogurt with mixed berries and honey.
  • 8:30 a.m: Workout.
  • 9:30 a.m: Whole grain toast with peanut butter and banana slices.
  • 11 a.m: Spinach and mango smoothie.
  • 12 p.m: Tuna salad with mixed greens and vinaigrette.

Midday Feeding Window (2pm-6pm)

  • 2 p.m: Quinoa bowl with roasted veggies and chickpeas.
  • 3 p.m: Cottage cheese with pineapple chunks.
  • 4 p.m: Carrot sticks with hummus.
  • 6 p.m: Baked chicken breast with quinoa and steamed broccoli.

Evening Feed Window (4pm-8pm)

  • 4 p.m: A small bowl of mixed nuts.
  • 5 p.m: Sliced cucumber and cherry tomatoes with a dollop of hummus.
  • 6 p.m: Grilled vegetable and feta cheese wrap.
  • 8 p.m: Baked salmon with a side of sweet potato mash and green beans.

Tips to Nail Your 20:4 Fast ๐Ÿ“

  1. Start Slowly: Begin with shorter fasts like 12 or 16 hours and gradually work up to 20 hours.
  2. Try Different Schedules: Mix up your meals and eating times. Maybe eat one large meal or several small ones during your eating window.
  3. Eat Healthy Foods: Choose whole foods like fruits, veggies, lean proteins, and nuts. Avoid processed and sugary foods.
  4. Plan Meals: Plan what you’ll eat in advance to avoid unhealthy choices.
  5. Stay Hydrated: Drink plenty of water and calorie-free drinks like herbal tea.
  6. Consider Supplements: A daily multivitamin might help cover any nutritional gaps while fasting.

As this is one of the more extreme methods of intermittent fasting, it is recommended you do your research before you start and even consult with a dietitian or a nutritionist to ensure it is right for you.

The best resource for the original Warrior Diet is Hofmeklerโ€™s own book The Warrior Diet: Switch on Your Biological Powerhouse for High Energy, Explosive Strength and a Leaner, Harder Body.

Health Benefits of 20:4 Warrior Diet ๐ŸŽ

Based on the available information, here are the health benefits associated with the 20:4 Warrior Diet:

  • Improved Cardiometabolic Health: May help lower weight, BMI, blood pressure, cholesterol, and triglyceride levelsโ€‹โ€‹.
  • Blood Glucose Regulation: Fasting for 20-hour intervals can aid in lowering blood glucose levels, which is beneficial for preventing diabetes and other health conditionsโ€‹โ€‹.
  • Cell Repair and Rejuvenation: Fasting can promote autophagy, a process for repairing and recycling damaged cells, potentially reducing the risk of diseases like cancer and neurodegenerative disordersโ€‹โ€‹.
  • Weight Loss: Can lead to weight loss, though the amount depends on individual eating patterns on fasting and non-fasting daysโ€‹โ€‹.
  • Potential Additional Benefits: Some believe it may also enhance cognitive function and reduce inflammation, but more studies are needed to confirm these benefits.โ€‹
  • The 20:4 isnโ€™t backed by official research. The diet was created by Ori Hofmekler and is based on his own observations and experiences during his time in the Israeli Special Forces.
  • There is no evidence directly linking a 20:4 fast with any of the benefits of intermittent fasting. Although there is some preliminary evidence that fasting on a 20-hour cycle or 24-hour fast may result in body fat loss and reduced risk of cardiovascular disease.
  • In some rats and mice studies, alternate day fasting for 24-hours did result in up to 30% overall calorie reductions, however, the results were mixed and the health benefits insignificant. The research was also not conducted using the Warrior Diet which is a daily regime.

Pros & Cons of the 20:4 Diet ๐Ÿ‘๐Ÿป ๐Ÿ‘Ž๐Ÿป

๐Ÿ‘๐Ÿป ๐Ÿ‘Ž๐Ÿป
โœ… Promotes Weight Loss: Can be effective for losing weight due to extended fasting periods.

โœ… Flexible Food Choices: Does not restrict any specific food groups.

โœ… Improves Metabolic Health: May benefit blood glucose, blood pressure, and cholesterol levels improves.

โœ… Aligns with Natural Rhythms: Mimics ancient eating patterns, potentially aligning with circadian rhythms.

โœ… Encourages Autophagy: Helps in cellular repair and detoxification.
โŒ Challenging to Sustain: Long fasting hours can be difficult to maintain long-term.

โŒ Risk of Nutrient Deficiencies: Short eating window can lead to insufficient nutrient intake.

โŒ Not Suitable for Everyone: Can be risky for pregnant women, underweight individuals, or those with certain health conditions.

โŒ Social and Lifestyle Challenges: Restrictive eating window might conflict with social events or family meals.

โŒ Potential Side Effects: May cause hunger, fatigue, irritability, and mood swings.

Side Effects and Risks of the 20:4 Diet ๐Ÿ™…๐Ÿปโ€โ™€๏ธ

Any dieting plan or fasting regime does have its side effects and risks, and there is no one plan that is suitable for everyone.

The 20:4 or Warrior Diet is one of the more extreme forms of intermittent fasting with extended periods of fasting and as such the side effects may be greater.

Some side effects of the 20:4 diet due to the duration of calorie restriction include:

  • Hunger
  • Tiredness or weakness
  • Brain fog
  • Insomnia
  • Irritability or mood swings
  • Stress or anxiety
  • Nutritional deficiencies
  • Hormone disruptions

Is the 20:4 Diet Right for YOU? ๐Ÿ‘€

Before trying the 20:4 fasting diet, it’s a good idea to talk to a doctor, especially since it involves eating less for a long time.

It’s not a great fit for:

  • Women who are pregnant or breastfeeding.
  • People under 18.
  • Anyone who’s underweight or has had eating disorders.
  • Athletes who need lots of energy.

If you’ve got health issues like diabetes or take regular medicine, definitely check with your doctor first before starting this diet.

Should You Try the 20:4 Diet? ๐Ÿคท๐Ÿพโ€โ™‚๏ธ

The 20:4 Warrior Diet is a tough fasting method and there’s no solid proof it helps with weight loss or boosts energy. It involves not eating for a long time each day and then eating a lot in a short time.

It might work for some goals, but it’s hard, especially for beginners, and can have side effects.

Before starting any fasting, it’s best to chat with a doctor. You might want to try easier fasting methods like 5:2 or 16:8 first.

Related Articles: Intermittent Fasting ๐Ÿ—’๏ธ


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