How long do you fast on the Warrior Diet?

December 15, 2025 •

3 min read

According to its founder, Ori Hofmekler, the Warrior Diet is a form of intermittent fasting based on the eating habits of ancient warriors. The core principle of the diet revolves around a 20-hour period of undereating, followed by a 4-hour 'overeating' window. Knowing how long do you fast on the Warrior Diet is the first step toward understanding this unique eating pattern.

Quick Summary

The Warrior Diet centers on a daily 20-hour undereating phase and a 4-hour eating window. Followers consume small amounts of specific foods like raw fruits and vegetables during the day before having a larger, nutrient-dense meal in the evening. This extreme intermittent fasting method is considered challenging and potentially unsuitable for many people, especially beginners.

Key Points

20-Hour Fasting Period: The core of the Warrior Diet is a 20-hour phase of minimal calorie intake, allowing only small amounts of raw produce, some protein, broth, and zero-calorie fluids.
4-Hour Eating Window: This fasting period is followed by a concentrated 4-hour window for consuming the majority of the day's calories, focusing on whole, unprocessed, and nutrient-dense foods.
Nutrient-Dense Feasting: The feasting period emphasizes a large, nutrient-dense meal of lean proteins, healthy fats, cooked vegetables, and whole grains.
Potential Risks: The Warrior Diet is considered extreme and may lead to side effects like fatigue, dizziness, and nutrient deficiencies; it is not recommended for everyone.
Expert Caution: Health professionals advise caution due to the diet's restrictiveness and potential to trigger disordered eating patterns.
Alternative Methods: Less extreme intermittent fasting methods, like the 16:8 approach, may be more suitable and sustainable for beginners.

The 20-Hour Undereating Phase

At the heart of the Warrior Diet is the prolonged 20-hour daily fasting period. Unlike traditional calorie-free fasting, this phase allows for small amounts of specific raw, organic foods to sustain energy and manage hunger. Followers are encouraged to consume raw fruits, vegetables, and small portions of protein, such as hard-boiled eggs or cottage cheese. Non-caloric beverages like water, black coffee, and unsweetened tea are also permitted throughout the day.

This prolonged daily fast is intended to align with the body's natural circadian rhythm, emphasizing activity during the day with minimal food intake, much like ancient warriors would have done. This practice supposedly builds resilience and triggers the body's 'survival instincts' for improved energy and fat burning.

What to Consume During the Fasting Window

Fluids: Water, unsweetened tea, and black coffee. Some interpretations also permit small amounts of milk.
Raw Produce: Raw fruits and vegetables in small quantities.
Limited Protein: Small portions of protein, such as hard-boiled eggs, cottage cheese, or Greek yogurt.
Broth: Vegetable or bone broth for hydration and nutrients.

The 4-Hour Eating Window

Following the 20-hour fast is a concentrated 4-hour eating window, also known as the feasting period. During this time, the majority of the day's calories are consumed in one large, nutrient-dense meal or a series of smaller ones. The dietary focus is on whole, unprocessed, organic foods. This can include lean proteins, cooked vegetables, whole grains, healthy fats from nuts, and dairy.

The feast is a critical part of the diet, aimed at replenishing nutrients and repairing the body after the extended fast. Hofmekler's original guidance encourages consuming a salad first, followed by protein and other whole food choices. The diet also incorporates specific phases that dictate the macronutrient balance during the eating window, such as high-fat and high-carb days.

Comparing the Warrior Diet to Other Intermittent Fasting Methods

The Warrior Diet is an intense version of intermittent fasting (IF), with a shorter, more restrictive eating window than other popular methods. The table below highlights key differences.


Feature	Warrior Diet (20:4)	16:8 Intermittent Fasting	One Meal A Day (OMAD)	Alternative-Day Fasting (ADF)
Fasting Period	20 hours daily	16 hours daily	Typically 22-23 hours daily	24-36 hours, every other day
Eating Window	4 hours daily	8 hours daily	1-2 hours daily	No eating window on fasting days
Calorie Intake During Fast	Small amounts of specific raw foods are allowed.	Zero- or low-calorie drinks only.	None, or very minimal calories.	None on fasting days.
Difficulty	High	Moderate	Very High	High
Sustainability	Challenging for most people.	Often considered more sustainable.	Very difficult for most.	Can be managed by some.

Important Considerations and Risks

While rooted in the broader concept of intermittent fasting, the Warrior Diet is not without its controversies and risks. Some experts consider its strict 20:4 protocol extreme and unnecessary for most people. The diet's emphasis on overeating can potentially lead to disordered eating patterns, particularly in susceptible individuals.

Furthermore, the small eating window can make it challenging to consume a balanced, nutrient-dense diet, potentially leading to nutritional deficiencies if not planned carefully. Side effects such as fatigue, dizziness, irritability, and anxiety are commonly reported, especially during the initial adjustment period. It is important to note that the diet lacks specific scientific research to support its unique methods, though studies on general intermittent fasting do exist.

For most people, particularly beginners, less restrictive forms of intermittent fasting, such as the 16:8 method, are recommended as a starting point. Consulting a healthcare provider before beginning any new diet, especially one as restrictive as the Warrior Diet, is crucial to ensure it aligns with your health needs and goals. For more general information on fasting, visit the National Institutes of Health website.

Conclusion

To answer the question of how long you fast on the Warrior Diet, the standard duration is 20 hours. This is followed by a 4-hour eating window during which the day's calories are consumed. The fasting phase allows for minimal calories from raw fruits, vegetables, and small amounts of protein to help curb hunger. While some benefits of intermittent fasting may apply to this plan, its extreme nature makes it a challenging and potentially unsustainable approach for many. It is crucial to weigh the risks and benefits and to consult a professional before embarking on such a restrictive regimen.

Frequently Asked Questions

The core principle of the Warrior Diet is to have a 20-hour period of fasting or 'undereating' followed by a 4-hour eating window.

During the fasting period, you can consume non-caloric fluids such as water, black coffee, or unsweetened tea. Small amounts of raw fruits, vegetables, and some protein like hard-boiled eggs or dairy are also permitted.

No, the Warrior Diet is not a true zero-calorie fast. It allows for minimal calorie intake from specific foods during the 20-hour period, which differentiates it from stricter fasting protocols.

The eating window should focus on consuming unprocessed, whole foods, including a good balance of lean proteins, healthy fats, and nutrient-dense carbohydrates.

No, the Warrior Diet is often considered too extreme for beginners. Health experts recommend starting with a less restrictive form of intermittent fasting, such as the 16:8 method.

Weight loss is possible on the Warrior Diet, as the restrictive eating window often leads to a natural reduction in overall calorie intake. However, it is not scientifically proven to be more effective for weight loss than general calorie restriction.

Common side effects include fatigue, dizziness, irritability, anxiety, and extreme hunger, especially when first adjusting to the strict schedule.