What foods are allowed in the Warrior Diet undereating phase? A complete guide

October 5, 2025 •

3 min read

Over two decades after its creation, the Warrior Diet remains a popular form of intermittent fasting. It's a diet with a strict 20:4 eating pattern, which raises the crucial question: what foods are allowed in the Warrior Diet undereating phase? This extended fasting period is central to the diet's philosophy and success.

Quick Summary

The Warrior Diet's 20-hour undereating phase permits small amounts of low-calorie, nutrient-dense foods. Acceptable options include raw fruits, vegetables, vegetable juices, clear broths, hard-boiled eggs, and some dairy, alongside non-caloric beverages. The goal is to sustain energy and curb hunger until the main evening meal.

Key Points

Raw Produce: Small portions of raw fruits like berries and apples, along with raw vegetables like carrots and greens, are permitted during the undereating phase.
Light Protein: Acceptable protein sources include hard-boiled eggs and small servings of plain yogurt or cottage cheese.
Clear Liquids: Unsweetened coffee, tea, water, vegetable juices, and broth are encouraged to maintain hydration and manage hunger.
Avoidance of Processed Foods: Fried foods, sugary drinks, grains, and starches should be completely avoided during the 20-hour window.
Purposeful Undereating: The goal is to provide essential nutrients and curb hunger with minimal calories, preventing a large insulin spike.
Hydration is Key: Drinking plenty of water and other allowed fluids is crucial for managing the 20-hour period effectively.

The Warrior Diet, developed by Ori Hofmekler, follows a rigorous 20-hour period of 'undereating' followed by a four-hour 'overeating' window. Inspired by the eating patterns of ancient warriors, this schedule is designed to optimize fat metabolism and energy levels. The undereating phase, sometimes referred to as the fasting period, is not a full fast. It allows for small portions of specific foods to provide sustained energy and curb hunger pangs without initiating a significant insulin response.

Permitted foods during the undereating phase

During the 20-hour undereating window, the focus is on raw, whole, and minimally processed foods that are low in calories. These choices are meant to provide vitamins and minerals without breaking the fast in a meaningful way. Here’s a breakdown of what you can consume:

Raw fruits and vegetables

Small portions of raw fruits and vegetables are staples of the undereating phase. These provide fiber, vitamins, and a natural sugar source that is less likely to cause a large insulin spike. Examples include:

Fruits: Apples, bananas, peaches, kiwis, and a handful of berries.
Vegetables: Carrots, celery, bell peppers, leafy greens, and mushrooms.

Light protein sources

To help maintain muscle mass and increase satiety, small amounts of light protein are also acceptable. Options include:

Eggs: Hard-boiled or poached eggs are a perfect, portable source of protein.
Dairy: Small servings of plain yogurt, cottage cheese, or kefir are acceptable. These should ideally be from pasture-raised animals.

Nutrient-dense liquids

Liquids are essential for hydration and can help manage hunger.

Vegetable Juices: Fresh-made vegetable juices (like carrot or celery) are permitted, but avoid sugary, store-bought varieties.
Broth: Clear, homemade chicken or beef broth can help replenish electrolytes and minerals without adding many calories.
Protein Shakes: A low-calorie, all-natural whey protein shake can be used, mixed with water.

Allowed beverages and condiments

Proper hydration is critical during any fasting period. In the Warrior Diet, this means consuming plenty of fluids.

Beverages

Water: Water is the most important fluid and should be consumed freely.
Coffee and Tea: Unsweetened coffee and tea are allowed and can help boost metabolism and suppress appetite.
Other options: Seltzer water is also a good choice.

Condiments

Olive Oil and Vinegar: Small amounts can be used for dressing a small salad.

Comparison of allowed vs. restricted foods

To ensure success with the Warrior Diet, it's vital to differentiate between acceptable and unacceptable food options during the undereating phase. The following table provides a clear comparison.


Food Type	Allowed During Undereating Phase	Restricted During Undereating Phase
Produce	Raw fruits and vegetables	Cooked vegetables, fruit juice from concentrate
Protein	Hard-boiled eggs, small dairy servings	Large portions of meat, processed meats, fried eggs
Dairy	Plain yogurt, cottage cheese, kefir	Flavored yogurt, ice cream, high-sugar dairy products
Beverages	Water, coffee, tea, vegetable juice	Sugary drinks, alcoholic beverages, sweetened coffee
Carbohydrates	Minimal amounts from raw produce	Grains, starches, pasta, bread, sugary snacks
Fats	Small amounts of olive oil	Fried foods, fatty meats, nuts (high-calorie)

The rationale behind the food choices

The choices of permitted foods during the undereating phase are purposeful, aiming to provide minimal calories while delivering essential nutrients. Hofmekler's philosophy encourages consuming foods that an ancient hunter-gatherer might have foraged during the day. Raw produce, in particular, requires more energy to digest, contributing to a feeling of fullness without a high caloric intake. The small protein and dairy portions are designed to keep the metabolism active and provide steady energy, preventing a complete calorie crash and making the 20-hour window manageable. This approach contrasts with zero-calorie fasting by offering a more sustainable way to extend the fasting period while reaping potential health benefits, such as improved insulin sensitivity and increased fat metabolism. For a more detailed breakdown of the overall diet, you can refer to authoritative sources like Verywell Fit.

Conclusion

Understanding what foods are allowed in the Warrior Diet undereating phase is the first step towards successfully implementing this intermittent fasting plan. The key is to stick to small portions of raw fruits and vegetables, light proteins like eggs or plain dairy, and calorie-free beverages. By making deliberate, nutrient-dense choices during this period, followers can manage hunger effectively and prepare their bodies for the main feasting window, aligning with the diet's core principles and objectives.

Frequently Asked Questions

No, the undereating phase generally restricts you to small amounts of raw fruits and vegetables, light proteins like eggs, and broth. Cooked foods are reserved for the main four-hour eating window.

While there is no specific calorie limit, the intention is to consume minimal calories from the allowed foods. The portions should be small, just enough to curb hunger and provide some nutrients.

No, the Warrior Diet emphasizes whole, unprocessed foods and beverages. Artificial sugars and additives found in diet sodas are not aligned with the diet's philosophy.

Some variations permit a small, low-calorie whey protein shake mixed with water. However, the core principle is to keep calories minimal, so a full, high-calorie shake might be too much.

Clear soup broths, such as chicken or beef, are permitted. These should be homemade to avoid excessive salt, MSG, and hydrogenated oils often found in packaged options.

No, during the undereating phase, coffee and tea should be unsweetened. The goal is to avoid sugar and artificial sweeteners that can disrupt the fasting process.

While many raw fruits are acceptable, it's best to stick to low-to-moderate sugar options like berries. High-sugar fruits in large quantities could cause a significant insulin spike.