What Can You Eat While Fasting Intermittent Fasting: Your Comprehensive Guide

December 12, 2025 •

3 min read

Research from Johns Hopkins neuroscientist Mark Mattson, who has studied the practice for 25 years, indicates that intermittent fasting prompts a 'metabolic switch,' causing the body to transition from burning glucose to burning fat for energy. Knowing what can you eat while fasting intermittent fasting is essential for supporting this process and reaping the full benefits.

Quick Summary

This guide provides a definitive breakdown of food choices for intermittent fasting. Learn what beverages are permitted during the fast and the optimal nutrient-dense foods for your eating window.

Key Points

Stay Hydrated with Calorie-Free Drinks: During your fast, stick to plain water, black coffee, or unsweetened tea to avoid breaking the fasted state.
Prioritize Whole, Nutrient-Dense Foods: Focus on lean proteins, healthy fats, and fiber-rich fruits and vegetables during your eating window to maximize health benefits.
Avoid Sugary and Processed Foods: High-sugar drinks and ultra-processed snacks can negate the positive effects of intermittent fasting and cause energy crashes.
Break Your Fast Gently: Start your eating window with smaller, easily digestible, and nutrient-dense foods like cooked vegetables or eggs to ease your digestive system back into action.
Plan Your Meals in Advance: Meal preparation helps ensure you make healthy choices during your eating window and prevents overeating or poor food selections.
Listen to Your Body: Pay attention to hunger and fullness cues to avoid overconsumption and adjust your eating habits according to your individual needs.

Intermittent fasting is an eating pattern that cycles between periods of voluntary fasting and non-fasting over a set period. While the timing of your meals is central to this practice, the quality and type of food you consume during your eating window are equally important for achieving your health goals.

What to Consume During Your Fasting Window

For most intermittent fasting protocols, the fasting window is a period of abstaining from all caloric intake to keep insulin levels low and encourage fat burning. However, some exceptions will not break a strict fast or significantly hinder the process.

Fast-Friendly Beverages

Staying hydrated is crucial during fasting periods. Safe, zero-calorie options include:

Plain Water: Still and sparkling water are acceptable for hydration.
Black Coffee: With minimal calories, black coffee is generally considered safe and may suppress appetite. Avoid sugar, milk, or cream.
Unsweetened Tea: Plain tea (green, black, or herbal) is calorie-free and green tea may offer additional benefits.
Diluted Apple Cider Vinegar: A small amount in water won't break a fast and may offer health benefits.
Bone Broth: Some modified fasts allow a small amount to help with electrolytes, although it's a gray area for strict fasting.

Fueling Your Eating Window: The Best Food Choices

Nutritious choices during your eating window are crucial for success in intermittent fasting. A diet rich in whole foods, like the Mediterranean diet, is recommended.

Prioritize Lean Proteins

Protein helps build muscle and promotes fullness. Good sources include:

Lean Meats and Poultry
Fish and Seafood, especially fatty fish with omega-3s
Eggs
Legumes
Dairy like Greek yogurt or cottage cheese

Incorporate Whole Grains for Sustained Energy

Whole grains provide complex carbohydrates and sustained energy. Options include:

Oats and Quinoa
Brown Rice
Whole-Grain Bread and Pasta

Load Up on Fruits and Vegetables

These are rich in vitamins, minerals, and fiber, aiding digestion and satiety.

Leafy Greens
Berries for antioxidants and natural sweetness
Cruciferous Vegetables for fiber
Avocado for healthy fats and nutrients

Include Healthy Fats

Healthy fats are important for cellular health, hormones, and satiety. Sources include:

Olive Oil
Nuts and Seeds

The Foods and Drinks That Break a Fast

Any caloric intake triggers an insulin response and breaks a fast. Be aware of hidden calories.

Sugary Drinks (sodas, juices)
Milk and Creamers (dairy or plant-based)
Sugary Snacks
Processed Carbohydrates (white bread, pasta)
Supplements with Additives (gummies, protein powders)

Intermittent Fasting vs. Traditional Diets: A Comparison


Feature	Intermittent Fasting	Traditional Calorie-Restriction Diets
Primary Focus	When you eat	What and how much you eat
Key Mechanism	Time-restricted eating to promote metabolic switching	Calorie deficit created over the entire day
Flexibility	High degree of flexibility in scheduling eating windows	Constant focus on calorie counting and tracking
Metabolic Impact	Can boost metabolism by increasing norepinephrine levels	Can sometimes lead to a slower metabolism over time
Meal Timing	Structured and specific eating and fasting windows	Typically involves 3 main meals and 1-2 snacks
Psychological Effect	Can simplify eating decisions and reduce mental load	Can lead to feelings of deprivation and burnout

How to Break Your Fast Gently

Ease back into eating to avoid digestive discomfort. Start with small, easily digestible meals such as:

A Small Salad
Cooked Vegetables
Eggs or Avocado
Bone Broth-Based Soup

Transition to your regular, nutritious meal after this gentle start. Listen to your body and prioritize nutrient-dense foods. Learn more about intermittent fasting benefits from Johns Hopkins Medicine: https://www.hopkinsmedicine.org/health/wellness-and-prevention/intermittent-fasting-what-is-it-and-how-does-it-work.

Conclusion

Knowing what can you eat while fasting intermittent fasting is key to success. Focus on calorie-free drinks during the fast and nutrient-dense, whole foods during your eating window to support fat-burning, improve metabolic health, and achieve wellness. Avoid processed and sugary items that hinder fasting efforts. Careful planning and mindful eating make intermittent fasting a sustainable lifestyle.

Frequently Asked Questions

Most supplements will break a fast, especially gummies or protein powders that contain calories or sugar. Individual vitamins and minerals that are calorie-free may be acceptable, but it's often best to take them with a meal for better absorption.

Technically, yes, bone broth contains calories and protein, which can technically break a fast. However, for those focused on metabolic health rather than strict autophagy, a small amount is sometimes permitted to help curb cravings and replenish electrolytes without causing a significant insulin spike.

No, adding any form of sugar, milk, or cream to your coffee or tea will break your fast. These additives contain calories that will trigger an insulin response and take your body out of the fasted state.

Accidentally consuming a small amount of food will likely not derail your overall progress. Simply acknowledge the mistake and return to your fasting schedule. Consistency over time is more important than a single perfect day.

It is not recommended to eat a large, heavy meal immediately after fasting. This can cause bloating, digestive discomfort, and a sudden blood sugar spike. Instead, ease back into eating with a smaller, nutrient-dense meal and build up from there.

Artificial sweeteners are a debated topic. While they are calorie-free, some research suggests they can still trigger an insulin response or increase cravings. It's safest to stick to unsweetened beverages like plain coffee or tea during your fast to ensure no insulin response occurs.

Staying well-hydrated with plenty of water can help manage hunger. Some people find that sipping black coffee or herbal tea also helps. Staying busy and distracted is another effective strategy for getting through the fasting period.