What Breaks a Fast? Complete Guide to Foods, Drinks & Supplements

Intermittent fasting has become increasingly popular as a health and wellness practice, but knowing what actually breaks a fast can be confusing. Understanding which foods, drinks, and supplements affect your fasting state is crucial for maximizing the benefits of your fasting regimen.

Whether you’re new to fasting or looking to optimize your current routine, this comprehensive guide will help you navigate what you can consume during fasting periods and how to properly break your fast without compromising your results.

Understanding What Actually Breaks a Fast

By strict definition, consuming any calories technically breaks a fast. However, the practical answer is more nuanced and depends on your fasting goals and the type of fast you’re following.

The key factor in determining whether something breaks your fast relates to how it affects your body’s metabolic state, particularly:

• Insulin response: Foods that spike insulin can interrupt the fasting state
• Caloric intake: Significant calories trigger digestive processes
• Ketosis: Some foods may maintain ketosis even with minimal calories
• Autophagy: Certain nutrients can inhibit cellular repair processes

Research suggests that consuming fewer than 50 grams of carbohydrates may allow you to maintain some fasting benefits, including ketosis. However, this varies based on individual metabolism and fasting objectives.

What You Can Safely Consume While Fasting

While true fasting means abstaining from all food, certain beverages and minimal-calorie items are generally considered acceptable during fasting windows without significantly disrupting fasting benefits.

Zero-Calorie Beverages

Water is the gold standard for fasting. Both plain and sparkling water contain zero calories and keep you hydrated without affecting your fasting state. Staying well-hydrated is essential during fasting periods to support bodily functions and help manage hunger.

Black Coffee is another fasting-friendly option. Plain coffee without additives contains virtually no calories and may even enhance some fasting benefits by increasing metabolic rate and promoting fat burning. However, avoid adding sugar, milk, cream, or flavored syrups, as these will break your fast.

Plain Tea – whether black, green, white, or herbal – contains minimal to no calories and can be consumed during fasting. Tea also provides antioxidants and may help suppress appetite. Like coffee, drink it unsweetened and without milk or cream.

Beverages in the Gray Area

Some beverages exist in a gray area where they may technically contain minimal calories but are often considered acceptable for certain fasting protocols:

Coffee or Tea with Minimal Additions: Some fasting practitioners add small amounts of fat like MCT oil, coconut oil, ghee, or butter to their coffee or tea. While this technically breaks a fast by adding calories, it may help control hunger while keeping you in ketosis. This approach is common in “fat fasting” protocols.

Apple Cider Vinegar: Diluted apple cider vinegar (1-2 teaspoons in water) contains minimal calories and may help with hydration and appetite control. Some people find it beneficial during fasting periods, though it does contain trace amounts of carbohydrates.

Bone Broth: While bone broth contains calories, protein, and nutrients, some fasting protocols allow it in small amounts. It can help replenish electrolytes during extended fasts, though it will technically interrupt pure fasting.

Supplements During Fasting: What Breaks Your Fast

Taking supplements while fasting requires careful consideration, as some can interrupt your fasting state while others have minimal impact.

Supplements That Will Break Your Fast

Certain supplements contain ingredients that trigger metabolic responses incompatible with fasting:

Gummy Vitamins: These typically contain sugar, gelatin, and sometimes added fats to create their texture and flavor. The sugar and calories will break your fast and trigger an insulin response.

Protein Powders: Whey, casein, or plant-based protein powders contain significant calories and protein that will definitely break your fast. Protein triggers insulin release and activates nutrient-sensing pathways that oppose fasting benefits. Save protein supplements for your eating window.

Branched-Chain Amino Acids (BCAAs): Despite being popular in the fitness community, BCAAs trigger an insulin response and can inhibit autophagy, one of the key benefits of fasting. Take these during your eating window instead.

Supplements with Hidden Calories: Check labels carefully for ingredients like maltodextrin, pectin, fruit juice concentrate, or cane sugar. These additives contain carbohydrates and calories that will break your fast.

Supplements Less Likely to Break Your Fast

These supplements contain minimal to no calories and are generally safe during fasting periods:

Pure Multivitamins: Capsule or tablet multivitamins without added fillers, sugar, or coatings typically contain negligible calories. However, fat-soluble vitamins (A, D, E, and K) are better absorbed with food, so you may want to take these during eating windows.

Individual Minerals and Vitamins: Electrolyte supplements like potassium, magnesium, and sodium are excellent during fasting, especially for longer fasts. Water-soluble vitamins like B-complex and vitamin C can be taken while fasting, though fat-soluble vitamins should be taken with meals for better absorption.

Fish or Algae Oil: In standard doses, these omega-3 supplements contain minimal calories that are unlikely to significantly impact your fasting state, though technically they do add some calories.

Creatine: Pure creatine monohydrate contains no calories and doesn’t affect insulin levels, making it safe to take during fasting periods.

Probiotics and Prebiotics: Most probiotic supplements contain no calories or digestible carbohydrates. However, some people prefer taking probiotics with food to support bacterial survival through stomach acid.

Pure Collagen Peptides: While collagen contains protein, it may have a minimal impact on autophagy and shouldn’t significantly affect ketosis when taken in small amounts. However, larger doses will break your fast.

Foods and Drinks That Definitely Break Your Fast

To be clear, the following will absolutely break your fast and should only be consumed during your eating window:

• Any solid foods – regardless of type or quantity
• Milk or cream in coffee or tea
• Sweetened beverages including juice, soda, sweetened tea, or energy drinks
• Diet sodas and artificial sweeteners – while calorie-free, these may trigger insulin responses in some people
• Alcohol – contains calories and affects metabolism
• Smoothies or protein shakes – contain significant calories and nutrients
• Milk alternatives like almond, oat, or soy milk (except in very small amounts)

How to Properly Break Your Fast

Breaking your fast correctly is just as important as maintaining it. Jumping straight into heavy, rich foods can cause digestive distress and diminish the benefits you’ve worked to achieve.

Start with Gentle, Easily Digestible Foods

When ending your fasting period, especially after longer fasts, introduce foods gradually to allow your digestive system to readjust. Your body has been in a rested state, and suddenly overwhelming it with heavy foods can lead to bloating, discomfort, and other digestive issues.

Foods particularly problematic for breaking a fast include:

• High-fat, greasy foods like fried items or fast food
• High-sugar foods including desserts and candy
• High-fiber raw vegetables, nuts, and seeds in large quantities
• Heavy, complex meals with multiple ingredients
• Carbonated or sugary beverages

Best Foods to Break Your Fast

Choose nutrient-dense, easily digestible options that provide energy without shocking your system:

Smoothies and Blended Foods: Smoothies made with fruits, vegetables, and protein sources are excellent for breaking a fast. Blending reduces fiber content and makes nutrients more accessible, easing digestion. Include ingredients like bananas, berries, leafy greens, and a protein source.

Dried Fruits: Dates, in particular, are traditionally used to break fasts in many cultures. They provide concentrated natural sugars for quick energy along with fiber and minerals. Other dried fruits like figs or apricots also work well in small portions.

Cooked Vegetables: Soft, cooked vegetables—especially starchy ones like sweet potatoes, squash, or regular potatoes—are gentle on your digestive system while providing important nutrients and fiber.

Soups and Broths: Light soups with vegetables, lentils, or small amounts of lean protein provide warmth and nutrients in an easily digestible form. Avoid cream-based soups or those with tough, fibrous vegetables initially.

Fermented Foods: Unsweetened yogurt, kefir, or small amounts of sauerkraut can help reintroduce beneficial bacteria to support digestion. Choose plain varieties without added sugars.

Healthy Fats: Avocados, eggs, or small portions of nuts can provide sustained energy and important nutrients. These are particularly good if you’re following a ketogenic approach to fasting.

Lean Proteins: Once you’ve reintroduced gentler foods, add lean proteins like chicken, fish, tofu, or eggs. These provide essential amino acids without being too heavy.

Portion Control When Breaking Your Fast

Start with smaller portions than you might typically eat. Your stomach may have reduced capacity during fasting, and overeating can cause discomfort. Listen to your body’s hunger and fullness cues.

After successfully tolerating your first post-fast meal, you can gradually return to your normal eating patterns, incorporating a balanced diet of whole grains, proteins, healthy fats, vegetables, and fruits.

Common Mistakes to Avoid During Fasting

Using Fasting as an Excuse for Poor Eating

Intermittent fasting isn’t a license to eat unlimited junk food during eating windows. The quality of your diet still matters significantly for overall health. Focus on whole, minimally processed foods rich in nutrients to maximize fasting benefits.

Overeating After Fasting

It’s natural to feel hungry after fasting, but binge eating during your eating window can negate the caloric deficit and metabolic benefits of fasting. Practice mindful eating and allow your body time to register fullness.

Not Staying Hydrated

Dehydration is a common issue during fasting. Ensure adequate water intake throughout your fasting period. Many people mistake thirst for hunger, so drinking water can also help manage appetite.

Fasting Too Aggressively

Extended fasting or very restrictive eating windows aren’t appropriate for everyone. If you’re new to fasting, start with shorter fasting periods and gradually extend them as your body adapts.

Different Types of Fasting and Their Rules

Understanding your specific fasting protocol helps determine what’s acceptable to consume:

Time-Restricted Eating: This involves eating within a specific window each day (like 16:8, meaning 16 hours fasting and 8 hours eating). During fasting hours, stick to zero-calorie beverages.

Alternate-Day Fasting: This alternates between regular eating days and fasting days. On fasting days, some protocols allow up to 500 calories, while others require complete fasting.

5:2 Diet: Eat normally for five days per week and restrict calories to 500-600 on two non-consecutive days. On restricted days, you can eat small, low-calorie meals.

Extended Fasting: Fasts lasting 24 hours or longer. These require careful planning and may benefit from electrolyte supplementation. Consult with a healthcare provider before attempting extended fasts.

Fat Fasting: Allows consumption of healthy fats during fasting periods to maintain ketosis while controlling hunger. This is less strict than other fasting types but still provides some benefits.

Who Should Be Careful with Fasting

While intermittent fasting can offer health benefits for many people, it’s not appropriate for everyone. Certain individuals should avoid fasting or only do so under medical supervision:

• Pregnant or breastfeeding women
• Children and teenagers
• People with a history of eating disorders
• Individuals with diabetes or blood sugar regulation issues
• Those with certain medical conditions
• People taking certain medications

If you have any health concerns or take medications, consult with your healthcare provider before starting any fasting regimen. They can help determine if fasting is safe for you and provide guidance on how to do it properly.

The Science Behind Fasting Benefits

Understanding why certain substances break a fast requires knowing what happens in your body during fasting:

Insulin Reduction: When you’re not eating, insulin levels drop, allowing your body to access stored fat for energy. Consuming foods that spike insulin interrupts this process.

Ketosis: After several hours of fasting, your body depletes glucose stores and begins producing ketones from fat for energy. This metabolic state offers various health benefits. Consuming carbohydrates or excessive protein can interrupt ketosis.

Autophagy: This cellular “housekeeping” process increases during fasting, helping your body break down and recycle damaged cellular components. Consuming amino acids, particularly leucine found in BCAAs, can inhibit autophagy.

Human Growth Hormone: Fasting can significantly increase HGH production, which aids fat burning and muscle preservation. Eating, particularly foods high in sugar, suppresses HGH release.

Research suggests intermittent fasting may support weight management, improve metabolic health markers, reduce inflammation, and potentially extend lifespan, though more long-term human studies are needed.

Practical Tips for Successful Fasting

Plan Your Fasting Schedule

Choose a fasting window that fits your lifestyle. Many people find it easier to fast overnight and skip breakfast, while others prefer eating earlier and fasting in the evening.

Stay Busy During Fasting Hours

Keeping your mind occupied helps manage hunger. Schedule activities, work, or hobbies during times when you typically feel hungriest.

Listen to Your Body

If you feel extremely unwell, dizzy, or weak during fasting, it’s okay to break your fast. Fasting should be challenging but not dangerous. Build up your tolerance gradually.

Prepare Your Break-Fast Meal in Advance

Having healthy, appropriate foods ready prevents the temptation to grab whatever’s convenient (and likely less healthy) when your eating window opens.

Consider Your Activity Level

Intense exercise may be challenging during fasting periods. Some people prefer lighter activities while fasting and save harder workouts for after eating.

Frequently Overlooked Factors That Can Break a Fast

Some less obvious items can interrupt your fasting state:

Chewing Gum: Even sugar-free gum can trigger digestive enzymes and insulin responses in some people. The artificial sweeteners may also affect your fast.

Flavored Water: Waters with natural or artificial flavoring may contain hidden calories or sweeteners. Stick to plain water to be safe.

Toothpaste: While the minimal amount of toothpaste you might swallow during brushing won’t significantly impact your fast, some people are sensitive to the sweeteners and prefer fasting-friendly tooth powders.

Medications: Some medications contain fillers, coatings, or are taken with food for proper absorption. Don’t skip prescribed medications, but consult your healthcare provider about timing them with your eating windows if possible.

Breath Mints and Lozenges: These typically contain sugar or artificial sweeteners and can break your fast.

Conclusion

Understanding what breaks a fast empowers you to make informed decisions about your fasting practice. While pure water, black coffee, and plain tea are unquestionably safe during fasting periods, many other foods, drinks, and supplements fall into gray areas depending on your specific fasting goals.

Remember that strict fasting means zero calories, but some modified fasting approaches allow minimal calories from specific sources while maintaining many fasting benefits. The key is consistency and finding an approach that works for your body and lifestyle.

When you’re ready to break your fast, do so thoughtfully with easily digestible, nutrient-dense foods. Avoid the temptation to overeat or choose foods high in sugar, unhealthy fats, or excessive fiber immediately after fasting.

Most importantly, fasting should support your overall health and wellness goals. If you have any concerns about whether fasting is appropriate for you or how to implement it safely, consult with a qualified healthcare provider who can provide personalized guidance based on your individual health status and needs.

Sources:

• National Center for Biotechnology Information – Physiology, Fasting
• Frontiers in Nutrition – Intermittent Fasting Research
• MDPI Nutrients – Metabolic Effects of Intermittent Fasting
• PMC – Autophagy and Fasting
• Nature – Intermittent Fasting and Health
• MDPI – History and Practice of Fasting
• PubMed – Branched-Chain Amino Acids and Insulin Response
• PMC – Supplements and Fasting