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Home Fasting How Many Calories Break a Fast? The Science of Fasting

How Many Calories Break a Fast? The Science of Fasting

How many calories break a fast

Intermittent fasting has many rules when it comes to losing weight.

You can follow several variations depending on your weight loss goals. Some people avoid calories completely, while others try to stay below 50 calories during a fast. 

Cutting out food and beverages can be difficult in a fasted state. Your body wants that energy because it’s used to a normal diet. If you like the challenge and want to drop a few pounds, it’s worth learning about calories and fasting. 

Keep reading to discover how many calories break a fast and drinks that won’t ruin your intermittent fasting plan.

How Many Calories Break a Fast? Staying on Track

Technically, consuming just one calorie can break a fast. Your body only burns through fat stores when it doesn’t have any food or glycogen to burn. To lose weight quickly and safely, avoid calories completely until you reach the eating window again. 

Any amount of calories will slow the fat-burning state. This is because the body has been given fuel to work with, meaning it stops using fat for energy. Losing weight on an intermittent fasting method only happens when you cut out food and drinks correctly. 

Not everyone has to stick to the no-calorie rule on intermittent fasting. Some people could have 50 calories outside of the eating window. Their weight loss progress might be slower, but they will have more energy when it comes to exercising regularly. 

Overall, you should choose a fasting plan that works for your goals, but just remember that one calorie can bring you out of the fasted state quickly. 

Can you have any calories while fasting? 

Yes, but it highly depends on your personal fasting approach. If you are clean fasting, even one calorie will break your fast. People who are dirty fasting can consume up to 100 calories during their fasting windows to avoid hunger pangs. 

You are allowed to consume calories during intermittent fasting. There is nothing wrong with sticking to a very low-calorie diet during the fasted state. Dirty fasting is common for those who need the energy to exercise or can’t overcome hunger throughout the day. 

On the other hand, clean fasting can help you lose weight fast. A study found that intermittent fasting induces a strong fat-burning state when you don’t have calories. This is important for dropping body weight quickly and maintaining blood sugar levels. 

What Can I Have While Fasting?

You can still have certain foods and drinks with very few calories. Some options include bone broth, coconut oil, grass-fed butter, and apple cider vinegar. Just remember that calories can slow down fat burning while intermittent fasting. 

Bone broth is a common nutrient-dense drink consumed during the fasting window. This is because it contains few calories and a high amount of minerals. It’s believed that magnesium in bone broth can boost your metabolic rate over time. 

What Can I Have While Fasting


There are also healthy fats that could curb your appetite during a fast. You can add coconut oil, MCT oil, or grass-fed butter to your coffee. This beverage might help stop hunger pangs while giving you more energy during the fasting period. 

Apple cider vinegar offers health benefits like reduced blood sugar, better digestion, lower cholesterol, and a reduction in body weight. A study discovered that one tablespoon of ACV a day might help you drop 18% of body fat over 12 weeks. 

Can I Drink While Fasting?

Sure, you can drink during fasting, but it should ideally be water. Since water has no calories, it will not break a fast. If you want to maintain burning fat and fueling your body throughout the fasting phase, you must stay hydrated.

Can I Drink While Fasting

Some people like to drink diet soda and other calorie-free drinks as well. They believe these beverages won’t break a fast because they don’t contain calories. However, this is not true, as diet soda is made with artificial sweeteners and might contain caffeine and added flavorings. 

Research suggests that too many low or zero-calorie sodas can even increase the risk of heart disease and metabolic syndrome. 

You should always read nutritional labels before trying something on a fast. Diet soda can throw people off because it claims to have no calories. The same goes for sparkling water or energy drinks that use gellan gum and preservatives to maintain the taste. 

Just make a note of how many calories are in each beverage and stick to plain water if you want to boost your intermittent fasting progress. 

What can I drink while fasting? 

You can have water and black, unsweetened coffee or any unsweetened tea. Not adding sugar or milk to hot beverages ensures the calorie count is zero. However, the best practice is only to drink still or sparkling water while fasting.

Studies prove that drinking water can increase your energy expenditure. This refers to how many calories you need to sustain normal bodily functions. The more calories you burn throughout the day, the more stubborn fat you will lose with intermittent fasting.

Alternatively, you can have unsweetened black coffee or tea if you need that little boost of energy. Caffeine naturally strengthens your metabolism and digestive system. Always monitor your calorie intake while drinking beverages to avoid slowing weight loss. 

A Word From a Nutritionist

Clean fasting is the best way to lose weight in a safe amount of time. You have to avoid eating or drinking calories during the fasting window to burn fat efficiently. For those who get hunger pangs, consume plenty of healthy fats and vegetables before the fast. 

You can still gain similar health benefits if you drink black coffee, unsweetened tea, or bone broth. Since they are low in calories, they won’t contribute to weight gain. Just try to avoid products containing artificial sweeteners, milk, sugar, and preservatives. 

It’s also worth noting that chewing gum is not the best for fasting. A study found that gum stimulates your digestive system and tricks the body into thinking it’s hungry. You will then experience more hunger pangs when trying to finish the fasting period.


Consuming one calorie can technically break your fast. This is why you should stick to drinking water if you want intermittent fasting to be successful. For those who need some alternative fuel sources, consider having unsweetened black coffee or herbal tea.

Written by
Edibel Quintero, MD

Edibel Quintero is a medical doctor who graduated in 2013 from the University of Zulia and has been working in her profession since then. She specializes in obesity and nutrition, physical rehabilitation, sports massage and post-operative rehabilitation. Edibel's goal is to help people live healthier lives by educating them about food, exercise, mental wellness and other lifestyle choices that can improve their quality of life.

How many calories break a fast

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