Ever reach for an energy drink during your intermittent fasting period only to wonder if it’ll break your fast?
Energy drinks have become a popular alternative to coffee and other caffeinated beverages like tea in the morning. Imagine being able to freely have an energy drink during your fasting window, confidently knowing that it won’t break your fast.
But there are pros and cons to having energy drinks during your fasting window. And you’ll need to know which energy drinks are the best when fasting to make sure it doesn’t derail your results.
Here you’ll discover how energy drinks could possibly break or not break your fast. So keep reading if you want to know how to have an energy drink without it breaking your fast.
Can You Drink Energy Drinks While Intermittent Fasting
Quick Answer: You can have a sugar-free, zero-calorie energy drink during your intermittent fasting window without it breaking your fast unless you’re having a pure strict water fast.
During a pure water fast, you’re only allowed to have strictly water. Even black coffee or unsweetened teas won’t be allowed during a pure water fast. While this will maximize all the benefits of fasting, it is optional if your main goal is weight loss.
Dirty fasting, aka lazy fasting, is a more flexible approach to intermittent fasting where you can have certain beverages during your fasting period without breaking your fast. This makes it easier to keep fasting by curbing hunger and accelerating your results.
A “50-calorie rule” allows less than 50 calories during your fasting period and won’t significantly disrupt your metabolic state from fasting. This small number of calories will still allow you to lose weight by shifting your body into a fat-burning mode.
Does Caffeine Ruin Fasting?
Caffeine is a primary component of many energy drinks. It is the primary reason behind their ability to boost energy levels. Caffeine contains no calories, so it won’t break your fast. It can even benefit your results by enhancing your fat-burning.
Caffeine can suppress appetite, increase metabolism, and improve mood and focus.1,2,3 Studies find caffeine can stimulate lipolysis (the breakdown of fat) and thermogenesis (heat generated by the body).4 Both of these contribute to weight and fat loss.
Do Sugar-Free, Zero-Calorie Energy Drinks Break a Fast
Drinks allowed during intermittent fasting will contain minimal calories (less than 50) and don’t contain sugar. Sugar will break your fast since it contains calories and causes an insulin response.
But sugar-free, zero-calorie energy drinks will usually use an artificial sweetener like sucralose instead. Sucralose is a zero-calorie artificial sweetener (also found in Splenda), and there is some controversy about whether it can break your fast.
There is evidence and belief that artificial sweeteners like sucralose can cause an insulin release due to their high sweetness.5 Sucralose is 600x sweeter than sugar and could possibly trick your body into thinking sugar is being consumed.
In theory, this could trigger an insulin release since your body will want to prepare itself for the high sugar it thinks will be consumed. Scientists call it the “cephalic phase insulin release.” But there is mixed evidence that proves this. A lot will also depend on the person and their individual response to these sweeteners like sucralose.
So sugar-free, zero-calorie energy drinks shouldn’t break your fast. Even more so since they do not contain any calories. But you still have to consider that the high sweetness from the artificial sweeteners could trigger an insulin release which would break your fast.
Will a 10-Calorie Energy Drink Break Your Fast
If you’re following a more flexible “dirty fast” that allows up to 50 calories, then having a 10-calorie energy drink won’t break your fast.
Technically the FDA (U.S. Food and Drug Administration) allows a product to be labeled as having zero calories if it contains less than 5 calories per serving. So some of these zero-calorie energy drinks could contain up to 5 calories but can still be labeled as having zero calories.
The serving size on the nutrition facts label for the energy drink could also contain multiple servings. It might say it contains zero calories per serving, but the beverage could have multiple servings. This will allow them to technically label it as zero calories. Still, if they listed it as a 1 serving, these calories could surpass 5 calories, and they could have to list it as 10.
So be sure to check the nutrition facts label on the zero-calorie energy drinks to make sure they’re not trying to pull this trick. This is why many energy drinks say it contains 10 calories in the whole can. Zero-calorie energy drinks might contain less than 5 calories per serving, but more than one serving per can could add up to 10 calories too.
But with that said, even a 10-calorie energy drink shouldn’t break your fast. Like with zero-calorie energy drinks, your body could release insulin due to the high sweetness of the artificial sweetener despite it having zero calories.
There is mixed evidence for this, and you should still be able to lose weight with intermittent fasting despite these 10-15 calories consumed during your fasting window.
Benefits of Having Energy Drinks During a Fast
Having an energy drink during your fasting window can have some benefits.
Energy Boost: The caffeine in energy drinks is usually at least 200mg. This is more than enough to give you an energy boost during your fasting period. Fasting can be challenging, and you may feel your energy levels dipping since you won’t be eating foods like carbohydrates that give you fuel.
Curb Hunger: Caffeine is a natural appetite suppressant, so it should make it easier to get through your fasting window by curbing hunger. Hunger is the most challenging part of intermittent fasting, so the better you can curb it, the easier it’ll be.
Fat-Burning: The caffeine found in energy drinks has been found to stimulate lipolysis and thermogenesis. Lipolysis is the breakdown of fat, and thermogenesis is the heat generated by the body. Both of these are beneficial for weight loss and fat loss.
Increased Focused: The caffeine and additional ingredients in energy drinks can increase focus, alertness, and concentration. Caffeine stimulates the central nervous system helping you stay awake and alert for longer.
Enhanced Physical Performance: Ingredients in energy drinks like taurine, guarana, and B vitamins can all boost physical performance. Caffeine, too, can improve physical performance in sports, exercise, and activities. If you work out in the morning when fasting, an energy drink can elevate your performance.
Energy Drinks That Won’t Break a Fast
Here is a breakdown of some of the most popular energy drinks that won’t break your fast.
Monster Zero Ultra: Monster Zero Ultra energy drinks contain 10 calories and no sugar or carbohydrates, so they won’t technically break your fast. Like all energy drinks containing zero sugar or calories, it contains artificial sweeteners. It is a theory that artificial sweeteners are so sweet that they could cause an insulin release in your body, reducing fasting results. But make sure you find a Monster energy drink that doesn’t contain sugar if you are going to drink one during your fasting period.
5-Hour Energy: 5-hour energy shots contain a tiny amount of calories (4 calories), so they shouldn’t break your fast. 5-Hour Energy also doesn’t contain sugar or carbohydrates, which will also not contribute to breaking your fast. But 5-Hour Energy shots contain artificial sweeteners, which could cause an insulin release.
Red Bull Zero: Red Bull Zero contains 10 cal, is sugar-free, and won’t technically break your fast. Red Bull Zero contains artificial sweeteners aspartame and Acesulfame-K, which could also trigger an insulin response. Just make sure you get Red Bull Zero and not the standard Red Bulls since those contain sugar.
Bang: Bang energy drinks are listed as containing zero calories and zero grams of sugar or carbohydrates. With nutrition labeling, products can be labeled as zero calories if they contain less than 5 calories. Bang uses sucralose as an artificial sweetener which could lower your results from fasting.
Celsius: Celsius energy drinks have 10 calories and 2g of carbohydrates. While it’s advised to avoid having any carbs during your fasting period, that is a tiny amount that probably won’t ruin your results if you’re doing dirty fasting. Celsius uses sucralose as its artificial sweetener.
C4: C4 energy drinks are listed as containing zero calories and zero grams of sugar or carbohydrates. C4 uses sucralose and Acesulfame-K as its artificial sweeteners. So C4 energy drinks shouldn’t break your fast.
So do energy drinks break a fast?
The bottom line is zero calorie and sugar-free energy drinks shouldn’t break your fast as long as you’re not following a pure and strict water fast. A form of dirty fasting allows a “50-calorie rule” that gives you some leeway during your fasting window without breaking your fast. Energy drinks that don’t contain sugar fall into this category and won’t break your fast.
There are benefits to taking energy drinks during your fasting window, too. Energy drinks can provide higher energy levels, improve focus and attention, better physical performance, and curb hunger. One of the hardest parts of fasting is hunger, so the better you can stop this hunger from happening, the easier it’ll be to get through your fasting window.
Energy drinks do contain artificial sweeteners that some believe can cause an insulin release because they are so sweet. An instant release could break your fast or, on the lower end, reduce some of your results. But your body could also adapt and not release insulin the more you get used to fasting and having energy drinks during your fast. The more metabolically flexible you are then the less likely this will happen.
I personally rarely drink energy drinks when I’m fasting or not. If you have them once in a while, isn’t a big deal. There are studies finding long-term chronic use can raise insulin levels and cause gut issues.6,7 I prefer coffee mixed with C8-MCTs in the morning instead when I’m fasting to trigger a “metabolic switch” to burn more fat.
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With that said, if having a zero-calorie and sugar-free energy drink during your fasting window makes it easier to get through your fast, then you’re better off having one than not. Fasting can be challenging to hunger, so the better you can curb hunger by having an energy drink. You are more likely to fast for longer and stick with it. This will result in more benefits in the long run by falling, appearing strict water fast, and falling off the wagon too quickly.
Josh holds a Bachelor’s degree in Exercise Physiology and Nutrition Science. He’s a Certified Strength and Conditioning Specialist (CSCS) by the National Strength and Conditioning Association and he’s a Certified Personal Trainer (CPT) by American Council on Exercise. He’s worked as a Strength and Conditioning Coach at the high school and college levels. He has over 15 years of experience as a personal trainer and nutrition coach. He is also the author of The Flat Belly Formula. He strives to bring inspiration and results for people to live healthier lives through smart diet and exercise.