Does Pre-Workout Break a Fast

Would taking a pre-workout supplement be sabotaging your intermittent fasting? Taking a pre-workout can help boost energy levels while providing nutrients to elevate your results… but can this pre-workout break your fast?

Maximizing your workout by taking a pre-workout beforehand is a must for many people. But if the pre-workout is breaking your fast, it could ruin and derail the results you’ve worked so hard for. And it can be tough to find a straight answer from the internet if pre-workout breaks your fast or not.

The truth is that there are a few factors to consider when taking pre-workout supplements during your intermittent fasting window. While you can usually take a pre-workout when fasting, there are some brands and ingredients you need to check for first.

So, if you’re ready to discover how to successfully use a pre-workout supplement during your intermittent fasting period without breaking your fast, then keep going.

Can You Have a Pre-Workout When Fasting? Yes!

Unless you’re following a strict water-only fast, then there are quite a few pre-workout supplements you can take without breaking your fast.

Most pre-workout supplements only contain a tiny amount of calories, such as 5, 10, 15, or 20 total calories. They’ll usually use zero-calorie artificial sweeteners like sucralose, too. Pre-workout ingredients, such as caffeine and carnitine, will boost your intermittent fasting results.

For those following a more relaxed intermittent fasting routine, a “50-calorie rule” allows you to have a very small amount of calories during your fasting period without breaking your fast. This is especially true if you mainly follow an intermittent fasting diet for weight loss. This is known as “dirty fasting” or “lazy fasting.”

You’ll still get weight loss results and health benefits by taking a pre-workout during our intermittent fasting window. So, does pre-workout break a fast? Nope. Unless you’re doing pure water fast, there is more leeway with what you can have during your fasting window.

What Pre-Workout Won’t Break a Fast

scoop of pre workout and protein powder

First, if the pre-workout you’re taking contains sugar, it’s definitely not allowed during a fast. The goal of fasting is to keep your resting blood sugar and insulin levels as low as possible. Sugar will spike up your blood sugar and cause a big insulin response, which will for sure break your fast.

Many pre-workout supplements instead use zero-calorie artificial sweeteners such as sucralose, aspartame, stevia, monk fruit, etc. Since these artificial sweeteners do not contain any calories, then they shouldn’t break your fast.

But keep in mind that many fasting purists believe that your body could still have an insulin response from consuming these artificial sweeteners. Sucralose has zero calories but is 600 times sweeter than sugar, so your body could, in theory, still have an insulin response due to the high sweetness.1,2

If your body is used to taking artificial sweeteners, then your body will more likely adapt to the high sweetness of artificial sweeteners. If you’re not used to taking them, your body will likely have an insulin response. But you shouldn’t overdo it with sucralose since heavy chronic use could affect insulin and blood sugar.3

Supplements and vitamins that don’t contain any calories shouldn’t break your fast. They don’t contain any calories and no sugars, so they shouldn’t cancel out your intermittent fasting unless you’re doing a pure water fast.

But check the supplement facts label to see if the pre-workout supplement has added fillers such as dextrose or maltodextrin. These fillers could break your fat, especially in large amounts. But if it’s just a tiny amount (less than 50 calories), then you should be in the clear.

Best Pre-Workout for Intermittent Fasting

If you look at the back supplement facts label on pre-workout supplements, they contain a few calories. A pre-workout supplement might contain 5, 10, 15, or 20 calories due to calorie rounding laws.4

Suppose a pre-workout or energy drink has less than 5 calories. In that case, they can technically label it as containing zero calories. But if it’s 6 total calories, then they round it up to 10 calories. This tiny amount of calories can come from the vitamins, fillers, and preservatives in the pre-workout.

So, it’s best to find a pre-workout containing the smallest calories, no sugar, and no fillers. But as long as it contains less than 50 calories and you’re not consuming anything else during your fasting window, then you should be fine.

If the pre-workout contains BCAAs (branched-chain amino acids), it can cause an insulin response.5 But if your goal is to grow muscle and build lean muscle mass, then having some amino acids in your body can help. It’s best to take EAA (essential amino acids) instead of BCAAs since they contain all nine amino acids and provide a complete protein source.

If autophagy is your primary goal with intermittent fasting, remember that you should stick with a strict water-only fast. You can still get some of the autophagy benefits by doing a dirty fast, especially when combined with exercise. But still, you won’t get the same amount.

Now let’s break down some of the most popular pre-workout supplements to see if they’ll break a fast…

Alani Nu Pre-Workout

The popular Alani Nu pre-workout contains sodium citrate, silica, natural and artificial flavors, beet root powder, sucralose, and acesulfame potassium.

There are no calories listed on the supplement facts label. By FDA rules, supplements technically don’t have to list calories (zero or more) if there isn’t enough in measurable amounts. As long as the food or supplement contains less than 5 calories, then it can be listed as containing zero calories.

So, since Alani Nu’s pre-workout doesn’t contain calories or sugars, it won’t break your fast.

Cellucor C4 Pre-Workout

The Cellucore C4 pre-workout is listed on the supplement facts to contain citric acid, natural and artificial flavors, silicon dioxide, calcium silicate, malic acid, beet juice (color), sucralose, polydextrose, acesulfame potassium.

The supplement facts label says it contains zero calories, less than 1g of total carbohydrates, and zero sugars. So, by the rules, you can have a C4 pre-workout by Cellucor, and it won’t break your fast.

Bucked Up Pre-Workout

Bucked Up pre-workout supplements facts label says it contains natural flavors, calcium silicate, silicon dioxide, sucralose, beet root powder (for color).

The supplement facts label also says it does contain 5 calories per serving. So if you want to keep your calorie intake at zero while fasting, then you might want to find another pre-workout.

If you’re following the “50-calorie” fasting rule, then you should be fine with Bucked Up pre-workout, and it won’t break your fast. Due to calorie rounding laws they technically have to say it contains 5 calories even due to tiny derivative calories.

Gorilla Mode Pre-Workout

Gorilla Mode pre-workout supplement facts label says it contains natural flavors, calcium silicate, silicon dioxide, beet root powder (for color), sucralose, and acesulfame potassium.

The calories aren’t listed on the supplement facts label meaning it probably contains zero calories. Therefore, Gorilla Mode pre-workout shouldn’t break your fast.

Total War Pre-Workout

Total War pre-workout supplement facts ingredients include disodium phosphate, natural and artificial flavor, silicon dioxide, calcium silicate, sucralose, citric acid, acesulfame potassium.

There are no calories listed on the supplement facts label, therefore it shouldn’t contain any calories. Thus, Total War pre-workout won’t break your fast.

Ghost Pre-Workout

Ghost pre-workout supplement facts label ingredients include malic acid, citric acid, natural and artificial flavor, silicon dioxide, calcium silicate, tartaric acid, sucralose, beta-carotene (for color).

But Ghost pre-workout also says it contains 5 calories and less than 1g of carbohydrates. This is probably due to the flavoring. So if you’re really trying to keep your calories at zero when fasting, then you may want to look at another option.

Check out the Ghost pre-workout “Natty” flavor. It contains zero calories and uses stevia leaf extract as its sweetener. It’s a better option when fasting.

Beyond Raw Lit Pre-Workout

Lit pre-workout by Beyond Raw contains natural and artificial flavors, citric acid, tartaric acid, sucralose, acesulfame potassium, acetylated monoglycerides, calcium silicate, FD&C blue #1, FD&C yellow #5, glycerin, polysorbate 80, potassium sorbate, shellac, soy oil and lecithin blend, talc.

The supplement facts on Lit pre-workout says it contains 15 calories and 4g of carbohydrates. I wouldn’t use Lit pre-workout due to the calories, carbs, and other fillers and color dyes that are in it.

ProSupps Mr. Hyde Pre-Workout

Mr. Hyde pre-workout supplement facts label says it contains natural & artificial flavors, soluble dietary fiber, citric acid, malic acid, sucralose, silicon dioxide, calcium silicate, fruit and vegetable juice (for color), acesulfame potassium.

There aren’t any calories listed on the supplement facts, therefore Mr. Hyde pre-workout shouldn’t break your fast.

Alpha Lion SuperHuman Pre-Workout

Alpha Lion’s SuperHuman pre-workout supplement facts labels says it contains malic acid, silicon dioxide, natural & artificial flavors, sucralose, acesulfame potassium, FD&C red #40, FD&C blue #1.

There are no calories listed on the supplement facts label. Therefore, it should contain zero calories. So if it doesn’t contain any calories, then it shouldn’t break your fast.

Optimum Nutrition Gold Standard Pre-Workout

Optimum Nutrition’s Gold Standard pre-workout contains natural and artificial flavor, citric acid, calcium silicate, silicon dioxide, gum blend (cellulose gum, xanthan gum, carrageenan), sucralose, tartaric acid, malic acid, acesulfame potassium, red 40.

The supplement facts label says it contains 10 calories and 3 grams of carbohydrates. If you’re trying to keep calories and carbs to a minimum when fasting then you may want to look for another pre-workout, otherwise it could break your fast.


So, does pre-workout break a fast? Mostly not, especially if your main goal is weight loss. But you have to check the supplement facts label to make sure it doesn’t contain too many calories or ingredients that can break a fast.

If pre-workout doesn’t let you sleep at night, you’re probably taking it too late. Pre-workout supplements contain a high amount of caffeine (100-300 mg on average), which is more than enough to make you feel wired for hours.

It’s best to limit your caffeine intake to at least 8 hours before you plan to sleep. If you don’t have any adverse effects, you should be fine taking pre-workout every day. But I wouldn’t take it more than once per day.

I usually stick with just coffee or green tea when fasting. Add some C8-MCTs to boost energy levels, fat-burning, and brain power. It’ll also help you feel fuller for longer, making it easier to keep fasting for hours more.

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Now that you know you can have your pre-workout without it breaking your fast, be happy knowing you’re still getting the health benefits of fasting while being able to get your pre-workout, too.