Intermittent fasting involves only eating within a specific timeframe each day. So for most people on IF, that rules out a pre-workout snack before they start their exercise routine.

And some people do alternate day fasting, so they won’t have to worry about breaking their fasting period every day.

For many lifters, pre-workouts give them the extra boost of energy they need to power through their workouts. But, what if you are doing IF? Does pre-workout break a fast?

The short answer: it depends.

There's a little debate about how many calories would actually be enough to break your fast.

If you’re doing IF, whether or not your pre-workout breaks your fast depends on its ingredients.

Most pre-workout supplements have performance-enhancing ingredients that don't have any calories, so they won't break your fast.

If you've ever taken a serving of unflavored beta-alanine before a fasted workout, you know that the taste is downright awful.

So to take care of your taste buds, supplement companies use various sweeteners and flavors like sugar, sugar alcohols such as sorbitol, maltitol, xylitol, dextrose, and maltodextrin to make their pre-workout drinks more enjoyable.

Drinking these ingredients is where you’ll run into trouble if you’re fasting.

They often have just a few calories that raise your insulin levels, and they’ll break your fast when you consume them.

To be sure your pre-workout doesn’t break your fast, find one with little to no calories.

So does pre-workout spike insulin?

It depends. Your insulin response will also vary depending on your insulin sensitivity and other factors, and we’ll get more into that below.

does pre-workout break a fast

What Does Intermittent Fasting Do? (Benefits Explained)

To really answer the question, “does pre-workout break a fast,” we should understand what intermittent fasting does.

Intermittent fasting, or time-restricted feeding, is an eating pattern that cycles between periods of fasting and eating.

IF doesn't specify which foods you should or shouldn't eat to help with losing fat; it just tells you when you should eat them.

With IF, you have a fasting window where you don’t eat anything.

Once your body is finished processing and absorbing nutrients, insulin levels drop to a minimum (baseline) level, and your body enters a fasted or post-absorptive state.

When in a fasted state, the body switches on some fundamental processes required to maintain health and longevity.

That’s where the magic happens. When your body is in a fasting state, it uses fatty acids for energy.

People use Intermittent Fasting for fat loss, muscle growth, to improve their overall health, to simplify their lifestyles, and for many other benefits.

Research shows that intermittent fasting is a way to manage your weight and prevent — or even reverse — some forms of disease. [1]

Whether you struggle with high cholesterol, triglycerides, insulin resistance, inflammation and oxidative stress, or other metabolic and lipid dysfunction, fasting can help.

It may also help with cognitive performance and mental focus. Some even argue that long fasts improve our ability to access fat stores. It also changes hormone levels to facilitate weight loss.

In addition to lowering insulin and increasing human growth hormone levels, IF increases the release of the fat-burning hormone norepinephrine (noradrenaline).

Because of these changes in hormones, short-term fasting may increase your metabolic rate.

Intermitting fasting causes weight loss by changing both sides of the calorie equation by forcing you to eat less and burn more calories.

does pre-workout break your fast

Pre-Workout Ingredients That Won’t Break Your Fast


Caffeine is the primary source of energy in pre-workout.

The average amount of caffeine in pre-workout supplements can vary, but it typically ranges from moderate to high levels.

Caffeine boosts metabolism, improves strength, promotes muscle endurance, provides increased energy levels, and enhances anaerobic performance.

Fortunately, caffeine does not break a fast, so you can take a pre-workout with caffeine even if you are doing IF.

Caffeine may even increase the positive effects fasting has on brain function and inflammation. [2] 


Creatine is another popular additive to pre-workouts. It should also be safe to use while fasting.

Creatine doesn’t have the same benefits caffeine has for your fast, but it’s still calorie-free and won’t provoke an insulin response.

You can comfortably supplement with creatine without breaking your fast as mixing creatine with pre-workout can be an effective combination for enhancing strength, power, and overall workout performance.

Citrulline Malate

Citrulline Malate (a combo of L-citrulline and malic acid) is found in many pre-workouts, and it won't disrupt your fast either.

It works as a vasodilator, improving your blood flow by increasing nitric oxide levels.

Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness, and promotes muscle recovery.

With citrulline malate, your muscles get a better nutrient supply, so you get a better pump.


Beta-alanine helps build muscle mass by boosting carnosine levels. It is an amino acid found in meat, poultry, and fish.

The tingling effect you may feel after drinking a pre-workout supplement comes from this substance.

Beta-alanine is commonly used to improve athletic performance, build lean muscle mass in younger adults, and improve physical performance in elderly adults.

Consuming it won’t interfere with any intermittent fasting protocols.

Learn More - Why Does Pre-Workout Makes You Tingle?


L-theanine is great for Intermittent Fasting because it mitigates the negative effect of caffeine and reduces hunger.

L-theanine also reduces the stress that can be linked with fasting. And, it shouldn’t break your fast.

Alpha-glycerophosphocholine (Alpha-GPC)

Alpha-GPC increases acetylcholine levels, a neurotransmitter essential for learning and memory.

These supplements can also help improve exercise performance and increase growth hormone levels without breaking a fast.


Betaine is generally considered not to break a fast.

Betaine is involved in liver function and cellular reproduction and helps make carnitine. It also helps the body metabolize an amino acid called homocysteine.

Research shows that betaine may improve body composition, muscle size, and muscle power and force as it can increase creatine synthesis and elevates nitric oxide levels in the blood.

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Ingredients That Disrupt Fasting (Avoid These 3 Things)

Sugar, Artificial Sweeteners & Carbohydrates

There's a lot of debate surrounding the health benefits (or lack thereof) of artificial sweeteners.

Pre-workout brands add sugar, dextrose, sucralose, and other natural or artificial sweeteners with flavors to enhance the pre-workout's taste, texture, and color.

While the health benefits can be debated, sugar is also used to provide additional energy.

Some pre-workout powders use zero-calorie sweeteners, while others use regular table sugar.

Numerous studies have shown that any zero-calorie sweetener can cause an insulin spike, activating your digestion and breaking your fast.

Sugar also provides an immediate insulin spike in your blood, which kick starts your body's metabolism and takes you out of your fasted state.

Whey Protein

Pre-workouts that contain whey protein will also break your fast because whey protein contains calories.

You shouldn’t consume anything with more than 40 or 50 calories while intermittent fasting to avoid breaking it.

Amino Acids

Just about every pre-workout supplement contains one or several essential amino acids.

But, most branched chain amino acids contain a certain amount of calories, which will technically break your fast.

Proteinogenic amino acids and other amino acids are proven to spike your insulin level.

They activate protein synthesis pathways in your brain and signal that you've consumed food. So be mindful of the amino acids your pre-workout formula contains.

pre-workout break fast

What Pre-Workout Brands Affect Your Fast? (Compare Our Findings)

Here are a few pre-workouts popular in the health and fitness industry that won’t affect your fast. Most of them come in powder form.

  • Total War Pre-Workout: 
    Total War by Recon is an extremely popular pre-workout supplement. And the good news is that if you're fasting, its pre-workout blend doesn't have any of the three ingredients that will break your fast.
  • Alani Nu Pre-Workout: 
    This pre-workout has sucralose listed on the ingredient label. Sucralose could break your fast if you're fasting for health and weight loss.
  • C4 Pre-Workout: 
    C4 pre-workout formulas have zero calories, which in theory, makes it the perfect supplement to take during a fast. However, it does have CarnoSyn beta-alanine, a naturally occurring amino acid.
  • Ghost Pre-Workout: 
    Each 16.5-gram scoop of Ghost pre-workout contains five calories and a gram of carbohydrate. That will undoubtedly break your fast.
  • Lit Pre-Workout: 
    Lit pre-workout is gluten and sugar-free. However, it does have artificial flavors, sweeteners, and colors that could interfere with your fast.

Related Article - REDCON1 Total War Pre-Workout
Related Article - Beyond Raw Lit AF Pre-Workout
Related Article - Alani Nu Pre-Workout Review

does lit pre-workout break a fast

Safe Pre-Workout Alternatives When Intermittent Fasting


Coffee's main ingredient is caffeine, which is also the main ingredient in many pre-workout supplements.

Coffee can double as a natural pre-workout product. Black coffee is jam-packed with all the caffeine and antioxidants you need for your workout without the nasty natural flavors or additives, and it should also help with muscular endurance.

Many people opt to have their coffee black (to ensure there are no added calories) or as Keto Coffee.

Coffee itself shouldn’t break a fast. Just be careful if you add anything to it.

See Also - Pre-Workout Vs Coffee

Green Tea or Matcha

Tea is usually lower in caffeine than coffee, so it’s a great choice if you are sensitive to caffeine. But, like coffee, just remember not to sweeten it!

Sweeteners will break your fast, but you can also convert your tea into a Keto Tea.

Water (Still, Sparkling, Or Lemon!)

The one drink guaranteed not to break your fast is water. Although water doesn’t have the caffeine the other drinks have, it can still prepare you for your workout.

If you work out in the morning, a glass of water as soon as you wake up will help to energize your body.

You can also have sparkling water or add some lemon or Himalayan pink salt to it for an added kick.

Pre-Workout & Fasting FAQs

Is it safe to take pre-workouts when trying to lose weight?

It is safe to take a pre-workout if you’re trying to lose weight. The blend of ingredients in a pre-workout is meant to enhance your energy levels so you can work at a higher intensity during exercise, burning more calories during and after your workout.  

Properly fueling a workout can help you lose weight because having available glucose stores can prolong the intensity and duration of your workouts, which controls calorie burns.

Are there side effects to taking pre-workouts on an empty stomach?

Most pre-workouts are designed so they can be taken on an empty stomach. If you work out in a fasted state, you shouldn’t experience any issues or side effects. The pre-workout will just enter your bloodstream quicker.

That helps to maximize muscle pumps, the stimulatory effect, and helps you get going in the gym right away.

Do pre-workout supplements contain calories?

It depends on the brand of pre-workout you are using. Many pre-workout supplements contain artificial sweeteners or sugar alcohols.

These ingredients enhance flavor without adding calories, but some sweeteners may cause intestinal distress and discomfort or spike insulin levels.

Always check the ingredients list before taking a pre-workout supplement, and opt for pre-workouts with natural ingredients.

Should I still take my daily supplements when fasting?

Yes, you should be able to use most of your supplements while in a fasted state.

If your vitamins or medications upset your stomach or they need to be taken with food, just take them during your eating window. Experiment until you find what works for you and helps you thrive.

Can I use a fat burner while fasting?

You can take most fat burners while intermittent fasting as they shouldn't contain anything that can break your fast.


Everyone has different health and fitness goals. Whether you're losing fat, building muscle, or just want to look good in front of the mirror, you need to be sure you're doing things that help you accomplish your goals.

So, does pre-workout break a fast? It depends. But if you have recently started intermittent fasting but are worried you won't be able to take your pre-workout, don't be.

There are several pre-workouts you can take that won’t interfere with your fast. There are even natural alternatives, like coffee and green tea, that you can take instead of a pre-workout supplement that will have the same effects.

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Last Updated on August 21, 2023

Paul J

Paul J

Paul J is is an ex-professional footballer who has seen a gym or two and is an expert at knowing what is required for home gym setups. When he isn’t testing out products for his readers, he’s usually going for a run in the park or out for coffee.