Does C4 Break a Fast? (Supplement)

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 Intermittent fasting is beneficial for health and weight loss. But sometimes you may find yourself needing an extra boost of energy. Coffee and tea can’t get you very far, so you might start looking at various supplements. If you’re working out in your fasting window, pre-workout supplements may start looking appealing. They boost your energy and may even help you lose weight faster. One popular pre-workout supplement is C4. But does C4 break a fast?

If we look strictly at the caloric intake, one serving of C4 has no calories, which means it shouldn’t break a fast. The problem is that the ingredients may cause an insulin response, even if the caloric intake should technically be ok. So should you stay away from C4? Not necessarily.

Let’s take a closer look at how this supplement affects your fast, its benefits, and its side effects.


Does C4 break a fast?

The answer depends on your type of fast and your goals. According to the label, the C4 supplement has zero calories, which in theory, makes it the perfect supplement to take during a fast.

It contains 150 mg of caffeine, creatine, CarnoSyn beta-alanine, arginine, and several vitamins such as B6 or B12. Keep in mind some very strict fasting methods are against supplementation with vitamins during the fast. So if you’re following such a method, the C4 supplement can only be used during your eating window.

Most of the other ingredients shouldn’t be a problem under most fasts. The only exception is CarnoSyn beta-alanine, a naturally occurring amino acid. The problem with all types of amino acids is that they have been shown to occasionally cause an insulin response, which disrupts autophagy and takes you out of your fast. Most studies refer to BCAAs, so the effect of CarnoSyn beta-alanine alone might be less disruptive. However, if autophagy is your main goal, you may want to avoid supplementing with C4.

C4 also comes with several flavors that may contain artificial ingredients and sweeteners. While most of these are blood sugar-friendly, they have been linked to higher body weight as they can increase cravings.


Can C4 help your fast?

Yes, a pre-workout supplement like C4 can be beneficial. However, keep in mind that C4 is a pre-workout supplement, which is why most of its benefits are related solely to working out. So unless you plan on exercising after taking it, it might not be worth taking it. It isn’t a supplement created to help you get through your fast, its main goal is to energize you and help you build lean muscle through your workouts.



First of all, the vitamins will help you reach your daily values quicker. With intermittent fasting, getting all your vitamins and minerals from food alone can often be challenging, as you’re skipping 1-2 meals per day. Each of the other ingredients has its own specific benefits.



The caffeine will help boost energy, while the creatine and beta-alanine could help reduce your cravings. It will also help you reach better performance during your workout. 150 mg of caffeine is considered an average dose for a pre-workout. One cup of coffee has about 100 mg, so you won’t be overdoing it.


Creatine nitrate

Creatine is an essential supplement for any weight lifters. It helps you replenish your energy stores faster, so you can exercise more at a higher intensity. If you look at other similar supplements, you’ll see most of them have creatine monohydrate. C4 contains creatine nitrate, which is a newer version that’s supposed to be absorbed quicker by the body.



Arginine, specifically, Arginine Alpha-Ketoglutarate, in short, AAKG, helps you recover quickly after a workout and experience less soreness and stiffness. Sadly, C4 only contains 1 gram of AAKG, which is a small dose and its effect will be short-lived.


CarnoSyn beta-alanine

During any intense workout, lactic acid starts building up in your muscles. That leads to that feeling that your muscles are burning. Initially, that’s nice and tells you the exercise is working. After a while though, that feeling becomes uncomfortable and you’ll find yourself needing a break. CarnoSyn beta-alanine’s main role is to delay this acid burning feeling.

Like in the case of AAKG, the dose is very small, so don’t expect miracles.



The final notable ingredient, teacrine, is meant to boost and get you feeling motivated and alert. Unlike caffeine, teacrine is not a stimulant, so you don’t need to worry about feeling jittery after taking it.


Side effects

Some side effects include headaches, cramps, jitters, insomnia, or anxiety. These are side effects you risk with any pre-workout supplements. However, because the dosage of the ingredients is rarely low in C4, side effects are pretty rare

Stimulants are also not very well tolerated by everyone during a fast. C4 only gives you a little more than a cup’s dose of caffeine, but you may want to limit your intake outside the supplement. Classic fasts claim it is best to avoid hyper-stimulation during a fast, as the risk of insomnia, anxiety, and jitters will be higher. Of course, this varies from person to person. What is too much caffeine for a person, might be just perfect for you.


The bottom line

Does C4 break a fast? Looking at it purely from a calorie perspective, C4 doesn’t break a fast as it has zero calories. However, it does contain an amino acid, namely CarnoSyn beta-alanine. Amino acids have been shown to cause an insulin response in some people, which disrupts autophagy. In other words, if autophagy is your main goal, you should think twice about supplementing with C4.

Its benefits are mostly related to working out, so unless you plan on exercising, taking it may not be the best idea. The doses of the main ingredients are fairly small, which is why you shouldn’t experience any side effects. If things like jitters, insomnia, or anxiety happen, you may be consuming too much caffeine. Try lowering the dose and if it doesn’t help, rethink how and when you’re using C4.

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