Pre-workout is a category of supplements that contain a cocktail of ingredients that all serve different purposes to ultimately improve athletic performance. Because of this, there are a lot of questions that arise from consumers from “what are the ingredients?” to if it expires.
Fasting is a popular diet method to lose weight, manage blood glucose, improve cognition, and more.
It shouldn’t be combined with intense workouts, but if you choose to do so, here is some information to help you make informed choices. If you’re concerned with breaking a fast, some of these things may disrupt your fast, whereas others have no effect.
It also depends on the goal of your fast. Typically, people are fasting to either lose weight or enter ketosis to manage or prevent insulin resistance. Losing weight simply comes down to calories, whereas altering blood glucose with fasting is a bit more strict.
So in this way, it’s difficult to give a definitive answer as to whether pre-workout breaks a fast or not. It depends on the brand, and there are so many different pre-workouts to choose from.
Fasting seems simple because it simply means you can’t eat food and you can only drink single-ingredient, no-calorie beverages such as water (still or sparkling), coffee, and tea. However, when it comes to supplements, it gets a bit blurry. Some supplements are just a blend of vitamins and minerals, which have no calories. Others contain substances with caloric value like protein and sweeteners.
For those fasting to lose weight, a pre-workout supplement is not going to ruin your weight loss goals in most cases. Even if a fast is technically broken, those 15 calories will likely not be detrimental.
Table of Contents
Ingredients That Won’t Break Your Fast
As mentioned, some ingredients will and some will not disrupt your fasted state. When I mention a “disrupted fast”, it means that calories have been consumed and the body’s insulin is spiked. Insulin is the hormone released when blood sugar increases when we eat. You may or may not be aware that some substances spike blood sugar to a greater and faster extent than others.
Here is an ingredient breakdown of some of the most commonly included items in pre-workout blends:
Caffeine, Green Tea, or Matcha
Caffeine, in the form of black coffee or plain tea, doesn’t break a fast by itself. It’s typically the additions to these drinks that contain calories, like milk and sweeteners.
Creatine
Creatine is another common ingredient in pre-workout formulas that doesn’t break a fast. Creatine is an amino acid produced by the body that isn’t used to build proteins. Creapure® pH10 is a highly potent and bioavailable creatine form that more readily absorbs into muscle tissue to deliver its energy-enhancement benefits.
Citrulline Malate or L-citrulline
L-citrulline is an amino acid that produces L-arginine—a nitric oxide booster that enhances blood flow. Citrulline combined with malic acid is citrulline malate, which is supposedly a more easily absorbed form of L-citrulline.
Beta-Alanine
Beta-alanine is another non-essential amino acid that boosts nitric oxide production to improve blood flow. The only patented beta-alanine on the market backed by clinical research is CarnoSyn®, the go-to beta-alanine brand for pre-workout exercise performance enhancement.
L-theanine
This is another amino acid that isn’t used to make proteins. It is commonly associated with the main benefit of green tea. L-theanine is added to pre-workouts to minimize the negative effects potentially caused by caffeine.
Betaine
Sometimes labeled as betaine anhydrous, betaine is a nutrient added to pre-workouts to influence homocysteine levels. Since this compound is a nutrient, it won’t affect a fasted state.
Nootropics
Nootropics are substances that enhance cognitive functions like alertness, focus, and memory. They are sometimes used in place of caffeine in stim-free pre-workouts. Some examples found in pre-workout are Alpha-GPC, Rhodiola rosea, and ginkgo biloba.
Ingredients That May Break Your Fast
The pre-workout ingredients of most concern in terms of fasting are added sugars, artificial sugars, and proteinogenic (protein-building) amino acids.
Some Amino Acids
Branched-chain amino acids (BCAAs) is a class of essential amino acids that includes leucine, isoleucine, and valine. BCAAs are added to some pre-workouts to enhance muscle-building capacity and improve muscle soreness. They technically have some caloric value, but not too much.
Sweeteners
All of these helpful nutrients and compounds in pre-workout formulas don’t taste particularly good on their own, so companies add sweeteners, both natural and artificial, to make their products go down easier.
Artificial additives, sweeteners, preservatives, and thickening agents should be avoided to maximize your intermittent fasting results. Added sugars like glucose or dextrose are also included as a carbohydrate source in pre-workout for added energy.
Non-Calorie Sweeteners
Artificial sweeteners (for example, maltodextrin) may or may not affect fasting. Research is inconclusive as to the effect artificial sweeteners have on insulin and blood sugar regulation. This may seem confusing since no calories typically mean that something aligns with a fast. However, these artificial sweeteners do affect insulin resistance and interfere with the health of the gut microbiome. Because they potentially affect insulin, they will likely disrupt ketosis, or end an official fasting state.
Fasting Overview
Fasting is a broad term that covers the act of purposefully not consuming food. It is often associated with religion. In the case of fitness, we are generally talking about intermittent fasting.
Intermittent fasting has been tied to all sorts of health benefits ranging from improved energy to Alzheimer’s prevention. Consistent research shows that intermittent fasting has a positive effect on metabolic health. This likely comes down to the fact that when fasting, people are generally just eating fewer calories in a day since the time of eating is restricted to a smaller time frame. Regardless, if it improves health outcomes through healthy weight loss, it’s a viable technique to use.
There are various versions of an intermittent fasting regimen. An example of a daily approach is a 16/8 plan, which is to fast for 16 hours overnight and have an 8-hour feeding window during the day. Some people choose to fast for less than that and others for more. However, extremely long fasts (24-48 hours) provide no additional benefits and can be harmful to health.
The physiology of fasting is complex and can impact the body at a cellular level. This is why it’s important to discuss this with your doctor before starting a fasting regimen. The timing and structure depend on the goals of the fast.
A fasting diet is similar to a low-carbohydrate or ketogenic diet because if done correctly, both initiate ketosis. This is when the body has used all glycogen stores and must resort to burning fat as a secondary fuel source. The body can enter ketosis as soon as after 12 hours of fasting. Ketosis happens in the liver because this organ controls blood glucose. This mechanism is how fasting can, in some cases, contribute to diabetes prevention and changes in metabolism.
This leads to the idea of metabolic switching which is something that fasting advocates highlight. Metabolic switching is when glycogen stores are depleted and the body starts pulling from fat stores for energy.
Deciding what or what does not constitute breaking your fast will vary on an individual basis. It depends on your goals—whether you are trying to achieve ketosis, lose weight, or just improve your overall health.
Pre-Workout Overview
Pre-workouts are special supplements designed to stimulate workout-ready physiology for maximum performance and to build lean muscle mass. Most pre-workout supplements are made up of low or no-calorie compounds and nutrients.
Increased Energy and Focus
Caffeine, nootropics, and creatine are the attributes of pre-workout supplements that work to enhance energy and focus. Many fitness enthusiasts enjoy the extra alertness provided by pre-workout to keep them motivated and focused on their training.
Reduced Hunger and Cravings
Since many pre-workout supplements contain stimulants, this reduces the hunger and cravings of users.
Improved Athletic Performance
Few studies investigate the effect of multi-ingredient pre-workouts on athletic performance because the ingredients are variable, so it’s not very clean research. However, individual ingredients like caffeine, creatine, and beta-alanine have been proven beneficial for workout performance.
Why Pre-Workouts Might Be Good When Fasting?
It’s not recommended to work out in a fasted state. Most experts will recommend a pre-workout snack with carbohydrates and some protein to fuel you through your exercises.
However, if you do prefer to work out while fasting, pre-workout may be helpful. Firstly, it often contains caffeine, which acts as a stimulant and an appetite suppressant. Considering that individuals who haven’t been eating much may be low on energy, this may prove to be beneficial.
Also, the amino acids, creatine, and any other added nutrients are likely beneficial for someone who has been taking in limited nutrients.
What Can You Use Instead of Pre-Workout with Intermittent Fasting?
Coffee and tea are both typically fine to drink during an intermittent fast, and both will provide you with the caffeinated energy boost and mental focus similar to what’s in pre-workout. Of course, you won’t want to add any sweeteners, milk, or flavorings since these things all contain calories.
Green tea in particular has been tied to facilitating weight loss when combined with a healthy diet and regular exercise. Both coffee and green tea are considered thermogenic, meaning they act as internal heaters to help the body burn calories at a faster rate. So, for those who are fasting for weight loss, this may be an additional bonus.
Bottom Line: Does Pre-Workout Break a Fast?
Some ingredients in pre-workout may contain calories or trigger an insulin spike to break a fast and some will not. If you are concerned with maintaining a fasted state while taking pre-workout, ingredients to look out for are added sugars, artificial sweeteners, and amino acids—which include a few different individual aminos.
Importantly, try not to substitute pre-workout for eating actual foods. Adequate nutrition will always fuel your workouts just as well, if not more effectively, than dietary supplements. As always, work with a registered dietician or personal trainer to help you navigate the world of fasting and supplements.
FAQ
Can you have a pre-workout when fasting?
It depends on how strict the specific fast is, but most pre-workouts are low-calorie and will not trigger an insulin change. However, it depends on the brand of pre-workout as some may be 5-10 calories and others may be nearly 200 calories in a serving.
Does C4 pre-workout break intermittent fasting?
C4 pre-workout will not break a fast. It only has five calories and contains no additional sugar or calories.
Do creatine and pre-workout break a fast?
Creatine is a non-proteinogenic amino acid and will not break a fast. Pre-workout blends vary in ingredients, so some will break a fast and some will not.
Will five calories break a fast?
Technically, any amount of calories breaks a fast. However, five calories will not impact weight loss or ketosis.
How many calories are in pre-workout supplements?
This varies based on the ingredient list. Some pre-workouts may have 5-10 cals while others may have 200.
Is it okay to exercise while fasting?
It’s not recommended, but it is technically okay. However, without fuel, you may have to work out at a lower intensity.
Which ingredients in pre-workout break a fast?
The ingredients in pre-workout that can break a fast are added artificial sugars and some amino acids like BCAAs.
References
Anton, S. D., Moehl, K., Donahoo, W. T., Marosi, K., Lee, S. A., Mainous, A. G., Leeuwenburgh, C., & Mattson, M. P. (2018). Flipping the Metabolic Switch: Understanding and Applying the Health Benefits of Fasting. Obesity (Silver Spring, Md.), 26(2), 254–268. https://doi.org/10.1002/oby.22065
Longo, Valter D., & Mattson, Mark P. (2014). Fasting: Molecular Mechanisms and Clinical Applications. Cell Metabolism, 19(2), 181–192. https://doi.org/10.1016/j.cmet.2013.12.008
Mathur, K., Agrawal, R. K., Nagpure, S., & Deshpande, D. (2020). Effect of artificial sweeteners on insulin resistance among type-2 diabetes mellitus patients. Journal of Family Medicine and Primary Care, 9(1), 69–71. https://doi.org/10.4103/jfmpc.jfmpc_329_19
May, M. E., & Hill, J. O. (1990). The energy content of diets of variable amino acid composition. The American Journal of Clinical Nutrition, 52(5), 770–776. https://doi.org/10.1093/ajcn/52.5.770
Sanvictores, T., Casale, J., & Huecker, M. R. (2021). Physiology, Fasting. PubMed; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK534877/#:~:text=Most%20glycogen%20is%20stored%20in
Vasim, I., Majeed, C. N., & DeBoer, M. D. (2022). Intermittent fasting and metabolic health. Nutrients, 14(3), 631. https://doi.org/10.3390/nu14030631
