Pre-Workout While Intermittent Fasting

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Pre-Workout While Intermittent Fasting

Intermittent fasting is one of the best ways to achieve your weight loss goals. Pair this with a regular workout then you have an excellent routine that will surely make you healthy and fit. Alongside a workout, pre-workout supplements are practically a staple with every fitness enthusiast.

If you have been wanting to try intermittent fasting and combine it with a good performing workout, then you may be curious how to manage both together. Especially since consuming a pre-workout before your exercise can help boost your performance.

But what if you workout during a fast and need to take a pre-workout supplement? Will it break your fast? Find out in this article about having a pre-workout while intermittent fasting and what you can do to make both work.

What Is A Pre-Workout?

Pre-workouts or pre-workout supplements are products intended to give you extra energy throughout your workout. The caffeine boost from the pre-workout supplementation helps you make the most of your gym time by giving you the energy to get there and the stamina to push through more extended exercises with more reps and intensity.

There are two types of pre-workout supplements: those that include stimulants and those that do not. The pre-workout powder is commonly purchased and combined with water to simulate the flavor of an athletic beverage.

It can, however, be ingested as food or as a tablet. Pre-workout, as the name implies, should be consumed before a workout performance. Although many individuals drink it during gym training or unfinished exercise, it should be finished at least 30 to 60 minutes before hitting the weights or cardio machines.

What Is Intermittent Fasting?

Intermittent fasting specifies the times when you eat your meals. You abstain from eating and drinking outside those times (besides water, teas, or non-caloric beverages). Fasting can deplete your body’s immediate energy stores (glucose).

After some time, your body runs out of glucose to burn for energy and resorts to burning your stored fat. Fasting may also improve your body’s ability to switch between fuel sources and work more efficiently, aiding in weight loss and muscle gain.

Fasting has been shown1 to help preserve lean muscle mass, which is essential if you want to reach your fitness goals. The greater amount of lean muscle tissue you have, the more calories you burn throughout the day, decreasing the likelihood of excessive fat accumulation and obesity2.

Many people find intermittent fasting safe, but it is not for everyone. If you’re pregnant or breastfeeding, skipping meals may not be the best way to manage your weight. Consult your doctor before beginning intermittent fasting if you have kidney stones, gastroesophageal reflux, diabetes, or other medical issues.

It’s worth noting that intermittent fasting can have unpleasant side effects, but they usually go away after some time. Possible side effects include:

  • Hunger
  • Fatigue
  • Insomnia
  • Nausea
  • Headaches

Types of Intermittent Fasting

The key benefits of fasting is its sustainability and that it can be easily incorporated into your daily life. As a general rule, you restrict eating into a 4–11 hour window, while the remaining 13–20 hours will be when you fast.

Essentially, you prolong your nighttime fast by delaying your first meal or stopping eating earlier in the day (or both). This type of fasting is usually done daily, but some people dip in and out of it, depending on their schedule.


The 16:8 is a popular form of intermittent fasting that is easy to implement daily. Simply put, you limit your eating to eight hours with 2-3 meals and fast for 16 hours.‍

For example, stop eating after dinner at 6 pm, prolong breakfast till 10 am the following day, eat for 8 hours, and the cycle begins again. You can change the timing according to your schedule—perhaps you prefer to eat earlier or later in the day.

This is the most recommended type of fast and generally what most people can handle.


The 20:4 diet is a time-restricted eating plan based on a 20-hour fast and a four-hour eating window.

You can generally eat to your heart’s content during the four-hour feasting period, but consuming too many calories in such a short period is difficult.

The four-hour eating window is usually in the evening, but it can be at any time of day that works for you. For example, you could eat two meals between 2 and 6 p.m. and then fast for the next 20 hours.

This is appropriate for those who are already comfortable with intermittent fasting, who work long days and don’t have time to eat, who don’t feel hungry during the day, or who find that eating makes them less productive.

Longer Fasts

Longer fasts are usually done every month rather than daily. These fasts are appropriate for those who are unable to commit to a daily fast but would like to incorporate it into their weekly, monthly, or yearly schedule.

If you already practice time-restricted eating, consider incorporating longer fasts throughout the year to boost ketosis.

5:2 / Fast Diet

The 5:2 or fast diet promotes fasting on two days per week. For any two days, calories are limited to 600 for men and 500 for women. Calories can be consumed in multiple meals throughout the day or all at once. This fast does not restrict eating for the next five days.

For example, you can typically eat throughout the week, except on Tuesday and Saturday, when you only consume 500-600 calories (2 meals of 250 calories or one meal of 500 calories) daily.

24 Hour Fast

The key is to fast for at least 24 hours between meals. For example, on day one, eat at 7 p.m. and fast until 7 p.m. the next day. Alternatively, you can eat earlier (for breakfast or lunch) and fast for 24 hours until the following day. You eat a meal every day but allow your body to fast for long periods. This type of fasting is typically done once or twice per week.

36 Hour Fast

This is a 24-hour fast that has been extended. On day one, you eat dinner, fast for the rest of the day, and then eat breakfast on day three. This type of fast can help jumpstart your ketosis transition or push you deeper into ketosis. This can be done as infrequently as once a week, month, or year.

Alternate Day Fasting

This involves fasting every other day, as the title indicates. Eating is limited to either one 500-calorie meal or complete fasting (without calories) on fasting days. You fast on one day and then eat what you want the next day. This is a strenuous method of fasting that is likely unsustainable in the long run.

Spontaneous Fasting / Skipping Meals

This one is recommended to anyone on the fence about intermittent fasting or feeling overwhelmed by the prospect of setting strict fasting times.

Your lifestyle and body may need to be guided by this gradual introduction to intermittent fasting. It is ideal for those who dislike feeling restricted or discouraged if they do not meet the requirements of their diet.

You allow yourself to skip meals if you are not hungry or too busy to eat. Meal skipping on rare occasions is an effective way to recondition the widespread belief that we need to eat three meals daily. You will not go hungry if you miss a meal now and then.

Fitness Benefits Of Intermittent Fasting

Intermittent fasting, combined with exercise, can have significant positive effects on your health and performance.

The list below are a few benefits of intermittent fasting to your fitness:

  • It increases growth hormone secretion with exercise.
  • Encourages reliance on fat metabolism with resistance training.
  • Better regulation of inflammatory response pathways.
  • Improved insulin sensitivity.
  • Enhanced neuroplasticity and cognitive health.
  • Combined with a nutritious, whole-food diet and exercise performance, may help keep your mind sharp and your body ready for high levels of everyday productivity.

Guide To Pre-Workout While Intermittent Fasting

The pre-workout supplement is taken before working out. A supplement is intended as a performance-enhancing substance taken just before working out and increase many aspects of exercise performance, such as:

  • Energy and Endurance
  • Strength and Stamina
  • Stress Resistance
  • Mental Focus and Intensity

Pre-workout supplements are specific supplements that encourage workout-ready physiology to maximize performance in both aerobic and anaerobic exercise activities.

Similarly, intermittent fasting is a dieting technique meant to boost your metabolic capabilities so that you may burn fat and muscle growth more efficiently, making intermittent fasting and pre-workout supplements a potentially synergistic combo as long as pre-workout vitamins do not interfere with the metabolic benefits of intermittent fasting, as many people worry.

Natural Pre-Workout Ingredients with Intermittent Fasting

A pre-workout supplement’s goal is to assist you in relaxing and recovering from a hard workout. Many pre-workout supplements commonly contain the following ingredients:


Pre-workout formulas can help you stay focused, provide energy, and increase your overall performance. High quantities of caffeine are the key element behind these promises.

Caffeine levels in pre-workout supplements range from 150 to 300 mg per serving. This is around three cups of coffee. If you are caffeine sensitive, you should take a lower amount or look for natural alternatives to enhance your energy before a workout.


This ingredient is meant to assist with high-intensity exercise. It may help to protect your muscles during heavy training. In sprinters, beta-alanine has been demonstrated to reduce fat oxidation and improve recovery.


This substance, when associated with exercise, helps develop strength. Creatine acts to refill your ATP levels, which provides energy for your muscles to contract. Creatine can also assist you in increasing your lean body mass.

Amino Acids

Pre-workout supplements contain branched-chain amino acids (BCAA) that aid in the growth of lean body mass. BCAA has also been linked to increased muscular development. It helps to minimize muscle damage after a good pre-workout.

Citrulline Malate

Citrulline malate is the amino acid L-citrulline bound with malic acid, which in the body converts to another amino acid known as L-arginine. It also promotes the production of nitric oxide (NO), which supports greater endurance, muscle force, power, and delays muscle fatigue.


L-theanine is an amino acid primarily found in tea and is responsible for some health benefits. It can offer an energy boost, improved mental health, and brain power. When paired with caffeine, l-theanine may further improve focus and attention as L-theanine can help to counteract the negative effects of caffeine, especially the jittery feelings and energy crash after it wears off.

Can You Take Pre-Workout on an Empty Stomach?

Yes, you can do a pre-workout on an empty stomach. When you take pre-workout supplements on an empty stomach, your body will digest them more quickly.

This means you can go to the gym shortly after taking the pre-workout supplement and still feel the effects.

Some people recommend eating before working out to avoid fatigue, while others believe working out on an empty stomach is beneficial. It is up to you to determine what works best for your fitness objectives.

Pre-workout on an empty stomach is unlikely to cause any side effects, but it is possible to experience a stomachache or headache.

Does Pre-Workout Break a Fast?

It all depends. First, it is determined by the reason for your fast. Pre-workout drinks will break your brief if you are fasting for religious reasons and must abstain from all food and beverages.

If you’re doing intermittent fasting, alternate-day fasting, or the 5:2 diet for health and fitness, the ingredients in your pre-workout will determine whether or not you break your fast.

Pre-workout supplement performance-enhancing ingredients generally do not contain calories and thus will not break your fast.

An exception to this rule is branched-chain amino acids, which contain calories and raise insulin response levels sufficiently to break a fast.

The problem is that they don’t always taste perfect—as anyone who has chugged a serving of unflavored supplement before will attest to.

To combat this, supplement companies add sweeteners and flavors like regular table sugar (and sugar alcohols like sorbitol, maltitol, and xylitol), dextrose, and maltodextrin to their products.

Many of these ingredients, however, contain calories that raise insulin levels when consumed. For example, sugar, maltodextrin, and amino acids raise insulin levels and thus break your fast.

As a result, if you want to make ensure your pre-workout doesn’t break your fast, a good rule of thumb is to consume those that are low or with no calories at all. Example, if your pre-workout supplement contains five calories per serving, that’s probably fine because it has almost no effect on insulin levels. However, if it includes 20, 40, or more calories, it will raise your insulin levels even higher, canceling some of the effects of fasting.

It’s worth noting that the only real benefit of intermittent fasting for fat loss is that it makes it easier for some people to control their calorie intake; thus, “breaking” your fast with a few calories from a pre-workout isn’t going to destroy your efforts as long as you remain in a calorie deficit.

Is it Okay to Workout While Fasting?

Exercising while fasting is generally safe to do. A fasted exercise or exercise can assist if you want to burn more fat in less time.

The principle behind fasting cardio is as follows: in the absence of readily available food fuel to convert to energy, the body resorts to stored fat for energy fuel. Thus, when you are in your fasting phase while exercising, you may burn your stored fat.

Fasted cardio has been validated by study3 as an effective and efficient fat-burning strategy.

Tips For Taking Pre-Workout Supplements

As with any supplement, see your doctor before a pre-workout blend, especially if you have any health issues or use medications. They will inform you whether or not these supplements are safe for you to consume.

If they give you the stamp of approval, a suggestion on how to use them is taking a pre-workout 20 minutes before you exercise. This allows the supplements to take effect. Remember to not take too much. Some side effects of pre-workout supplements can include: 

  • Digestive symptoms
  • Irregular heartbeat
  • The rise in blood pressure
  • Lower blood pressure
  • Changes in blood sugar

Stop working out immediately or taking the supplement altogether if you notice any symptoms that concern you. Confide with your doctor to prevent any more risk.


A pre-workout with intermittent fasting is an excellent technique for activating fat-burning processes and achieving your weight-loss goal.

Pre-workout supplements will break your fast if you are fasting for religious reasons and must abstain from all food and beverages. If you’re doing intermittent fasting, alternate-day fasting, or the 5:2 diet for health and fitness, the ingredients in your pre-workout will determine whether or not you break your fast. 

Pre-workout supplements are great for performance-enhancing and its ingredients generally do not contain calories. Thus will not damage your fasting streak.


1 Welton S, Minty R, O’Driscoll T, Willms H, Poirier D, Madden S, Kelly L. Intermittent fasting and weight loss: Systematic review. Can Fam Physician. 2020 Feb;66(2):117-125. PMID: 32060194; PMCID: PMC7021351.

2 Brady Susan, “5 Important Reasons to Maintain Lean Body Mass as You Age”, VTFC, October 25, 2022.

3 Aird TP, Davies RW, Carson BP. Effects of fasted vs fed-state exercise on performance and post-exercise metabolism: A systematic review and meta-analysis. Scand J Med Sci Sports. 2018 May;28(5):1476-1493. doi: 10.1111/sms.13054. Epub 2018 Feb 23. PMID: 29315892.


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