One of the largest debates in the fitness community is whether or not you should take a pre-workout supplement on an empty stomach.

On one hand, there are benefits to taking pre-workout supplements on an empty stomach, but on the other, there are also concerns.

So, the best course of action would be to look at the evidence and see whether there's an actual answer to the question at hand.

You should take a pre-workout on an empty stomach if your goal is to enhance the absorption and the effects of active ingredients. However, taking a pre-workout on an empty stomach could lead to digestive system irritation and other pre-workout side effects.

The best option, should you choose to use pre-workout on an empty stomach, is to know what you can and cannot handle. Studying the ingredients, understanding your body, and the type of training you are about to perform is the only way to make an informed decision.

Can You Take Pre-Workout On An Empty Stomach? – GGP Guide

7 Gentle Pre-Workout Ingredients For Training On An Empty Stomach

Some ingredients are better for empty stomach exercise performance. Below we discuss the ingredients you should be on the lookout for.

1. L-Citrulline

Citrulline is a urea cycle amino acid that breaks down in the kidneys and is responsible for enhancing NO production and, with it, muscle endurance and pumps.[1]

If supplemented in dosages of 6 to 8 grams, L-citrulline should not cause any stomach discomfort.

2. Nitrosigine

Nitrosigine, a patented complex of bonded arginine and silicon, is responsible for boosting nitric oxide (NO) levels in the body, just like citrulline.

The recommended dosage is 1500 mg, which is well-tolerated and extremely unlikely to cause gastrointestinal distress.

3. Creatine

Creatine is a well-known and very potent ergogenic aid oftentimes found in pre-workout formulas. 

Despite the bed rep it sometimes gets, creatine is generally well-tolerated and does not typically cause stomach discomfort when consumed in recommended amounts of 3 to 5 grams daily.[2]

Related Article - Creatine Vs Pre-Workout 

4. MCT Oil (Medium-Chain Triglycerides)

Coconut oil derivative, medium-chain triglyceride (MCT), is a useful and popular ingredient for empty-stomach workouts.

While not commonly found in pre-workouts, MCTs are easily absorbed and fast-acting energy sources that will not aggravate the stomach unless taken in excess.[3]

5. HMB (Β-Hydroxy Β-Methylbutyrate)

Hydroxymethylbutyrate (HMB), a bioactive metabolite of leucine sometimes found in pre-workouts, is thought to improve muscle growth in certain individuals and is safe and easy on the stomach if taken in dosages lower than 3 g.[4]

6. L-Tyrosine

L-tyrosine is an amino acid that aids in the production of neurotransmitters, supporting cognitive function and stress response.

It's considered gentle on the stomach and can be taken in doses of 500 to 2000 mg without causing digestive discomfort, beneficial for mental focus during fasting workouts.

7. L-Theanine

L-Theanine, an amino acid found in green tea, promotes relaxation without drowsiness and can improve concentration.

In doses typically ranging from 100 to 200 mg, L-Theanine is virtually side-effect-free.[5]

Side Effects Of Taking Pre-Workout On An Empty Stomach

Before making the benefits a focus, the first thing to consider is to know what symptoms and issues you may encounter with taking pre-workouts in a fasted state.

Low Blood Sugar (Hypoglycemia)

When training fasted, especially after an overnight fast, your body's glycogen stores are lower. Since glycogen is the primary source of energy for most types of exercise, depleted levels can result in hypoglycemia or low blood sugar.

Hypoglycemia causes symptoms like dizziness, lightheadedness, shakiness, and even fainting, but this is more likely to happen if the exercise is moderate to high intensity or extends over a long period,

Thankfully, the hypoglycemia symptoms can be easily resolved by having a snack or small meal. While this goes against training your body in a fasted state, it may be necessary for those with blood sugar issues.

Digestive Problems

One of the most common side effects of fasted training and taking pre-workouts on an empty stomach is a variety of digestive issues.

As the stomach lining isn’t as robust when the stomach is empty, pre-workout ingredients, such as caffeine, may cause: 

  • Nausea
  • Heartburn and Acid Reflux
  • Stomach Pain
  • Diarrhea

Jitters and Anxiety

High caffeine dosages found in pre-workouts can cause pre-workout jitters, especially when taken on an empty stomach.

In more severe cases, jitters can even graduate into anxiety, followed by several anxiety-related side effects, such as trembling, difficulty breathing, skin itchiness (similar to beta-alanine itch), sweating, and elevated heart rate.


Another side effect that is often reported is dizziness or loss of balance. This can be the most dangerous side effect based on when it happens to you.

For example, if you are in mid-set, you can stumble, fall, or drop weights and injure yourself.

While it is difficult to pinpoint a specific cause of dizziness, it is usually due to lowered blood pressure or low blood sugar levels.[6]

man dizzy after taking pre-workout

My Experience Taking These Pre-Workouts First Thing In The Morning

I have taken the following pre-workout supplements on an empty stomach every other morning for two weeks. Here is what happened.

1. Woke AF Pre-Workout

With Woke AF, the main thing I noticed was an incredible increase in my energy levels whenever I'd take it first thing in the morning. To be fair, beta-alanine tingles were also very noticeable, but those had nothing to do with my fasted state.

As for stomach issues, some very mild discomfort was present early on, but it wouldn't affect my mood or athletic performance.

The biggest difference compared to when I would take Woke AF after a meal in the afternoon was the crashing. I'd feel quite depleted and fatigued around 2-3 p.m. whenever I'd take Woke AF early on and before breakfast.

Related Article - Woke AF Pre-Workout Review 

2. Transparent Labs BULK Pre-Workout

Transparent Labs BULK pre-workout is my go-to pre-workout whenever I'm hitting the gym early on.

Its potent formula is very mild on the stomach and has never given me any stomach issues whatsoever regardless of whether I had breakfast or not. It does give me the tingles from beta-alanine, but those are short-lived.

The main reason why I love BULK pre-workout in the morning is because its caffeine dose isn't high enough to disturb my empty stomach or, more importantly, cause crashes later during the day.

3. C4 Pre-Workout

I generally avoid all C4 products except for C4 Ultimate, but for the sake of research, I tried C4 Original.

C4 Original didn't cause any issues for me whatsoever. No stomach ache, no crashing, nothing. But, then again, my performance gain was not that significant.

In contrast to taking C4 after lunch, I'd say the biggest difference is onset time and potency. Since C4 Original isn't very powerful, it helps to take it on an empty stomach, as it will hit you a bit faster and a bit stronger.

Related Article - Cellucor C4 Pre-Workout Review 

recommended pre-workout!

Cellucor C4 Ultimate Pre Workout







Overall Rating


What To Avoid When Looking For A Pre-Workout?

There are dozens of pre-workout ingredients you should avoid, some because they're ineffective and some because they may be potentially harmful beyond causing you stomach issues or anxiety.

In terms of protecting your empty stomach and mitigating GI distress and other side effects, you should avoid high dosages of caffeine and other stimulants.

On a more general note, you should avoid:

  • Artificial Colors
  • Artificial Sweeteners
  • Proprietary Blends

Artificial colors, such as Red No. 40, Blue No. 1, or Red. No. 3 can be detrimental to your overall health. Some studies link these artificial colors to carcinogens with nasty side effects and even cancer in animals (Red. No. 3). [7]

Artificial sweeteners can potentially cause stomach issues. For instance, acute and chronic use of artificial sweeteners such as saccharin and sucralose is known to disrupt gut microbiota, potentially leading to various gut complications.[8]

You also need to avoid proprietary blend formulas. Technically, proprietary blends are implemented to "protect" the actual formulation from being reused, but in reality, it is just a simple way to cover up inadequate dosing of active ingredients. 

Artificial Additives & Sneaky Synthetics

Taking Pre-Workout On An Empty Stomach FAQs

Does working out on an empty stomach burn more calories?

No, working out on an empty stomach does not burn more calories. However, research tells us that your body is more likely to burn stored fat during fasted training.

What is the best pre-workout for fasted training?

The best pre-workout formula for fasted training would be any with approximately 200 mg of caffeine and between 6000-8000 mg of citrulline. That said, one of the best pre-workouts for fasted training, in my opinion, is the Transparent Labs BULK pre-workout.

What should you eat after having pre-workout?

The best thing to eat after taking a pre-workout and finishing your training session is a well-balanced meal with enough protein, carbs, and fats to facilitate muscle growth and replenish energy.

What are the best supplements to stack with pre-workouts?

There is no definitive answer to which supplement is the best stacked with pre-workouts, but creatine monohydrate could be a very good choice.


To sum up, you absolutely can take a pre-workout on an empty stomach. As long as you're mindful of the dosing, you shouldn't experience any issues and the pre-workout won't break a fast (not including religious).

In fact, well-designed and well-dosed pre-workouts can fuel fasting workouts. They can get you motivated, pumped, and focused, and most importantly, they will temporarily make up for any energy deficit you might be feeling due to a fasted state.





Last Updated on November 7, 2023

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Andrew White

Andrew White is the co-founder of Garage Gym Pro. As an expert fitness professional (gym building nerd) with over 10 years of industry experience, he enjoys writing about everything there is to do with modern fitness & the newest market innovations for garage gyms. When he isn’t testing out products for his readers, he’s usually out surfing or playing basketball.