Pre-Workout on Empty Stomach is Okay, But Not for Everyone

9 min read
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David J. Sautter post Reviewer
The article is verified by David J. Sautter
NASM Personal Trainer, NASM Fitness Nutrition Specialist, ACE Sports Conditioning Specialist, NASM Performance Enhancement Specialist, BA in Professional Writing

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The age-old supplement question: Should you drink a pre-workout on an empty stomach?

This depends on numerous factors, including age, medical history, and the overall health and resiliency of your stomach. 

While some people might have no issues with drinking pre-workout supplements on an empty stomach, this may not be the case for everyone. 

What’s more, some ingredients may have harsher side effects than others.

In this article, we discuss when pre-workouts should be paired with a meal and when they can be safely taken on their own on an empty stomach.

Benefits of Pre-Workout on an Empty Stomach

Some people may prefer taking ergogenic aids like pre-workouts on an empty stomach for one reason or another. 

Let’s first take a look at why some gym goers may opt to drink these energy-boosting supplements without food. 

Faster Absorption

You can take a pre-workout without eating if you need its active ingredients to act fast, as food would slow down its digestion and absorption process. 

Faster absorption means that caffeine and other active ingredients present in the pre-workout are metabolized rapidly, providing their ergogenic benefits without the delay that would normally accompany eating beforehand. [1]

Promotes Increased Fat Burning

Taking pre-workouts on an empty stomach has some benefits, particularly for people who aim to lose body fat. 

Exercising on an empty stomach can potentially support the muscular metabolic adaptations required to burn more lipids to produce energy.

The catch is that you must also consume amino acids to protect your hard-earned muscle mass from breaking down and being used as fuel during your fasted state. 

Eating no food before your session, especially after an overnight fast, may also mean you have lower energy levels, so pre-workouts can be a great way to give yourself that power boost without the need to eat extra calories. [2]

Most people eventually adjust to this once it becomes a habit, but it’s not a bad idea to give yourself a boost if you’re just starting to make this a habit.

Supports Energy Levels (When You Need Them Most)

As mentioned above, when you take pre-workouts on an empty stomach, their active ingredients enter the bloodstream rapidly and become available when you need them most during your workout.

Pre-workouts can therefore be useful for high-intensity intermittent exercises such as HIIT, CrossFit, and weightlifting as they will provide a quick energy source without the delay of digestion.

As we’ll discuss more below, if your goal is one that requires consistent calories in order to promote strength or muscle growth, you might want to skip fasted workouts, unless advised otherwise by a coach or doctor.

Side Effects of Taking a Pre-Workout in The Morning without Food

Having a pre-workout in the morning without breakfast on the side is usually fine, as these supplements have been designed and approved for consumption in both fed and unfed conditions, depending on one’s goals and needs

Yet, there might be some instances where this can actually cause some unpleasant side effects.

Risk of Hypoglycemia

Many people resort to consuming pre-workouts in the morning if they prefer getting into their workout sessions early in the day. 

However, having a pre-workout first thing in the morning on an empty stomach can lead to hypoglycemia if the training sessions are rather long and intense, as the body may not have adequate amounts of glucose circulating in the bloodstream. [3] 

Hypoglycemia is when blood glucose levels drop low enough to cause symptoms such as sweating, dizziness, nausea, and fatigue.

If pre-workouts are consumed on an empty stomach, and you’re doing long or intense bouts of exercise, your blood sugar may drop too low.

Jitters, Tingles, and Heart Palpitations

If a pre-workout contains stimulants, most notably caffeine, it can provoke some unpleasant side effects. 

Among them are jittering, shaking, tachycardia, and heart palpitations.

If you consume a pre-workout supplement on an empty stomach, you unintentionally increase this risk because there’s no buffer between the stimulants and the digestion process. [4] [5] [6]

Gastrointestinal Irritation

Some stimulant ingredients present in most pre-workouts, especially caffeine, can upset the gastrointestinal tract, specifically the small intestine, and lead to diarrhea or nausea. [6] 

Pre-workouts may also intensify the symptoms of irritable bowel syndrome (IBS), especially if daily caffeine consumption exceeds 400 mg. [7] [8] [9] [10]

Increased Blood Pressure

Taking pre-workouts first thing in the morning may not be ideal if you are particularly sensitive to caffeine or stimulants in general. 

These compounds may provoke acute increases in your blood pressure, which can be particularly alarming for those already suffering from hypertension.

If you have a history of issues with your blood pressure, heart health, or overall cardiovascular health, you should avoid pre-workout supplements until chatting with your doctor. [9] [11]

Pre-Workout Ingredients to Take on an Empty Stomach

All in all, you can take a pre-workout on an empty stomach, but if you want to avoid any of the side effects mentioned earlier, certain ergogenic ingredients give you a boost without making you feel sick. 

L-Theanine

L-theanine is an amino acid with great properties that can mitigate the side effects of stimulants to some extent. This ingredient is, in fact, able to aid relaxation and decrease blood pressure whilst also increasing mental alertness and concentration. [12] [13] [14]  

Supplementation of L-theanine with low doses of caffeine and tyrosine has also been shown to offer ergogenic effects in athletic settings. [15]

Caffeine (with L-Theanine)

An ingredient like caffeine may cause some unpleasant side effects; however, it was also shown to be the main ergogenic compound in multi-ingredient pre-workouts.

Caffeine consumption is a great way to enhance your energy levels as long as consumed within the recommended amounts.

With that said, if you want to take it on an empty stomach and you want to significantly reduce your risk of side effects, we suggest that you take it with L-theanine. [16]

Creatine

Creatine is one of the most widely used sports supplements thanks to its safety of consumption and extensive research backing up its beneficial effects on fitness performance. This is because creatine is optimal for increasing intramuscular creatine phosphate, a compound used for energy production during high-intensity activities. 

However, to be effective, creatine should be consumed daily, even on rest days, and not only when you need an energy boost. Also, it’s not required to do a loading phase of 20 grams per day for seven days if you plan on taking it consistently for the long term. [16] 

L-Citrulline

If you want a safe supplement to improve your fitness performance without side effects, then look no further. L-citrulline is a precursor of L-arginine, an amino acid able to synthesize nitric oxide, a compound able to increase blood flow, vasodilation, and mitochondrial respiration. [16] 

Research has shown that this non-essential amino acid can improve performance through these mechanisms without triggering gastrointestinal disorders or other side effects, even if consumed at higher doses. [17] [18]

When It’s Better to Pair Pre-Workouts with a Meal

Taking pre-workouts on an empty stomach is relatively safe as long as the recommended dosage is consumed. However, there might be some instances when it’s better to eat first, wait a bit for digestion, and then take a pre-workout supplement. Here are some of the main occasions when it’s better to pair a pre-workout with food.

Low Caffeine Tolerance

If you don’t have a good tolerance to caffeine, drinking highly caffeinated pre-workouts on an empty stomach can lead to some of the undesired side effects specified earlier. 

This is because food acts as a buffer and slows down the digestion of caffeine, enabling smaller and more regular doses of it to get into your bloodstream. [19]

Training to Increase Muscle Mass

Eating around your workouts is highly recommended if you are training to increase your lean mass, as your body not only requires energy to undertake the activity but also to prevent or minimize muscular catabolism. [20] [21

Eating exciting and tasty foods when trying to meet all your nutritional requirements can be difficult. However, you can use a workout app to discover plenty of delicious and healthy meals that would also provide you with all the nutrients you need to build muscle.

You Have Plenty of Time Before Your Training Session

If you have plenty of time between your pre-workout intake and training session, then having some food may help you increase the duration of its ergogenic effects as it slows down its digestion and absorption. [19] 

Though, having your pre-workout too early may result in its effects fading away by the time you get to the gym, so it is important that you get your timing right. 

Final Words

Pre-workouts are a very popular supplement, as they help get the extra energy they need to push harder in their workouts. 

Although they might occasionally come in with many side effects, especially if consumed on an empty stomach first thing after you wake up, it is not necessarily bad to take a pre-workout in the morning. 

Below you can find the main key messages about their efficacy and their side effects when consumed on an empty stomach:

  • Some people may choose to have a pre-workout on an empty stomach if they want it to act faster, or if they want to further aid fat loss.
  • Having a pre-workout without any food, especially first thing in the morning, may cause some side effects, such as hypoglycemia, jittering, shaking, nausea, and increased blood pressure.
  • If you want to benefit from the ergogenic aid of pre-workouts without risking getting any side effects, even when you haven’t had anything to eat, you can try L-theanine, caffeine, creatine, and L-citrulline instead. These ingredients have great ergogenic properties but a very low incidence of unpleasant reactions. 
  • Consume your pre-workout along with a meal if you have low caffeine tolerance, training to build muscle mass, or if you have plenty of time between your supplement consumption and your training session.
Disclaimer This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!



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