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What Not to Eat Before a Workout? (8 Foods You Should Avoid)

Tyler Sellers
Published by Tyler Sellers
Fact checked by Donald Christman, BHSc FACT CHECKED

I share pre-workout meal tips with my clients almost daily, but I also advise them on what not to eat before working out so they don’t sabotage their gym efforts.

I feel like I tried all possible meal combinations to improve my workout, and over the years, I definitely noticed some uncomfortable side effects.

So, I spent a few weeks researching and building upon my knowledge, and finally, I discussed the topic with a nutritionist to nail down which foods to avoid to get the most out of workouts.

Let’s dive in.

Quick Summary

  • Foods that cause irritation and acidity to the stomach, as well as dehydration of the body, should be avoided before starting a workout.
  • Staying away from the wrong foods can prevent you from experiencing adverse effects such as bloating and stomach cramps, which can decrease your ability to perform.
  • By avoiding snacks that can hurt your performance and eating pre-workout meals and supplements that work for your body, you can reach your fitness goals more quickly.

8 Foods You Shouldn't Take Before Exercising

Fiber foods top view

Let’s take a look at eight foods that proved to be detrimental to my clients, my colleagues, as well as my own training.

1. High-Fiber foods

Although fiber-rich foods are known to aid digestion, sports nutritionists don't recommend them before exercise.

This is because the indigestible sugar called raffinose, found in high-fiber foods such as Brussels sprouts, feeds the bad bacteria in your digestive system [1].

That causes your stomach to produce more gas, giving you gastrointestinal discomfort during your workout.

2. High-Fat foods

Traditional thinking sometimes suggests eating high-fat foods as one of the ways how to get energy before a workout.

However, research indicates that high-fat meals take longer to digest, which can delay energy release and weigh down on your performance [2].

Avoiding fried foods in favor of whole grains can provide you with quick energy to improve your training performance.

3. Spicy Foods

A bowl of spicy chilli pepper

According to research, the capsaicinoids found in chili peppers can help people work out more effectively [3].

There are, however, some individuals who experience heartburn and indigestion when they consume spicy foods.

Those who belong to this group may have difficulty completing their training routines.

4. Dairy Products

Nutritionists advise people (especially those with lactose intolerance) to avoid eating dairy products before working out because they contain fat and digest slowly.

Because blood flow to the stomach is reduced during physical activity, people feel bloated and gassy after consuming dairy [4].

To avoid feeling sick, you might opt for dairy-free products before exercising.

5. Carbonated Beverages

Carbonated drinks, such as sodas and seltzers, are discouraged by sports experts because they increase carbon dioxide in your gut, giving you an upset stomach.

This usually results in less fluid consumption, which might lead to dehydration [5].

Also, most fizzy drinks lack electrolytes and carbs, which are needed to fuel a hard workout.

6. Simple Carbohydrates

A woman drinking fruit juice

Simple carbs like candy, fruit juice, and table sugar can cause blood sugar crashes because they can only give you a short burst of energy [6].

They can help your muscle stores refill quickly, but they might not help you keep going for longer during your workout.

Complex carbs, like sweet potatoes, are your best bet for long-lasting energy to help you finish your training.

7. Energy Drinks

Most experts advise against drinking energy drinks due to their high sugar content.

They also say that consuming these drinks is one of the things you should never do before a workout because it can give you unnecessary calories.

Thus, preventing you from reaching your health and fitness goals.

Unlike a sports drink, an energy drink doesn't contain electrolytes, which can lead to dehydration and ineffectiveness during exercise [7].

8. Alcoholic Drinks

Alcohol, according to nutritionists, can slow you down by depressing your central nervous system (CNS). It also acts as a diuretic, making you pee more and leaving the body dehydrated [8].

In effect, your energy, strength, and agility may be compromised, impairing your overall workout performance.

Are There Other Benefits to Avoiding Certain Foods for Exercise?

A happy woman eating apple

There are many potential health benefits to avoiding certain foods, regardless of the initial reason for avoiding them.

Sugar, alcohol, and unhealthy beverages like energy drinks can cause inflammation and gastrointestinal distress, as well as contribute to diseases such as diabetes and hypertension.

"It's true that white foods like processed grains and sweets are higher on the glycemic index, quickly raise blood sugar and cause inflammation."

- Julia Zumpano, Registered Dietician

Also, avoiding highly acidic snacks on an empty stomach can help reduce your risk of serious GI tract problems, including acid reflux and metabolic syndrome.

Furthermore, keeping away from snacks that can increase your blood sugar levels and cause your blood pressure to fluctuate can help you live a healthier life in general.

What About the Drawbacks?

A person with an upset stomach

There can be some drawbacks to not eating particularly some of the best pre-workout snacks, such as missing out on vital nutrition that can help you build muscle or get healthier in general.

Avoiding healthy sources of fats, fiber snacks, dairy products, and spices, for example, can prevent you from getting additional micronutrients to help you get through your workout.

The key may be to take these foods at the right times, in other words, away from your workout, if you can tolerate them in general.

FAQs

What Is the Best Thing to Eat Before a Workout?

The best thing to eat before a workout is a snack that has carbs, protein, and healthy fats. This gives your muscles enough energy and prepares them to repair and produce new tissue fibers. Some foods with these nutrients include protein bars and a banana whey protein shake.

What You Shouldn't Do Before a Workout?

You shouldn't eat or drink excessively before beginning a workout. Overeating or “carb loading” can make you feel sluggish, while drinking too much can cause you to pee frequently and interfere with your motivation to exercise, ultimately preventing you from completing your training.

Top Foods to Avoid

So alcoholic beverages, as well as spicy, high-fat, and high-fiber meals, are probably not great before working out.

But since each person's body is different, there’s no one-size-fits-all approach here.

So, I always advise my clients first to take time to get to know their bodies and then start using safe and effective supplements like pre-workouts to fast-track their results.

These pre-workout supplements contain ingredients that are shown to work in clinical trials, and we've used them for years to help our clients lose weight, build muscle, and maintain good health.


References:

  1. https://time.com/85889/the-best-and-worst-foods-for-bloating/
  2. https://pubmed.ncbi.nlm.nih.gov/17823414/
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8778706/
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6316316/
  5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6195650/
  6. https://academic.oup.com/ajcn/article/78/4/843S/4690055
  7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2966367/
  8. https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/568848
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