How to Avoid Protein Shake Diarrhea

📌 Overview and Key Takeaways

This is a Certified Nutrition Coach’s guide on how to avoid protein shake diarrhea.

Discover how to meet your protein needs without causing digestive issues.

Last Updated
Jul 21, 2026

Author and Medical Reviewer

Written by Jack, CNC

Jack is a National Academy of Sports Medicine Certified Nutrition Coach.

Disclaimer: This article is for general informational purposes only and is not a substitute for personalized medical advice. Consult a licensed healthcare professional before making changes to your diet.

Protein Shake Diarrhea

Can Protein Shakes Cause Diarrhea?

If you find yourself rushing to the bathroom after drinking a protein shake, you are not alone.

Many people experience what is commonly known as protein shake diarrhea.

This means loose and watery bowel movements shortly after consuming a protein shake.

While these symptoms typically go away after a few hours, some people have reported dealing with protein shake diarrhea for days.

The good news is that protein shake diarrhea is entirely avoidable.

Keep reading to learn how to pick a protein shake or powder that will not cause diarrhea.

How Do I Avoid Protein Shake Diarrhea?

First of all, it is important to note that if you have existing gut issues, what you eat might not be fully broken down and absorbed.

This could lead to or worsen side effects like diarrhea.

In most cases, however, protein shake diarrhea is caused by specific ingredients.

🚫 Avoid Food Additives

Ultra-processed food additives like emulsifiers and thickeners are hard to break down and absorb.

Ingredients like these can cause diarrhea because they increase the osmotic load in your intestines.

Osmotic load represents the total concentration of particles that draw water into the intestines.

Think of it like this: water naturally moves toward areas with more “stuff” dissolved in it, trying to balance things out.

As you might imagine, this can result in loose, watery stools.

⚠️ Here is a list of the most common food additives in protein shakes and powders:

• acacia fiber
• acacia gum
• acesulfame potassium
• artificial flavors
• ascorbic acid
• aspartame
• calcium carbonate
• carrageenan
• cellulose gum
• dextrin
• dicalcium phosphate
• dipotassium phosphate
• erythritol
• gellan gum
• guar gum
• gum arabic
• inulin
• locust bean gum
• maltitol
• maltodextrin
• mono- and diglycerides
• ‘natural’ flavors
• rice bran extract
• rice dextrin
• rice hulls
• rosemary extract
• silica
• silicon dioxide
• sodium alginate
• soluble corn fiber
• sorbitol
• soy lecithin
• sucralose
• sunflower lecithin
• tocopherols
• tricalcium phosphate
• xanthan gum
• xylitol
• zinc oxide

As a rule of thumb, if you cannot find it in nature or make it at home, it is probably a food additive.

🚫 Avoid Dairy-Based Proteins

Dairy-based proteins like whey and casein can also make you poop because they contain lactose – a sugar most adults cannot fully digest (Antonie Van Leeuwenhoek, 2026).

🚫 Avoid Artificial Sweetener and Sugar Alcohols

Artificial sweeteners and sugar alcohols resist digestion and can have a laxative effect (Eur J Clin Nutr, 2007).

Common artificial sweeteners include sucralose and acesulfame potassium.

Common sugar alcohols include erythritol and xylitol.

🚫 Avoid High Fiber

Insoluble fiber adds bulk to the stool, so if you eat a lot of it at once, it will make you poop.

High fiber protein shake or powder ingredients include chicory root, inulin, xanthan gum, and guar gum.

Believe it or not, many of these same ingredients are also used as laxatives (Br J Nutr, 1993)!

🚫 Avoid Protein Concentrates and Isolates

If you have a sensitive stomach, you might also want to avoid protein concentrates and isolates.

Most protein shakes and powders are made from one or both of these ultra-processed protein sources, which have been mechanically and/or chemically stripped of everything but the protein.

This includes the enzymes, fiber, and other natural digestive aids that help you break them down.

You therefore do not digest them in the same way that you do whole foods, which could affect your gut health.

For example, one study shows that regularly consuming protein concentrates and isolates might disrupt your gut microbiome (Nutrients, 2018).

Another study shows that it could cause the formation of toxic byproducts in your gut (Mol Nutr Food Res, 2024).

Although further research is needed, individuals with sensitive stomachs can play it safe by choosing protein shakes and powders made from minimally-processed protein sources like egg whites and almonds.

They are more gut-friendly.

Order Samples to see for yourself.

What Should I Do if I Have Protein Shake Diarrhea?

If you have diarrhea after drinking a protein shake, there are several steps you can take to manage it.

• Stay Hydrated: Diarrhea can lead to dehydration due to fluid loss, so drink plenty of clear fluids and avoid caffeinated and alcoholic beverages.
• Eat Bland Foods: Stick to bland, easily digestible foods such as bananas and rice. They can help firm up stools without irritating your stomach.
• Rest: Give your body time to recover by getting plenty of rest. Avoid strenuous activities that can further deplete your energy levels.
• Seek Medical Attention: If your diarrhea persists for more than a couple of days, you should consult a healthcare professional.

Finally, keep in mind that what triggers diarrhea for one person might not trigger it for someone else.

For this reason, you might want to consider working with a registered dietitian to identify the underlying cause and appropriate treatment.

Sources

1. Alimentary Pharmacology & Therapeutics (Aliment Pharmacol Ther). Review article: lactose intolerance in clinical practice–myths and realities. 2008.
2. European Journal of Clinical Nutrition (Eur J Clin Nutr). Gastrointestinal tolerance of erythritol and xylitol ingested in a liquid. 2007.
3. Antonie van Leeuwenhoek (Antonie Van Leeuwenhoek). Lactose intolerance and probiotics: from pathophysiological mechanisms to clinical applications. 2026.
4. Nutrients (Nutrients). Effect of a Protein Supplement on the Gut Microbiota of Endurance Athletes: A Randomized, Controlled, Double-Blind Pilot Study. 2018.
5. Molecular Nutrition & Food Research (Mol Nutr Food Res). In Vitro Fermentation of Animal and Plant Protein Isolates by the Human Gut Microbiota Under High and Low Carbohydrate Conditions. 2024.

Editorial Guidelines

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This article was written by a Certified Nutrition Coach and reviewed by a Registered Dietitian. We rely on peer-reviewed research and trusted medical sources, and regularly update our content to ensure accuracy and clarity.