Do Protein Shakes Cause Constipation?

📌 Overview and Key Takeaways

Do protein shakes cause constipation?

Discover what causes protein shake constipation and how to avoid this common side effect.

Last Updated
Jan 7, 2026

Author and Medical Reviewer

Written by Kayla Kamen, MS, RD

Kayla Kamen is a Registered Dietitian with a MS in Nutrition.

Medically reviewed by Jennifer Fossett, PA-C

Jennifer Fossett is a Physician Assistant with a BA in Nutritional Sciences.

Protein Shake Constipation

Can Protein Shakes Cause Constipation?

Are you unable to poop after drinking a protein shake?

Although a common side effect of protein supplements is diarrhea, many people report that protein shakes and powders also cause constipation.

Constipation occurs when you have fewer than three bowel movements a week and your poop is hard and difficult to pass.

Common symptoms include bloating and stomach pain.

How Do I Relieve Protein Shake Constipation?

If you are constipated and looking for relief, try the following remedies:

1. Drink water – Drinking lots of water, especially warm or hot water in the morning, softens your stools.
2. Exercise – Movement can stimulate the muscles in your intestines.
3. Eat fiber – Fiber increases the size of your stool, helping it move through your digestive tract. It also softens your stool, making it easier to pass.
4. Drink coffee – Caffeine can stimulate involuntary muscle contractions in your colon.
5. Use a laxative – If all else fails, try a laxative. Most laxatives can be purchased over-the-counter. I put this on the list because laxatives have potential side effects, such as allergic reactions and vitamin deficiencies.

Keep in mind that everyone is different, so what works for you might not work for someone else.

Remember to be patient too, as most remedies take 12 to 72 hours to work.

Also note that occasional constipation is nothing to worry about.

If protein shakes regularly make you constipated, however, then it is time to switch brands.

You might consider a fiber-rich, plant-based option, like our Vegan Almond Protein Powders, which contains 5-8 grams of fiber per serving.

Dietary fiber, also known as roughage, is the indigestible part of plants.

Unlike other nutrients, it is not broken down and absorbed by the body.

Instead, it passes through the digestive tract relatively intact, speeding up digestion by adding bulk to the stool.

Why Do Protein Shakes Cause Constipation?

Unless you have a food allergy or sensitivity, protein shake constipation has nothing to do with the type or amount of protein in your protein shake.

Instead, protein shakes tend to cause constipation because they are made with ingredients that are hard to digest.

Before we get into what these ingredients are, however, it is worth mentioning that high protein intake, especially in the absence of carbohydrates and fiber, can cause your gut bacteria to ferment the protein.

Protein fermentation, in turn, increases the production of ammonia, branched-chain fatty acids, and other nitrogenous compounds, which might impair gut motility.

And impaired gut motility, which is the movement of food through your digestive tract, can contribute to altered bowel habits, including constipation.

To prevent this from happening, either choose a protein supplement with some carbs and fiber, or mix it with high fiber foods like fruits and veggies.

Now that you know not eat protein without any carbs and fiber, here are the top protein supplement ingredients known to cause constipation:

🚫 Avoid Food Additives

Emulsifiers, thickeners, and other additives look nothing like real food, making them hard to digest.

This means that they spend longer in your gut feeding your hungry gut bacteria, which produce gas as they eat.

And gas, specifically methane gas, slows colonic transit, or the amount of time it takes food to travel through the colon (Cureus, 2019).

Exactly why this happens is somewhat of a mystery, but researchers believe that intestinal gas may reduce intestinal motility (J Neurogastroenterol Motil, 2015).

Regardless, an excess of gas in your intestines can cause constipation.

⚠️ Here is a list of the most common food additives in protein supplements:

• 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, although not an issue for everyone, can cause digestive issues.

This is usually because they contain lactose, a sugar many individuals with sensitive stomachs cannot fully digest.

But you might be sensitive to dairy-based proteins even if you are not lactose intolerant.

This is particularly true for casein protein, which forms a gel-like substance in your stomach that slows down digestion.

🚫 Avoid Protein Concentrates and Isolates

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

Most protein supplements 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 your gut break them down.

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

Studies show that regularly eating protein concentrates and isolates might disrupt your gut microbiome and cause the formation of toxic byproducts in your gut (Nutrients, 2018; Mol Nutr Food Res, 2024).

Individuals with pre-existing digestive issues should thus look for protein supplements made from whole food protein sources like egg whites and almonds, which are easier to digest and absorb.

Order Samples to see for yourself.

Sources

1. Cureus (Cureus). Methane and Constipation-predominant Irritable Bowel Syndrome: Entwining Pillars of Emerging Neurogastroenterology. 2019.
2. Journal of Neurogastroenterology and Motility (J Neurogastroenterol Motil). Relevance of Colonic Gas Analysis and Transit Study in Patients With Chronic Constipation. 2015.
3. Nutrients (Nutrients). Effect of a Protein Supplement on the Gut Microbiota of Endurance Athletes: A Randomized, Controlled, Double-Blind Pilot Study. 2018.
4. 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 Registered Dietitian and reviewed by a Physician Assistant. We rely on peer-reviewed research and trusted medical sources, and regularly update our content to ensure accuracy and clarity.