Does Protein Powder Make You Poop?

📌 Overview and Key Takeaways

Does protein powder make you poop?

This is a Dietitian’s guide on how to supplement your protein intake without upsetting your stomach.

Last Updated
Jan 6, 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 Powder Poops

Can Protein Powder Make You Poop?

Yes, protein powder can make you poop.

Although some people tolerate protein shakes and powders without any issues, others report changes in their bowel movements after adding protein supplements to their diet.

There are several reasons why protein powder can make you run to the bathroom.

For starters, high protein foods may stimulate bowel movements due to the fact that they trigger the release of hormones like gastrin and cholecystokinin (Front Endocrinol (Lausanne), 2020).

These two peptides are known to play important roles in digestive processes including gastric acid secretion and gut motility.

Certain types of protein, like whey protein, are also absorbed really quickly.

This may result in decreased colonic transit time, which can lead to diarrhea or more frequent bowel movements.

That said, neither of these reasons really explain why some protein powders make you poop, and others do not.

To make sense of it all, you have to take a close look at the ingredients.

Why Does Protein Powder Make You Poop?

I myself used to wonder, “Why does protein powder make me poop?”

It never made any sense to me, that is, until I realized what is in most protein powders.

It turns out most protein powders make me poop because they are full of added junk.

The second I switched to protein powder with a short list of simple ingredients, all of my digestive issues disappeared!

Keep in mind that what triggers digestive issues for me may not necessarily trigger them for you.

That said, it is safe to say that if your protein powder makes you go to the bathroom, one (or more) of these ingredients may be to blame:

🚫 Avoid Food Additives

Food additives like emulsifiers, thickeners, and flavors are hard to break down and therefore draw water into your colon, increasing the liquid content of your stool (Aliment Pharmacol Ther, 2007).

Basically, when you eat foods that are hard to digest, your body tries to flush them out, which can lead to diarrhea.

⚠️ 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 could not find an ingredient in nature or make it at home, it should not be in your protein powder.

Dairy-Based Proteins

Dairy-based proteins like whey and casein can make you poop because they contain lactose, a sugar most adults cannot fully digest.

Whey and casein are probably the top reason why protein powders make people poop.

Sugar Alcohols

Like many food additives, artificial sweeteners and sugar alcohols can have a laxative effect (Eur J Clin Nutr, 2007).

Common artificial sweeteners include sucralose and acesulfame potassium.

Common sugar alcohols include erythritol, sorbitol, and xylitol.

Insoluble Fiber

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

Most vegan protein powders naturally contain some insoluble fiber, but some protein powders, especially those intended to help with weight loss, contain added insoluble fiber.

In many cases, this added fiber is xanthan or guar gum, which are also used as laxatives (Br J Nutr, 1993).

🚫 Avoid Protein Concentrates and Isolates

Most protein supplements are made from protein concentrates and isolates, 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 it does whole foods, which could lead to digestive issues like diarrhea.

So if you have a sensitive stomach 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.

Other Reasons Why Protein Powder Can Make You Poop

Understanding the bigger picture can often help you manage your digestive issues more effectively, so here are a few more factors that can cause diarrhea and/or increased bowel movements:

Preexisting Gut Issues

When you eat protein, it enters the stomach where stomach acid and enzymes start to break it down into smaller components.

From there, the partially digested proteins move into the small intestine, where enzymes called proteases break them down into amino acids.

Amino acids are then absorbed through the intestinal lining and enter the bloodstream, which transports them throughout the body.

If any part of this complex process is not working properly due to preexisting gut issues, the protein you eat will not be fully broken down and absorbed.

Not only will this deprive you of the amino acids you need to stay strong and healthy, but it can also cause side effects like diarrhea.

Food sensitivities

Food sensitivities or allergies to certain ingredients in protein powder can trigger digestive issues like diarrhea.

Some individuals may be sensitive to soy, whey, or gluten, for example, which are found in some protein powders.

Caffeine

Some protein powders contain caffeine, which stimulates contractions in your gut and can send you running to the toilet.

Gut health

Everyone has a gut microbiome consisting of trillions of bacteria that help with digestion.

Changes to the composition of your gut microbiome caused by poor diet, medication, stress, and other lifestyle factors can impact your ability to digest foods like protein powder.

It is worth mentioning that working with a registered dietitian can help you identify any food sensitivities, triggers, or underlying gut health issues that may be contributing to your digestive issues.

How Should I Use Protein Powder If I Have a Sensitive Stomach?

Here are some practical tips and strategies on how to best incorporate protein powder into your diet if you have a sensitive stomach:

1. Gradually increase your protein intake: Start by introducing protein powder to your diet in small amounts and gradually increase the serving-size over time. This will allow your body to adapt.
2. Space out consumption: Instead of consuming a large amount of protein powder in one sitting, spread your intake throughout the day. This will help your body digest and absorb the protein more efficiently.
3. Consider individual tolerance: Pay attention to how your body reacts to different types of protein powder and choose protein powders that align with your unique dietary needs and preferences.
4. Pair with gut-friendly foods: It is beneficial to pair protein powder with ingredients that promote digestion. Consuming protein powder with fruits, vegetables, and whole grains, for example, can provide additional fiber and nutrients that support digestive health.

Remember, every digestive system is unique, so listen to your body and adjust your protein powder consumption accordingly.

By following these tips, you can optimize digestion and make the most out of your protein powder supplementation.

What Should I Do if My Protein Powder Makes Me Poop?