Can protein powder make you poop more often? For some people, yes it can. For others, protein powder can cause constipation and blockages.
Protein powder can have a dramatic effect on bowel movements and digestion, which can attributed to factors like the type of protein (whey vs plant protein), added ingredients, and individual tolerance.
It’s also important to consider the absorption rate of the protein powder and its interaction with other dietary components, such as fat and fiber, which can also influence how frequent (or infrequent) you poop.
Here are some of the most common reasons why protein powder can make you poop more or just inconsistently.
Fiber Moving Things Forward
Many protein powders pack more than just protein. They can also loaded with dietary fiber. For instance, PB2 Performance Protein packs 6-8 grams of fiber per serving, depending on the flavor.
While PB2 Performance Protein is a high-fiber anomaly that contains prebiotic inulin (along with roasted peanuts and brown rice protein,) other types like pea and hemp protein are also common sources that provide ample fiber.
Prebiotic fiber, like inulin, is a frequently added ingredient in protein powders which can contribute to more frequent poops.
Aside from these additives, plant-based options often contain higher fiber content naturally, such as the case with pea, seeds, brown rice, and quinoa protein.
If you’re sensitive to fiber, you may want to opt for grain-free protein powders or isolates that contain very little carbs/fiber and mostly just protein.
Fiber is a major factor to consider with vegan protein powder, but it’s less of a factor with whey protein powder, which generally contains little to no fiber.
Sugar Alcohols’ Laxative Effect
With the health push for sugar-free protein powders has come an onslaught of artificial sweeteners and sugar alcohols.
Although these sweeteners contain zero sugar, a lot of them (such as erythritol) have serious health concerns to be mindful of. There are now many studies that point to problems with artificial sweeteners. Frequent poops are probably the least concerning.
Sugar alcohols in particular can have a laxative effect, leading to increased bowel movements. Common sugar alcohols–like erythritol, sorbitol, and xylitol–can disrupt the gut and contribute to this effect, including reports of diarrhea.[1]
Additionally, artificial sweeteners and other additives in protein powder may also trigger digestive issues, resulting in more frequent bowel movements.
Always have a look at labels for sugar alcohols and other additives in protein powder. I generally steer clear of synthetic sweeteners and opt for natural ingredients like monk fruit sweetener.
Lactose Sensitivity Can Mean Looser Stools
While many active types turn to whey or casein-based protein powder for its muscle-building benefits, these dairy-based supplements can spell disaster for those who have a lactose intolerance.
Lactose intolerance stems from a lactase deficiency, the enzyme responsible for breaking down lactose found in dairy products. Without sufficient levels of this crucial enzyme, your body struggles to process this sugar properly which often leads to gastrointestinal distress including increased bowel movements and diarrhea.
When undigested lactose ferments in the colon, it creates gases and short-chain fatty acids that draw water into the gut, which results in looser stools.[2] It’s not just about discomfort; it can be seriously life-disrupting.
In most cases, this is caused by whey protein concentrate, a less processed and more lactose-rich option. Whey protein isolate, on the other hand, undergoes additional processing, which significantly reduces lactose levels.
See my post on lactose-free protein powder for more on this topic.
Undigested Additives Adds to Your Bowel Movements
Protein powders often contain additives such as emulsifiers, stabilizers, thickeners, sweeteners, and flavors that can affect your digestive system. These substances are highly processed and may be difficult for your body to fully break down during digestion.
When these partially digested ingredients reach the colon, they tend to attract water due to their high osmotic load. This term refers to the dense concentration of undigested particles—or solutes—in the intestines.
Because there’s a higher number of these particles on one side of the intestinal walls than on the other—inside your gut versus inside your cells—the body tries to balance this out.
It does so through osmosis: water moves across the gut wall (which acts like a filter) towards where there’s more stuff dissolved in it – those unabsorbed food bits. This movement is driven by what we call ‘osmotic pressure.’
The result? More water ends up in your stool than usual which can make it looser or even lead to diarrhea if too much liquid accumulates.[3]
In simpler terms: when you consume protein powder with lots of additives that aren’t fully digested, they draw extra water into your bowels which could increase bowel movements or cause loose stools.
Optimize Your Protein Powder for Predictable Poops
Are you wondering if protein powder could be affecting your bathroom habits? You’re not alone. Many folks notice changes when they start supplementing with protein powders.
It mostly comes down to your digestive health and the fiber, flavorings, lactose, and additives in these products.
Some products have high fiber, which your body might not be used to. Other protein powders may not have enough. Add to the mix sugar alcohols and added fillers, and you have a recipe for having weird and unfamiliar bowel patterns.
Also, you probably shouldn’t be using more than a few scoops per day of protein powder. Remember, it’s a supplement a not whole food meal, so don’t over-rely on protein powder as your sole protein source.
You can strike a balance with a clean, plant-based protein powder with minimal added ingredients and moderate amounts of fiber.
PlantFusion Complete Protein, Orgain Simple Protein, and OWYN Plant Protein are three that fit the bill. I frequently enjoy these products for their delicious taste, nutrient density, and digestion-friendly benefits.
You Might Also Like
- Dairy-Free Protein Powder: Best-Tasting and Best for You
- What’s the Best Gluten-Free Protein Powder? (Vegan)
- How is Protein Powder Made? An In-depth Look
About The Author
This review was conducted by Tyler Tafelsky, the lead editor here at VeganProteinPowder.reviews. Tyler is an experienced writer in the health, nutrition, and athletic space. Over his lifetime, he’s tried hundreds of plant-based nutritional products and writes about his favorites here on this blog. Learn more about Tyler by viewing his full author bio or by following him on social media platforms like LinkedIn, Twitter, Facebook, Pinterest, or Instagram. Also, visit his website to learn more about what he’s up to.
Scientific References
- Mäkinen KK. Gastrointestinal Disturbances Associated with the Consumption of Sugar Alcohols with Special Consideration of Xylitol: Scientific Review and Instructions for Dentists and Other Health-Care Professionals. Int J Dent. 2016;2016:5967907. doi: 10.1155/2016/5967907. Epub 2016 Oct 20. PMID: 27840639; PMCID: PMC5093271.
- Deng Y, Misselwitz B, Dai N, Fox M. Lactose Intolerance in Adults: Biological Mechanism and Dietary Management. Nutrients. 2015 Sep 18;7(9):8020-35. doi: 10.3390/nu7095380. PMID: 26393648; PMCID: PMC4586575.
- Nemeth V, Pfleghaar N. Diarrhea. [Updated 2022 Nov 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK448082/