Can Meal Replacement Shakes Cause Constipation?

📌 Overview and Key Takeaways

Can meal replacement shakes cause constipation?

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

Last Updated
May 19, 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.

Meal Replacement Constipation

Do Meal Replacement Shakes Cause Constipation?

Yes, meal replacement shakes can cause constipation.

Meal replacement constipation is a common side effect, but one that can be easily avoided.

Keep reading to learn how to add a meal replacement to your diet without upsetting your stomach.

Why Do Meal Replacements Make Me Constipated?

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

The most common symptoms are bloating and stomach pain.

Unless you have a food allergy or sensitivity, meal replacement constipation has nothing to do with the type of meal replacement you are consuming.

That is, both animal and plant-based meal replacements can make you constipated.

What causes constipation is often the food additives.

🚫 Avoid Food Additives

Certain emulsifiers, thickeners, and other ultra-processed additives are notorious for causing digestive issues, including constipation.

This is likely because they resist full digestion in the small intestine, reaching the large intestine where gut bacteria ferment them and release gas as a byproduct.

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

This might reduce intestinal motility – the movement of the muscles in the intestines – leading to constipation (J Neurogastroenterol Motil, 2015).

⚠️ Here is a list of the most common food additives in meal replacements:

• 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 an ingredient 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 a problem for everyone, can cause digestive issues too.

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.

For starters, the digestion of some caseins releases a bioactive peptide that has been linked to digestive issues (Adv Nutr, 2017).

Casein also forms a gel-like substance in your stomach that slows down digestion (Crit Rev Food Sci Nutr, 2023).

For sensitive individuals, particularly true for those with cow’s milk protein allergy or intolerance, slower digestion can contribute to bloating, constipation, and other side effects.

🚫 Avoid Protein Concentrates and Isolates

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

Most meal replacements contain one or both of these ultra-processed protein sources, which have been mechanically and 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 meal replacements made from minimally-processed protein sources like egg whites and almonds.

They are more gut-friendly.

Order Samples to see for yourself.

How Do I Relieve Meal Replacement Shake Constipation?

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

• Hydrate: Drinking lots of water, especially warm or hot water in the morning, softens your stools.
• Exercise: Movement can stimulate the muscles in your intestines.
• 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.
• Drink Coffee: Caffeine can stimulate involuntary muscle contractions in your colon.
• Use a Laxative: If all else fails, try a laxative. Most laxatives can be purchased over-the-counter. I put this last on the list because laxatives have potential side effects, such as allergic reactions, dehydration, and vitamin deficiencies.

Keep in mind that everyone is different.

What works for you might not work for someone else.

Remember to be patient too.

Most of these remedies take 12 to 72 hours to work.

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. Northern Clinics of Istanbul (North Clin Istanb). Food additives and microbiota. 2020.
4. Frontiers in Microbiology (Front Microbiol). Causal relationship between gut microbiota and constipation: a bidirectional Mendelian randomization study. 2024.
5. Advances in Nutrition | Journal (Adv Nutr). Systematic Review of the Gastrointestinal Effects of A1 Compared with A2 β-Casein. 2017.
6. Critical Reviews in Food Science and Nutrition (Crit Rev Food Sci Nutr). Milk proteins: Processing, gastric coagulation, amino acid availability and muscle protein synthesis. 2023.
7. Nutrients (Nutrients). Effect of a Protein Supplement on the Gut Microbiota of Endurance Athletes: A Randomized, Controlled, Double-Blind Pilot Study. 2018.
8. 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.

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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.