Why Do Protein Shakes Make Me Feel Weird?

📌 Overview and Key Takeaways

Protein shakes can cause uncomfortable symptoms like nausea, bloating, and digestive upset.

Discover how to choose protein supplements that work with your body, not against it.

Last Updated
Apr 3, 2026

Author and Medical Reviewer

Written by Jack, CNC

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

Medically reviewed by Brittany, MS, RD and Jenn, PA-C

Brittany is a Registered Dietitian with a MS in Nutrition.

Jenn is a Physician Assistant with a BA in Nutritional Sciences.

Protein Shakes Make Me Feel Weird

Why Do Protein Shakes Make Me Feel Weird?

Protein shakes can cause uncomfortable symptoms that make people feel “weird” or unwell.

In most cases, symptoms are linked to digestive issues like bloating, gas, and nausea.

Nausea, for example, disrupts your body’s normal balance and sensory perception.

This can make you feel unsteady, disconnected from your body, or uncomfortably aware of internal sensations.

To avoid feeling weird, choose protein shakes without ingredients that cause digestive problems.

Unless you have a specific food allergy or sensitivity, the most problematic ingredients are food additives, dairy-based proteins, and protein concentrates and isolates.

🚫 Avoid Food Additives

Emulsifiers, thickeners, and other additives are ultra-processed, meaning they have been heavily modified from their natural state through industrial processing.

This makes them hard to break down and absorb, which can lead to bloating, constipation, diarrhea, gas, nausea, and stomach pain.

It can also alter the composition and function of your gut microbiome – the collection of microorganisms that live in your digestive tract (North Clin Istanb, 2020).

These shifts, known as gut dysbiosis, have been linked to chronic digestive issues (JGH Open, 2021).

⚠️ Common food additives in protein supplements include:

• 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 in your kitchen, it is probably a food additive.

🚫 Avoid Dairy-Based Proteins

Dairy-based proteins like whey and casein can cause digestive issues too.

Although they are not a problem for everyone, they contain lactose, a sugar that many people cannot fully digest.

Keep in mind that 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 (Crit Rev Food Sci Nutr, 2023).

🚫 Avoid Protein Concentrates and Isolates

People with sensitive stomachs might also want to avoid 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.

For example, studies show that regularly eating protein concentrates and isolates might disrupt your gut microbiome (Nutrients, 2018).

It can also cause the formation of toxic byproducts in your gut (Mol Nutr Food Res, 2024).

Individuals with pre-existing digestive issues should look for protein supplements made from whole food protein sources like egg whites and almonds.

They are more gut-friendly.

Order Samples to see for yourself.

What Do I Do If My Protein Shake Makes Me Feel Weird?

Follow these steps if your protein shake causes uncomfortable symptoms:

1. Switch brands. Different protein supplements use different ingredients. A new brand might solve your problems.
2. Adjust the serving size. You might be consuming too much protein at once. Try using less powder to see if symptoms improve.
3. Change the timing. Drink your protein shake with food instead of on an empty stomach. This can reduce digestive problems.
4. Mix it with different liquids. Try water, milk, or plant-based milk alternatives. Some liquids may work better for your digestion.
5. Check the ingredients. Look for protein supplements with short ingredient lists. Avoid products with many additives.

If you listen to your body and experiment with these changes, you will find a protein shake that meets your nutritional needs without making you feel weird.

Sources

1. Northern Clinics of Istanbul (North Clin Istanb). Food additives and microbiota. 2020.
2. JGH Open (JGH Open). Gut microbiota dysbiosis in functional gastrointestinal disorders: Underpinning the symptoms and pathophysiology. 2021.
3. 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.
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.