Why do protein shakes make my stomach hurt?

Why do protein shakes make my stomach hurt?


Protein shakes have become increasingly popular among fitness enthusiasts and those looking to supplement their diet with additional protein. While protein shakes are generally considered a convenient and effective way to meet daily protein requirements, some individuals may experience stomach discomfort after consuming them. In this article, we will explore the reasons why protein shakes can cause stomach pain and discuss potential solutions to alleviate this issue.

Possible Causes of Stomach Discomfort

1. Lactose Intolerance: Many protein shakes contain dairy-based proteins such as whey or casein. If you are lactose intolerant, meaning your body lacks the enzyme lactase needed to digest lactose, consuming dairy-based protein shakes can lead to stomach pain, bloating, gas, and diarrhea. Opting for lactose-free protein shakes or those made with plant-based proteins can be a suitable alternative.

2. Allergies or Sensitivities: Some individuals may have allergies or sensitivities to specific protein sources commonly found in protein shakes, such as soy, eggs, or gluten. Allergic reactions or sensitivities can manifest as stomach pain, nausea, vomiting, or even skin rashes. Identifying the specific allergen or sensitivity through allergy testing or an elimination diet can help determine which protein sources to avoid.

3. Artificial Sweeteners: Protein shakes often contain artificial sweeteners like sucralose or aspartame to enhance taste without adding extra calories. However, these sweeteners can cause digestive issues in some individuals, including stomach pain, bloating, and diarrhea. Switching to protein shakes sweetened with natural alternatives like stevia or opting for unsweetened varieties may help alleviate these symptoms.

4. Poor Digestion: Some individuals may have difficulty digesting protein shakes due to various factors, such as low stomach acid production or impaired digestive enzyme function. Inadequate digestion can lead to stomach discomfort, bloating, and gas. Taking digestive enzyme supplements or consuming protein shakes alongside meals can aid in digestion and reduce the likelihood of stomach pain.

5. High Protein Intake: Protein shakes are designed to provide a concentrated amount of protein in a convenient form. However, consuming excessive amounts of protein can overwhelm the digestive system, leading to stomach discomfort. It is important to ensure that your protein intake aligns with your individual needs and consult with a healthcare professional or registered dietitian for personalized recommendations.

Tips to Reduce Stomach Discomfort

1. Choose the Right Protein Shake: If you experience stomach pain after consuming protein shakes, consider switching to lactose-free or plant-based options. Additionally, selecting protein shakes without artificial sweeteners or allergens you may be sensitive to can help alleviate discomfort.

2. Gradually Increase Protein Intake: If you are new to protein shakes or have recently increased your protein intake, it is advisable to start with smaller servings and gradually increase the amount over time. This allows your body to adjust and minimize the risk of digestive issues.

3. Consume Protein Shakes with Meals: Instead of consuming protein shakes as standalone snacks, try incorporating them into your meals. Consuming protein shakes alongside other foods can help slow down digestion and reduce the likelihood of stomach discomfort.

4. Stay Hydrated: Ensure you are adequately hydrated when consuming protein shakes. Drinking enough water can help facilitate digestion and prevent constipation, which can contribute to stomach pain.

5. Seek Professional Advice: If you consistently experience stomach discomfort after consuming protein shakes, it is recommended to consult with a healthcare professional or registered dietitian. They can assess your individual needs, identify potential underlying causes, and provide personalized recommendations.


While protein shakes are a popular choice for individuals looking to increase their protein intake, they can cause stomach discomfort in some cases. Lactose intolerance, allergies or sensitivities, artificial sweeteners, poor digestion, and excessive protein intake are potential factors contributing to stomach pain. By selecting the right protein shake, gradually increasing protein intake, consuming shakes with meals, staying hydrated, and seeking professional advice when needed, individuals can minimize or alleviate stomach discomfort associated with protein shakes.


– Mayo Clinic: Protein shakes: Good for weight loss? – mayoclinic.org
– National Institute of Diabetes and Digestive and Kidney Diseases: Lactose Intolerance – niddk.nih.gov
– American College of Allergy, Asthma & Immunology: Allergic Reactions – acaai.org
– National Center for Complementary and Integrative Health: Artificial Sweeteners – nccih.nih.gov
– Academy of Nutrition and Dietetics: Protein and the Athlete – How Much Do You Need? – eatright.org