The Uncomfortable Impacts of Whey on the Body: Separating Fact from Fiction

The Uncomfortable Impacts of Whey on the Body: Separating Fact from Fiction

Whey protein is a popular supplement among fitness enthusiasts and athletes, lauded for its muscle-building properties and ease of absorption. Derived from milk during the cheese-making process, whey is a complete protein containing all nine essential amino acids. However, despite its many benefits, some individuals experience uncomfortable side effects when consuming whey protein. In this article, we will delve into the science behind these uncomfortable impacts and provide recommendations for addressing them.

  1. Lactose Intolerance

Lactose intolerance is one of the primary reasons individuals may experience discomfort when consuming whey protein. Approximately 65% of the world's population has a reduced ability to digest lactose, the sugar found in milk and dairy products (NIH, 2021). This is due to the decreased production of lactase, the enzyme responsible for breaking down lactose, as individuals age. Undigested lactose in the gut can cause symptoms such as bloating, gas, diarrhea, and stomach cramps (Mayo Clinic, 2021).

Solution: Opt for lactose-free proteins. There are many great protein sources such as pea, fava, soy, or rice protein.

  1. Allergies

Milk allergy is another factor that can contribute to discomfort after whey protein consumption. Individuals with a milk allergy have an immune response to the proteins in milk, including whey (AAAAI, 2021). Symptoms can range from mild, such as hives, to severe, like anaphylaxis. It is important to note that a milk allergy is distinct from lactose intolerance, as the former involves the immune system, while the latter does not.

Solution: Seek out alternative protein sources and consult with a healthcare professional to develop a personalized nutrition plan.

  1. Gastrointestinal Discomfort

For some, whey protein consumption can lead to gastrointestinal issues such as bloating, gas, and stomach cramps. These symptoms may occur due to the rapid absorption of whey protein, which can lead to a temporary increase in the concentration of amino acids in the blood (Macnaughton et al., 2016). This rapid absorption may contribute to an osmotic imbalance in the gut, drawing water into the intestine and causing diarrhea (Gorissen et al., 2018).

Solution: Consume whey protein in smaller doses, opt for a slower-digesting protein like casein, or try alternative plant-based proteins.

  1. Acne

Although the relationship between diet and acne is complex, some studies suggest a potential association between whey protein consumption and acne development (Koutroubakis & Marrero, 2020). Whey protein may increase the production of insulin-like growth factor-1 (IGF-1), which can stimulate the production of sebum and lead to acne (Melnik, 2012). 

Solution: Monitor your skin's response to dairy products and whey protein and consult a dermatologist if you suspect that it may be contributing to acne.

5. Hormone Imbalances

Hormones in dairy products and whey protein, such as insulin-like growth factor-1 (IGF-1) and bovine growth hormone (bGH), can impact human health. Increased IGF-1 levels, found in dairy, are associated with acne and a higher risk of certain cancers. However, the relationship between dairy and cancer risk is complex. Synthetic bGH (rBST) is used in some countries to increase milk production, leading to higher IGF-1 levels and potential antibiotic resistance due to increased mastitis incidence in cows.

Many dairy products and whey proteins are labeled as "rBST-free" or "hormone-free," allowing consumers to choose hormone-free options. Overall, while hormones in dairy and whey protein can have potential side-effects, the relationships between dairy consumption, hormone levels, and health outcomes require further research.

Solution: Seek out certified "hormone-free" or alternative protein sources if you are concerned about hormone-related side effects.



While whey protein may seem like a highly beneficial supplement for many individuals, it can cause many uncomfortable side effects. Lactose intolerance, milk allergy, gastrointestinal discomfort, and acne, and hormone imbalances are just some of the potential issues to be aware of when incorporating whey protein or other dairy products into your diet. Fortunately, solutions exist for most of these problems, including opting for lactose-free or alternative protein sources, consuming smaller doses, and seeking medical advice when necessary. As with any dietary supplement, it is essential to listen to your body and consult with a healthcare professional before making significant changes to your nutrition regimen.




  • AAAAI. (2021). Milk Allergy. American Academy of Allergy, Asthma & Immunology. Retrieved from
  • Gorissen, S. H. M., Crombag, J. J. R., Senden, J. M. G., Waterval, W. A. H., Bierau, J., Verdijk, L. B., & van Loon, L. J. C. (2018). Protein content and amino acid composition of commercially available plant-based protein isolates. Amino Acids, 50(12), 1685-1695.
  • Koutroubakis, I. E., & Marrero, S. (2020). Diet and acne: an exploratory review of the role of dairy, sugar, and whey protein. Journal of the European Academy of Dermatology and Venereology, 34(8), 1602-1608.
  • Macnaughton, L. S., Wardle, S. L., Witard, O. C., McGlory, C., Hamilton, D. L., Jeromson, S., ... & Tipton, K. D. (2016). The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein. Physiological Reports, 4(15), e12893.
  • Mayo Clinic. (2021). Lactose intolerance. Retrieved from
  • Melnik, B. C. (2012). Dietary intervention in acne: Attenuation of increased mTORC1 signaling promoted by Western diet. Dermato-endocrinology, 4(1), 20-32.
  • NIH. (2021). Lactose Intolerance. National Institute of Diabetes and Digestive and Kidney Diseases. Retrieved from
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