You're not protein sensitive.

Posted by Adria Marshall on

I know, I know. The shock. The horror. I'm sorry to have to be the one to break this to you but it's 2023 and we need to stop with the lies and falsehoods. And the truth is this: our hair is 98% protein. So, it's already there, friend. How can your hair possibly be "sensitive" to something that's already there? Let that sink in (preferably with a heat cap).
Now, with that being said, there are some VERY GOOD reasons why you're not achieving desirable results with products that contain protein. That's what this blog is about. Let's get started!

What is Protein?

Proteins in our hair, specifically keratin, consist of amino acids, which are the fundamental building blocks of protein molecules. Amino acids are chemical compounds that contain both an acidic and a basic group within the same molecule.

The primary component of keratin is cystine, a sulfur-rich amino acid. Cystine plays a crucial role in the structure of hair, as it forms disulfide linkages within the helical structure of keratin. These disulfide bonds are primarily responsible for the mechanical strength and resilience of the hair fiber.

So, long story short, protein is what makes your hair strong.


What does the protein in hair products do?

Exposure to heat, chemicals, and environmental stress can lead to the weakening of disulfide bonds in our hair. Consequently, the cystine amino acid undergoes a conversion into a water-soluble derivative known as cystic acid. This conversion reduces the amount of cystine present in the hair while significantly increasing the concentration of cystic acid. The presence of cystic acid on the hair shaft causes it to become brittle, rough, and more prone to absorbing water (hydrophilic). This degradation of protein structure leads to higher hair porosity, increased frizz, and greater difficulty in managing the hair.

Proteins in hair products are designed to replace the eroded protein in your hair by coating, filming, or reinforcing the individual strands. They work by penetrating the hair, aligning its cuticles, and filling the empty pores inside the cortex. However, not all proteins can effectively accomplish this goal. 

The molecular weight of proteins plays a crucial role in their absorption into the hair. Proteins with a molecular weight of 1000 daltons or less are considered ideal as they are weakly cationic and can form the best bonds with the hair. On the other hand, proteins with large molecular sizes, such as those found in whole foods, may not provide long-lasting benefits to the hair when applied directly. For instance, applying a whole egg to the hair may not effectively replace lost proteins in the long run.




pH is also a factor. Proteins bond well to the hair when they are found in products between a pH of 4 and 7, with 5 or 6 being the most effective.

And, finally, if you have hair that is fine in diameter, generally speaking, a medium to large protein can give you the strengthening and conditioning effects you are looking for. If your hair is more coarse, smaller proteins are more effective. And speaking of diameter, fine hair typically requires protein more regularly than its coarse counterpart. Protein deprivation in fine hair can often come across as a dry/unmoisturized feeling. What most girls with fine-textured curls are really feeling is protein deprivation instead of lack of moisture. Conversely, if your hair is coarse, it's, by nature, stronger than fine hair. Therefore, it doesn't need protein nearly as often as fine-haired curlies.

So, why might you think you're protein sensitive?

Now that you have a good understanding of what protein is, why it's important to have in it in your hair products and how it is or isn't absorbed, let's discuss some reasons why your own experience with protein might have been less than desirable.

You're coarse

If your hair's diameter is coarse (wider than a piece of sewing thread), you don't need to protein treat as frequently as someone with fine hair. This doesn't mean that you're protein sensitive! It's still critical for you to determine the proper cadence of protein-treating to replenish lost protein and keep your hair strong.

The protein in your product is the wrong size

If your hair is coarse and your deep conditioner contains a protein with a large molecular weight, it might just be siting on your hair strands instead of being absorbed. Depending on the treatment, this can leave you with dry, unruly and flaky results. Likewise, if the protein that you're using isn't hydrolyzed (egg, for instance), it could cause a similar problem. Similarly, your hair simply might not agree with a certain type of protein. This doesn't mean that you should give up on ALL protein, though! Just look for a protein that works better for your hair type.

You're not following up with a deep conditioner

Because effective protein penetration increases the rigidity of your hair, its critical to follow up with a moisturizing deep conditioner to add back softness and elasticity! Skipping this step can leave you with hair that is hard, dry and brittle and make you feel that the protein is to blame when that is simply not the case. 

The ph in your product is too high

Not getting good results from your protein treatment? Inquire about its ph value! Remember that to be most effective, the ph should be a 5 or 6.

You're not clarifying beforehand

If your hair has buildup, the effectiveness of your protein treatment will be severely compromised. The cuticles of your hair shaft need to be as clear as possible in order for the protein molecules to be absorbed. Otherwise, the treatment will simply sit on top of your hair, providing little to no benefit.

You're not using a heat cap


Using heat on natural/curly hair is usually viewed as a bad thing. However, to best ensure that your protein treatment absorbs, bring out the hooded dryer, heat cap or steamer. This is especially important if you're low porosity! Otherwise, the protein molecules will just hang out on your hair shaft, unable to penetrate, causing a slew of undesirable or ineffective results.

Until February,



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  • Wow! So glad I came across this post! Thanks for the information.

    Tonya on
  • So interesting. So why is hair a mess post covid?

    Lenora on
  • I have 2c hair (mostly wavy with some curly parts) I think I can get more curl with the right products. It’s not coarse. Which products should I use?

    Sarah Ramirez on
  • Adria,

    Thank you, your blog posts are always so educational!

    Michelle Barczykowski on

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