If you're part of the curl community you've probably heard of protein overload. If you haven't, it's basically the idea that too much protein in hair products causes hair to become dry, brittle, stiff and prone to breakage. To fix it you need to restore the "protein-moisture balance" by reducing protein and increasing moisture.

Many people report that they've experienced this phenomenon, yet I could find NOTHING in the scientific literature about it. I honestly kind of gave up until I accidentally stumbled upon something written in an obscure chemistry book from the 90s.

What I learned basically overturned everything I thought was true about both protein and moisture. Turns out that a lot of what we think of about moisture is completely backwards. There IS a scientific explanation for "protein overload" but it might not be what you think.

If you need a TLDR click on the last section in the TOC below!

Not your grandma's protein

I started my journey by reading Conditioning Agents for Hair and Skin (1999), which has a whole chapter on proteins by cosmetic chemist Gary Neudahl. Humans have been using protein treatments in their hair for a long time, from camel milk in Africa to rice in Asia. But the protein in our modern hair products doesn't look anything or behave like the protein in a whole food like milk or rice.

Almost all protein in hair products is hydrolyzed, a chemical process that breaks the protein up into smaller pieces. Hydrolysis was first developed in the 1800s, but it wasn’t until the early 1900s that scientists working with wool discovered something important: dye baths containing hydrolyzed proteins caused less damage to the fibers. They realized this could be super useful for a fashionable, but super damaging new hair technique: the perm! And early perms were WAY more damaging than perms today.

High porosity hair is damaged hair, and it's easier for stuff to get in

Damaged hair has a cracked and chipped cuticle, this is sometimes called "high porosity" because it allows substances like water and these broken up protein pieces. The scientists theorized that the smaller pieces in the hydrolyzed proteins were actually being absorbed by the damaged permed hair, making it stronger. Early protein hair products were often post-perm treatments, which were the first modern conditioners.

But that wasn't the only use for proteins in hair products.

Protein IS Moisture

Turns out proteins are also added to products as a humectant, an ingredient that attracts and retains moisture!^[10]

Hydrolyzed protein is a humectant

I thought perhaps protein's humectancy was key to "protein overload" since in very dry and very wet conditions, theoretically humectants could attract water a little too greedily and pull water out of the hair. And protein wasn't as good as holding on to moisture as other common humectants, making it extra desperate for more water.

Hooray! Mystery solved!

Except not. Lab Muffin's video called "Is hydration destroying your hair? The REAL science" completely changed everything I believed about moisture and ruined that theory. It led me to the writing of Trefor Evans, another cosmetic scientist. In his Practical Modern Hair Science book, he explains that the most recent science shows that hair products can't really change the amount of moisture in hair ^[16]. That how much water your hair contains is mostly determined by the humidity of the air around you. Water molecules are tiny and they aren't deterred by whatever products you think might be able to "seal" them out.

Literally not what it looks you, but you get the idea

And even if you could add more moisture to hair, you wouldn't want to. Turns out studies found that hair that feels "more moisturized" has LESS water content than hair that feels "dry."

So when people say "moisturized" they actually don't mean anything to do with water, they just mean better CONDITIONED. In retrospect this makes sense, because unless you live in some place with really nice weather, we all know that humidity makes our hair look and feel worse.

Either way, knowing this, I no longer thought protein's role as a humectant played any role in the mystery of protein overload. But it did lead to me reading more about conditioning, which helped me unravel the mystery.

Conditioning is the key to EVERYTHING

Protein's role in hair products is not limited to being just a humectant. Most proteins, even the hydrolyzed ones, are not small enough to get into hair itself. But cosmetic scientists found proteins could form films that help condition the hair. Conditioning is, in short, the process of making hair feel smoother, softer, and more manageable, as well as protecting it from damage. And here's where things get sticky...literally.

Pre mid-twentieth century if you wanted to condition your hair, your options were fats like oils and tallow. But the major weakness of fats is they aren't very good at conditioning damaged hair. Healthy hair has a fatty top layer called the F-layer, and fats attract fats, so fats like oils will like to stick to it to make it better conditioned. But damaged hair lacks this layer and if you try to condition it with oil it just mostly rinses out.

Sadly IRL these things don't have cute faces

In the mid-twentieth century, chemists invented the process that is the foundation for nearly every single modern conditioner: quaternization. This is too complicated to explain unless you're also a chemist but the important point was it gave chemicals a positive (cationic) charge. Damaged hair might lack the fat layer, but what it does have is a negative charge and in chemistry opposites attract. This was a new way to make ingredients stick to hair, even damaged hair.

Turns out you could quaternize proteins! And these proteins were extra good at sticking to damaged areas of the hair! It made an excellent conditioner for damaged hair. Sounds perfect right?

Conditioning's Dark Side

Turns out you can have too much of a good thing and that includes conditioning ingredients. While "protein overload" might not be in scientific texts like Conditioning Agents for Hair and Skin, "buildup" is. Buildup is the gradual accumulation of products, minerals, or environmental residues on the hair, which can affect how it feels and behaves.

The signs of conditioner buildup are usually greasy, limp, weighed down hair. Or so I thought.

To learn more about conditioning I picked up Principles of Polymer Science and Technology in Cosmetics and Personal Care. It's another book from the 1990s in the same series as Conditioning Agents for Hair and Skin. I noticed Principles of Polymer Science had a chapter on protein and it was I read something that helped me solve the protein overload mystery.

In all my research into protein in hair products, I never found any scientific literature that mentions any potential downsides. But here in the chapter Proteins in Cosmetics, by Italian cosmetic scientists Teglia and the other guy, they warn about protein buildup^[12]. Turns out that proteins, especially those modified to be more sticky, can buildup on the hair just like any other positively charged conditioning agent. But here was the important part: it wasn't like the regular limp greasy conditioning buildup we think of when we hear the word buildup. Turns out that some protein buildup can feel stiff and rough. And that proteins could possibly even buildup on top of each other, forming layers of ever worse buildup.

NOT what it really looks like, but it's a good illustration of what I'm talking about

I decided to ask the cosmetic scientists Valerie George and Perry Romanowski on Beauty Brains about this because I'd heard George introduce the possibility that protein overload is just buildup in previous episodes. She agreed that so-called "protein overload" could be buildup from using too many high protein products without washing them out adequately^[38]. In another episode also noted that interestingly wheat protein tends to form stiff, brittle films, but pea and soy don't ^[15].

In other chapters of Principles of Polymer Science and Technology, I learned that OTHER types of buildup can be stiff. Some other conditioners that can form stiff buildup are silicone and cellulose polymers. So it turns out protein can cause this stiff conditioning buildup, but so can other things, and not all protein causes it.

So protein overload is just buildup?

Basically it seems protein overload is a type of conditioner buildup, and it's likely that moisture overload is too. Just different types of conditioning buildup: one stiff and rough, the other soft and limp.

If this is true, it can be treated like any other buildup

So I should avoid protein products

No! I hope you don't think that. There are SOOOO many types of protein. And TBH so many types of protein containing products, some of which are questionable.

You see I then had to understand where the whole concept of "protein moisture balance" comes from. The first mention of the term (at least among texts indexed by Google Books) is in the book about Black hair from 2002, called Beautiful Black Hair: Real Solutions to Real Problems which also mentioned a protein hair product I'd never heard of: protein reconstructor.

Now some of you, especially if you aren't American, might be like "Black hair"? But Black hair in America has a distinct culture and history. If you want to learn about it the book Hair Story: Untangling the Roots of Black Hair in America is a good start.

Products called "protein reconstructors" start showing up in American Black media like Ebony magazine in the 1980s. This was an interesting period in the unique history of Black hair because the fashion for afros and natural hair of the 1970s was starting to fade ^[39].

Ice Cube rocking the Jheri curl in the 1980s. (Public Domain)

In its place came our old friend: perms like the Jheri curl. And with perms came protein treatments that were used alongside them to counteract some of the damage. These protein treatments also started to be used with other damaging chemical treatments like relaxing.

I couldn't find the exact ingredients lists of "protein reconstructors", but I did find them described in a cosmetic chemistry book ^[40]. The sample product has 3% Hydrolyzed keratin and 2% Laurdimonium hydroxypropyl hydrolyzed collagen (which is a "sticky" positively-charged type of protein) for a total of 5% protein. To contrast Perry says products he formulated, like the v05 volumizing shampoo, have more like .1% protein.

The other important factor with Jheri curls and similar perms is that they made the curl pattern much looser, more like wavy hair. That meant many traditional products used in Black hair were too heavy and weighed it down. This led to the development of humectant based alternatives such as "curl activators," but while these were light, they were far less effective as conditioners compared to the old school products^[41]. It's no wonder such hair was uniquely vulnerable to basically... everything.

While the fashion for perms has faded in the Black hair community, protein treatments have remained a staple of many brands associated with Black hair. And in the 2000s a lot of people who weren't Black discovered these brands like Shea Moisture and started using them without understanding who these products were really for. And thus "protein overload" spread from the Black hair community to the mainstream curly community, devoid of its original context.

The protein-moisture balance thing makes a whole lot more sense when you think about the context of Black hair that is already prone to breakage then subjected to damaging chemical treatments, which also prevented usage of traditional conditioners (since it would weigh the hair down). Brittle buildup on such hair could be catastrophic. It's actually a shame that scientists didn't investigate this phenomenon, but in general Black hair is under-studied. While the language might not be consistent with what we now know about protein and moisture, books like Beautiful Black Hair did describe a real phenomenon and helped people deal with it.

The question is why is "protein overload" seem to be so prevalent now? And not just in people with permed hair.

Trying to give myself protein overload

There was only one answer: to give myself protein overload by piling on every single protein product in my cabinet, atop my already hennaed hair (and many people consider henna to be a protein treatment).

Unfortunately I was unsuccessful. My hair remained as it always is: more prone to the soft limp type of buildup. However, in the microscope I did notice occasional grainy things that could have been product buildup, and if there were more of them I can imagine they might feel rough and unpleasant. The grainy stuff easily washed out with a clarifying shampoo.

I literally did this with a paper microscope (the Foldscope) which is super cheap if you want to try it

While many people say low porosity hair shouldn't use protein for silly reasons I've debunked here, I think I would have had an easier time giving myself stiff buildup back when my hair a bleach blonde high porosity disaster. The proteins would have stuck to it better.

I also think all my protein products are pretty well-formulated. I suspect that much protein overload comes from smaller brands with outdated or poorly designed formulations. Not everyone who makes hair products is a cosmetic chemist!

The only high protein treatment I had was the Curlsmith Bond Curl Rehab, which I've used pretty often and never had issues with. It uses some fancy chia seed protein called ProCutiGen® Bond. The rest of my products generally seemed to have very small amounts of protein.

I also use real shampoo! Sometimes I use a gentle curl shampoo but at least once a week I use a stronger shampoo for clarifying.

I think the ideal way to get "protein overload" is:

• use shampoos that don't cleanse very well or don't use real shampoo
• use very high protein masks, deep conditioners, and treatments from companies have outdated or poorly tested formulations
• don't use good conditioners for high porosity hair (which needs special conditioners because damaged hair is different)
• have high porosity hair

Unfortunately the first three things were basically staples of the curly community in the past couple of decades.

I don't think you're likely to get this "protein overload" thing if you're someone with normal hair using like a mainstream drugstore conditioner with like .1% protein and using actual shampoo.

So how do I get rid of protein overload (really just buildup) if i have it

The same way you get rid of other buildup probably. Though I haven't tested this since I sadly was unable to give myself the condition.

1. First I'd look into water quality. Could you have hard water? If so you need to remove that buildup first, and frankly removing it might just solve all your problems. I have a guide to hard water that you can read here on this.
2. Then I'd use a clarifying shampoo. You don't necessarily need to go nuclear with drugstore clarifying shampoos, you can definitely use a specially formulated clarifying shampoo for curls, which is going to be a bit less harsh. I like Bounce Curl's Gentle Clarifying.
3. Finally, do you have high porosity hair? If you don't know, take our quiz. If you DO have high porosity hair consider using a specially formulated conditioner for it. I have some listed here and at the drugstore L'Oreals EverPure is a good option.

OK how can I avoid this protein overload thing ever happening again?

Now you probably want to take a hard look at your haircare products. The products you want to pay special attention to are:

• Masks and deep conditioners
• Treatments
• Leave ins
• Gels/Mousses

Make note of what kind of protein they have. That might be the protein that's the problem for you, but keep in mind that ingredients in products are complicated. Like hydrolyzed collagen can be more or less sticky depending on how it's manufactured. Ingredients lists also don't have to list the percentage of protein.

With gels and mousses it is not necessarily protein that is making your hair feel stiff and dry, as there are other common polymers that can form stiff buildup.

The only way to really know a product is to try it or get reviews from someone with a similar hair type. If you're super dedicated you could also keep hair swatches to test products on.

You can also look into whether the company you buy products from has a reputable R&D department, because these generally do a better job testing a product to make sure it doesn't cause buildup. Like L'Oreal which own A TON of brands like Redken and Garnier, has one of the biggest and most prestigious R&D departments in the world.

If you want to get super nerdy, you might look for brands that are transparent and then you can look up the ingredient. For example, Curlsmith identifies their chia protein as ProCutiGen® Bond, a branded ingredient whose manufacturer has published several studies that are available for review. Another new-ish protein ingredient is Keravis (Hydrolyzed Vegetable Protein PG-Propyl Silanetriol), which is a copolymer of hydrolyzed vegetable protein and silicone. Despite the intimidating name, it has been shown to form a flexible film in studies, which isn't surprising since silicones are quite flexible.

You could also do your own experiments at home such as spreading the product on a glass slide and seeing what kind of film it forms (smooth or rough). You could do multiple layers to see what films might be like if they built up on top of each other.

Finally, you could consider incorporating more products into your routine that are known to form soft flexible films like the much-maligned silicones. Amodimethicone for example, which is also known not to form layers of buildup ^[1].

Mystery Solved?

I think the most important things my journey emphasizes are:

• Protein IS moisture, but moisture in terms of literal water content isn't necessarily good
• "Moisturized" really just means better conditioned, not more water
• Protein overload is likely a type of buildup
• Basically any conditioning ingredient can buildup, not just silicones
• There are TONS of different types of proteins in haircare products and they are all VERY different, so just because you don't like some doesn't mean you need to avoid them all

My understanding of haircare hasn't been the same since. Maybe the hair community needs to get rid of using words like "moisturization" if we want to talk about hair scientifically? But I don't think that's happening anytime soon.

If you want to read more about protein, Science-y Hair Blog has several posts on it.

Also TBH some of the books I reference are from the 1990s, so super old...wait, am I super old? One of them literally fell apart when I was reading it and my boyfriend had to apologize to the librarian when he returned it. So if you know of any papers or books I should absolutely read, drop me a line!