Why moisturising is underestimated

Skincare can seem more like a fine art than a straightforward part of everyday self-care, especially these days, with a new hero ingredient popping up every few months, often accompanied by all kinds of claims of magical skin-saving qualities. Brands and influencers are quick to promote exciting new ‘solutions’ to potentially stressful skin concerns like acne, wrinkles, and stretch marks.

The obsession with the ‘latest thing’ frequently obscures the fact that often the most well-known skincare practices are not only the most effective, but also the best documented in clinical and scientific literature.

No matter how much trend-led fast fashion marketing would like us to forget it, we all know high-quality, well-made classics are the real key to building a great wardrobe you always feel good in - why should skin be any different? 

Perhaps the best example of this is the simple act of moisturising. You might be thinking ‘well of course moisturising is important, everyone knows that’ but what the deluge of 7-step routines and hero-ingredient ‘treatments’ might have obscured is that moisturisation can be just as good (if not better, in some cases) at preventing or minimising the appearance of a whole host of common skin concerns as the more complicated combinations of products, tools, and interventions. Like a perfect pair of jeans or a versatile LBD, the often-underrated moisturiser is the best tool you can reach for to help your skin perform its many functions. 

With stretch marks, for example, though there are many topical treatments claiming to prevent or minimise their appearance, there isn’t very strong scientific evidence for any of their claims. The best-evidenced topical treatment (vitamin A) is unsafe for pregnant people, the group most likely to get stretch marks. There is, however, lots of good science behind why we should all moisturise and how regular moisturisation helps support your skin’s health.

Healthy, well-moisturised skin is much less vulnerable to the kind of dramatic tearing that causes stretch marks and in a better position to adapt to the changes and pressures of pregnancy, puberty, or rapid weight gain. 

If you want to learn more about stretch marks, you can go to our article here.

A regular ritual with a well-formulated moisturising product that sustains hydration in your skin is an often-overlooked, but beautifully simple supportive step to the best possible outcome for your skin. 

Why moisturise?

In order to unpack the answer to the question ‘why should we moisturise’ we first have to take a step back, in order to better understand our skin’s biology; the impact of modern lifestyles; and how moisturisers work. If you’re not in the mood for in-depth science, the takeaway here is that taking care of your skin with a well formulated moisturiser will undoubtedly support your skin’s optimal functioning, and put you in the best possible position to avoid or minimise many skin concerns.

Moisturising supports the skin’s barrier function

What is your skin’s main function? As your largest organ, your skin has the honour of protecting our other organs from the outside world. It is our first line of defence against physical harm, biological infection, chemical absorption, and even weather. It houses nerve endings, hair follicles, and blood vessels that all help us navigate life on this planet. All these protective and transmissive functions happen in the uppermost layer of our epidermis (our stratum corneum), which forms a waterproof barrier.

In addition to protecting us, our skin also stops things from getting out!

Most importantly, our skin helps stop the water in our bodies from evaporating faster than we could replenish it. This is ultimately what sustains life on land, so it’s fair to say our skin is pretty special.

What is Transepidermal Water Loss?

The evaporation of water from your skin is called Transepidermal Water Loss (TEWL) and the rate of water loss (or the ‘barrier function’) is a commonly used scientific measure of how your skin is functioning. On average we lose 300-400ml of water from our skin daily!

Maintaining optimum water content in your skin is crucial for both the efficiency of your skin’s multiple practical functions and maintaining smooth and supple skin - which is why good barrier function is so essential. It’s the foundation of your skin’s function, feeling, and appearance. 

Water content in the stratum corneum is maintained by your skin’s NMF natural moisturising factor (a group of water soluble compounds) and intercellular lipids (your skin’s natural oils). It is generally accepted that although the structural integrity of your stratum corneum is provided by your skin cells (corneocyte), its other properties, such as water transportation, barrier function, and the ability to accommodate mechanical stress and relaxation, are regulated by the intercellular lipids. Both components need to be healthy and supported for your skin to be performing optimally.

What happens if your barrier is impaired?

If your barrier function has been impaired, the protective qualities of your skin tend to suffer in the long term.

Less than optimal dermal water content results in a decrease in the ‘plastic’ a.k.a. ‘soft’ and ‘supple’ properties of your skin, and an increase in its fragility and brittleness. This surface dehydration is the first step in the development of the dry skin cycle, in which drier skin loses water faster, and becomes dryer, and so on. Skin with impaired lipid barrier requires appropriate ongoing care.

How does moisturising help support the skin’s natural functions?

An important strategy in maintaining healthy skin - both in terms of structural integrity and appearance is the use of cosmetic products that increase the skin’s water content and replenish the skin’s lipids which can restore the normal functioning of the lipid barrier.

Cosmetic ingredients with these characteristics are called moisturisers. Application of moisturisers to the skin can therefore induce changes in its superficial as well as deep layers.

By making sure you’re moisturising properly you’re taking a proactive approach to your skin’s health and functionality, rather than waiting for problems to crop up - an ounce of prevention is better than a pound of cure after all! 

Your skin’s structure

Skin cells aren't bricks…

You may already be familiar with the frequently employed ‘brick wall’ analogy for describing the structure of the cells in your stratum corneum. In this analogy, the corneocytes (your skin cells) are the bricks, and they are surrounded by lipids (your skin’s natural oils) which form the mortar, filling the gaps and binding the bricks together. The neatness and solidity of this structure creates the barrier that gives your skin its integrity and helps reduce water loss.

Although this model still provides a reasonable metaphor for the structure of the stratum corneum and can be useful for graphic representation, it is vastly over simplified and does not do justice to the complex architecture of our skin. It is also slightly outdated.

In recent years the most cutting edge dermatological research views the skin not as a largely inert protective ‘wrapper’, but as being biochemically active.

It is now understood that there’s biochemical activity even in the upper layers of the dermis - e.g., the stratum corneum - which was previously dismissed as having only structural significance.

Skin cells are more like sponges

In the latest models, the ‘bricks’ of the old analogy are reconceptualised as keratin ‘sponges’ between lipid layers that are highly organised and tightly packed. These sponges contain your skin's natural moisturising factor (NMF) - a group of water soluble hygroscopic compounds which increase our skin’s ability to bind water molecules to these sponges. When our skin barrier is impaired, our NMF is more easily leached from our outermost skin cells by environmental changes and stressors e.g. wind, weather, and humidity. This reduces water retention in the stratum corneum, which in turn impacts the flexibility and ‘plumpness’ of our skin. Think of the look of a wet sponge vs a dry sponge and you’ll have the general idea. 

Water supports your skin’s elasticity

In addition to facilitating efficient hydration in the upper layers of the dermis, our skin’s NMF also appears to increase the elasticity of the stratum corneum. The water molecules act as a plasticiser, imparting an elastic property to your corneocyte (skin cell) proteins. When your skin cells are deprived of water, the corneocyte proteins become more brittle and the skin tends to be more vulnerable when subject to mechanical stress. On your body, for instance, this might happen when the skin has to stretch over a baby bump.

The water content of the skin influences its elasticity, and is essential to maintaining its suppleness and flexibility as it responds to various environmental and mechanical pressures over your lifetime.

It’s for this reason that dermatologists can be confident that improvements in your skin’s moisturization and hydration will lead to improvements in your skin’s condition. 

Oils support your skin’s resilience

What about the other part of the ‘brick wall’ analogy - the mortar? The mortar, a.k.a. the intercellular barrier lipids (including cholesterol, essential fatty acids and ceramides) work together to form a multi-layer barrier to help prevent transepidermal water loss (TEWL). By minimising TEWL, increasing hydration, and reinforcing the physical barrier, these lipids help maintain skin's natural collagen, elastin, and proteins.

Preserving the level of natural oils in your skin is therefore a crucial factor in supporting the resilience and flexibility of the stratum corneum, especially in instances where you know your skin is going to be under extreme levels of environmental or mechanical stress. 

What are the factors that impact barrier function?

Everyday factors

We don't live in a bubble.

Every day our skin can be exposed to things like UVA+B rays, wind, temperature changes, humidity, altitude changes, pollution, varying hydration and nutrition levels - which can all impact how the skin functions. Several everyday activities and encounters can impede the protective function of your barrier, and have a knock on impact on the optimal functioning of your skin’s normal activities.

Daily events like hot showers or cleansing can remove lipids (your skin's own natural oils) from the uppermost layer of your skin (your epidermis).

Unfortunately, whilst washing is absolutely essential, your cleanser can’t tell the difference between your essential fatty acids and the crucial lipids in your skin and the sebum, dirt, and residue you need to get rid of. Climate, altitude, and seasonal changes alter things like temperature and humidity, which can affect how easy it is for the skin to retain water, and therefore how well it functions. Air pollution exposes your skin to chemicals and physical particulates that can cause all kinds of problems and necessitate extra cleansing - which can be extra drying.

As part of its protective function, your epidermis is continuously adapting to these changes and challenges in environmental conditions.

This can lead to changes in the oil structure of the upper layer, which in turn can affect the quality of your skin’s barrier function - especially if the skin isn’t getting appropriate support.

In their function as a topical, supplementary barrier, moisturisers can also reduce your skin’s vulnerability to extreme or rapid changes by ‘buffering’ the skin against things like air conditioning or hot water. 

Stress and diet

Your skin can also face challenges that are less about your external environment and more about your physical state. Your diet, for instance, can have an impact if it’s not nutritionally dense, and healthily varied. Stress, which is an inescapable fact of life (especially these days), also has an impact; when our cortisol and adrenaline levels spike it impacts our skin’s collagen’s function. Conditions like rosacea and eczema can also be exacerbated by stress.

Hormonal changes

Most of us will have experienced the havoc hormonal changes can wreak on our skin’s behaviour, either during puberty or in response to birth control or pregnancy. Supporting the skin’s barrier function with moisturiser can help reduce acne caused by excess sebum production, or by bacteria and particles entering the dermis causing an infected ‘pimple’. It can also counter the dryness caused by over the counter anti-acne medication, and train the skin out of excess oil production if oiliness is the problem. 

Pregnancy

During pregnancy there is the added complication, indicated by recent research, that TEWL actually increases slightly during the gestation and post-natal periods. One study found significant lipid changes in the stratum corneum, which may be related to the fragile skin barrier of pregnant women. Although most skin changes subside after pregnancy, a weakening skin barrier during pregnancy does call for greater attention to skin care and careful product selection.

The components of a moisturiser

Occlusives

Most moisturisers and emollients have an occlusive effect in addition to delivering direct surface hydration.

This means that they form a semi-permeable protective layer on top of the skin, which reduces or inhibits transepidermal water loss (TEWL).

This helps increase the skin’s moisturisation indirectly. Vaseline (or any equivalent petroleum based product) is an example of a very strong occlusive. It does a great job of preventing water loss from your skin, but its texture and aesthetics don’t make it the most pleasant or practical to apply.  It is also very inert, and will only sit on top of your skin, without interacting with your lipid layers or attracting extra moisture. Petroleum products are also derived from fossil fuels which, as we all know, should be left in the ground.

Waxes and plant based oils are also occlusive. Depending on their fatty acid composition, however, plant based oils provide more than just occlusion; they can help replenish your lipid layers as well. And that’s not to mention the fact that they frequently have additional benefits for your skin, such as antioxidant properties. Plus they’re often more sustainable than petroleum based products.

Emollients

The word emollient is derived from the latin word meaning ‘to soften or soothe’.  Replacing the skin’s naturally occurring lipids with emollients also gives it a soft smooth feel. 

Sometimes either oils or the whole moisturiser is referred to as an emollient. Whether it’s a single ingredient or the whole product, you can think of it as the thing that makes your skin feel velvety soft and smooth. A good example of an emollient is squalane ,which mimics your skin’s own natural oils and provides a host of other benefits. Some ingredients double up as both occlusives and emollients.

Humectants

This is an ingredient that attracts water. They pull moisture from the air and add hydration to your skin.These are the ingredients that can give skin a plump, dewy, smooth look. Water based skincare are formulated with humectants not only for their hydrating qualities but they also help stabilise and affect the texture of a product. So you are likely to already be using products with humectants without realising it. This goes beyond skincare, your toothpaste is also packed with humectants to prevent the other ingredients from drying out.

Humectants should be used with occlusives (either together or after) to help seal the moisture in, otherwise all the moisture the humectant worked to bring to your stratum corneum will be evaporating into the air.

The most common and a very effective humectant is glycerin. Others include hyaluronic acid, Sodium PCA, Panthenol to name a few. These ingredients can have other benefits as well and don't strictly only function as a humectant alone

Other ‘active’ ingredients

In addition to acting as a barrier, moisturisers can also be a delivery system for other beneficial ingredients - either added to the moisturising product formula or applied separately as a serum. A couple of popular ingredients include vitamin C, hyaluronic acid, niacinamide, vitamin E, and other antioxidants. The idea is that these ‘actives’ will sink through the layers of the dermis as the skin absorbs the water from the moisturiser. Active delivery, however, is chemically complicated, and their inclusion in a formula requires careful calibration of percentages, delivery vehicle, and pH. 

The self-care benefits of moisturising

Moisturising also has benefits in a more holistic sense.

Whether you’re patting a rich cream into your face and neck or smoothing a beautiful oil over your body, the physical act of getting in touch with your skin is a wonderful form of self-care.

Physical affection is a great way of self soothing and reducing your overall stress levels. Indeed, one study has found that self-touch can be almost as effective a form of stress reduction as receiving a hug! There are also some studies that suggest the physical action of massage also be beneficial for the skin itself, but more research is needed before we can definitively make claims like that. But since we know self-touch is calming, and reducing your stress levels also increases your skin’s resilience from the inside out - what’s not to like?

The takeaway

Sometimes the simple, foundational, universal answer is the right one - and that’s certainly the case with moisturising. It’s an essential step for optimally functioning, naturally healthy skin. Luckily for us, moisturisers don’t have to be super expensive or packed with trending ingredients for them to be effective - they just need to be well-formulated. A good oil, lotion, or cream will be able to protect and smooth your skin effectively, and build its resilience and hydration levels long term. 

So, whether you’re worried about everyday environmental stressors; or you’re preparing for a big change in the challenges your skin will be facing (e.g. growing a new human), you should be moisturising!

Medical Disclaimer

Please note that this website does not provide medical advice. The material on this website are for informational purposes and not intended as a substitute for professional medical advice or treatment. As always seek the guidance of your doctor or other qualified health care provider with any questions you may have regarding your health. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.