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Mythbuster: Why Face Oils Do Not Hydrate Your Skin

Are you relying on a facial oil (like rose hip or jojoba oil) as the core element of your natural skincare routine? Or is it even the only product you use to moisturise and hydrate your skin? You feel confident that you are giving your skin enough because it feels so very soft and supple straight after the first use – that must be good, right?

It is very common to find body oils, face oils and even shower and bath oils claiming to hydrate. But the truth is, oils do not and cannot hydrate your skin. In fact, when used incorrectly, they can even dehydrate your skin.

Why Oils Don’t Hydrate

Thinking back to year 10 chemistry you’ll remember that the word ‘hydrate’ relates to water. Hydration technically refers to the binding of water molecules to another element. To hydrate simply means to add or to absorb water.

Hydrated skin means that your skin cells are holding a healthy level of water. Dehydrated skin on the other hand refers to water levels in your skin being lower than what they should be. When your skin is dehydrated it will appear sunken, tired and dull. With a healthy level of water in your skin, it will appear bright, bouncy and plump.

Oil of course, is not water. Oils are what we call ‘emollients’ in skin care formulation. They are designed to soothe and soften dry, flaky skin to make it look and feel better. Adding oil to your skin is not able to increase its water levels, aka hydration. Only ‘humectants’ can do this – ingredients that have the ability to attract water, deliver it deep through the skin layers and bind it to where your skin cells need it. Oils can’t do this. On the contrary – they have an ‘occlusive’ capacity by creating a physical barrier that helps to trap any existing moisture in the skin. Because of this, they help to prevent transepidermal water loss. And that is where the confusion about using oils to hydrate might have started.

What is Transepidermal Water Loss?

Water is an escape artist – it doesn’t stay put. Transepidermal water loss refers to the process where water passively evaporates out of our skin (not talking about sweating here). On average our skin loses about 300–400 mL of water every day. During hot and humid conditions like our Australian summer, less water evaporates from our skin, as the outside water vapour pressure gradient triggering it is lower. In drier times like winter, this gradient goes up and hence our transepidermal water loss will be more significant – the escape artist at work. More water will evaporate from our skin, and it will feel drier and look flakier.

So Where Do Oils Come In?

Remember that oils have an occlusive, skin barrier protecting function. Oils and oil-based skincare products contain lipids, similar to our skin’s natural fats. These fats act as a protective barrier and in doing so promote moisture retention in the skin.

To put it into a picture, imagine lipids as the mortar that fills the gaps between the ‘bricks’ that make up our skin. This action creates a seal or barrier that prevents water escaping or evaporating.

Environmental factors like the weather, humidity, even hot showers can disrupt this barrier function. Certain skin conditions and even the normal aging process can increase the gaps between the bricks of our skin, allowing for accelerated transepidermal water loss. This is what leads to that scaly dry winter skin that many people suffer with in dry weather.

Applying oils rich in lipids (like jojoba oil) can help preserve the skin barrier function. This will fill these gaps and help the skin to lose less water than it normally would. Face Oils can also soften your skin, giving you the illusion of being hydrated. But adding water to the skin is something that even the best oils definitely cannot do.

The Best Way to Hydrate Your Skin

Before we can focus on keeping water in the skin, we need to get more water into our skin in the first place. The process of hydrating your skin most importantly starts from the inside with drinking enough water, every day. Aim for at least 8 glasses of water a day and your skin should be hydrated and stay hydrated. As a general rule, if you have a healthy skin barrier, drinking a generous amount of water is the most important step to keep yourself and your skin hydrated. Read that again.

Add to that day & night natural skin care products that contain water and also water-attracting humectants. These work by attracting water from the air and from the product itself to draw moisture deep into the skin, which will hydrate your skin cells.

Whilst lab-made hyaluronic acid attracts an impressive 1000 times its weight in water, you might not want to use such synthetic ingredients on your skin. Focus on serums and moisturisers containing natural humectants such as aloe vera, intensely hydrating rose oil, vegetable-based glycerine, or honey.

The best natural moisturisers combine active ingredients with emollients (softening agents), natural humectants to attract and add water, and natural occlusives (like oils) that help to create a barrier to keep moisture inside your skin cells.

If you suffer from eczema or other skin conditions, your skin’s barrier function is extra-compromised and you will be even more prone to water loss. Specialised natural skincare products can provide extra support to help restore your skin’s barrier function.

How Oils Can Dehydrate Your Skin

Rather than hydrating your skin, it has been suggested that oils can even prevent hydration. The order of events matters: If you were to apply an oil before applying a product containing humectants, you might unknowingly make it hard or even impossible for the humectant and water it attracts to pass through the oil layer all the way down to the lower layers of your skin, where we need it to get to work. This is especially true if you are using a moisturiser containing (synthetic) hyaluronic acid.

This is why the order in which you apply skincare is important. Always apply your serum first, and pure oils or lipid-rich products last in your routine.

In A Nutshell: Best Practise Skin Hydration

  • Do not rely on face oils to keep you moisturised. Even the best face oil cannot replace moisturiser – it is not able to add water to your skin.
  • The best way to hydrate your skin is not through a product, but from within. Ensure you’re drinking enough water and your skin should be and stay hydrated.
  • Twice a day use a powerful natural moisturiser that combines softening, hydrating and protective agents with other active ingredients (like antioxidants).
  • The order in which you apply skincare matters. Always apply your serum first, and pure oils or lipid-rich products last in your routine.
  • In extra dry and low humidity conditions ad oils or oil-based skincare products to your routine to prevent additional water loss through the skin.

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