What's the difference between moisturizing and hydrating your skin?

Moisturizing: Hydrating, Emollient, & Occlusive Ingredients

Published on March 9, 2021

Moisturizing is one of the most muddied terms in all of skincare.

Why?

Because you can enhance your skin’s ability to retain water using both humectants/hydrating ingredients (water soluble ingredients) and oils (ingredients that won't dissolve in water).

And, the idea that an oil can be moisturizing (restore moisture/hydration/water to the skin) just seems odd.

Let’s break down the ways that you can moisturize your skin:

Humectants/Hydrating Ingredients: Humectants are water loving ingredients that draw water into the skin.

Examples of these are:
- hyaluronic acid
- panthenol (provitamin B5)
- glycerin
- sodium PCA (this one might sound scary, but sodium PCA is a naturally occurring compound in your skin that helps maintain healthy levels of water within your skin).
  
  Humectants hydrate your skin because they're water loving molecules that help attract water to your skin from the environment.
Emollients: Emollients are oils and oil soluble ingredients, like ceramides, that help repair the skin’s natural moisture barrier (helping to keep water locked within your skin).
Occlusives: Occlusives are oils, butters, and even some water loving ingredients like hyaluronic acid that help form a film on the surface of skin preventing trans epidermal water loss (TEWL).

Occlusives are a powerful way to keep water locked within your skin, and these are especially welcome ingredients in your skincare routine during the wintertime.

Specific examples of these are shea butter, tamanu oil, olive oil, & high molecular weight hyaluronic acid.

You probably noticed that some ingredients can belong to more than one group.

Oils can exhibit more emollient properties or more occlusive properties depending on their composition.

Hyaluronic acid can work to pull water into your skin or form a film at skin's surface to prevent trans epidermal water loss (TEWL) depending on its molecular weight.

Brief side note on hyaluronic acid and molecular weight: hyaluronic acid is a naturally occurring compound in your body. It's a polymer, which means it's made up of a linked chain of repeating disaccharides (sugars).

Those disaccharide units are shown in the schematic below, and "n" represents the number of repeating units... so, n could be 1 or 1,000,000. The lower n is, the lower/shorter the molecular weight chain.

structure of hyaluronic acid

At low molecular weight (short chains of linked disaccharides), it more readily soaks into your skin and because it's hygroscopic (water loving), it pulls water along with it as it soaks into your skin.

At high molecular weight (long chains of linked disacharides), hyaluronic acid sits on your skin forming a film layer and preventing water loss.

A cool way to think about high and low molecular weight chains... you can imagine high molecular weight hyaluronic acid is a tree trunk... the whole thing. And, a low molecular weight hyaluronic acid is like small logs cut from the tree trunk.

While the entire tree is too big to fit in your house, you can bring the small logs inside. It's the same way with high and low molecular weight hyaluronic acid. High molecular weight HA is like the whole tree trunk, it's not fitting through the skin's outer layer to make its way inside while the low molecular weight HA is like the cut up logs... small enough to soak through the skin's outer layers.

Now, back to the article...

Which is the best moisturizer (Humectant, Emollient, or Occlusive)?

You most often want a product containing all 3 of these (humectants, emollients, & occlusives) in your daily moisturizer.

The universal day & night time lotion offered in Rain Organica’s Essentials Collection combines ingredients across these three categories:

Humectants: hyaluronic acid, panthenol (provitamin B5), aloe, glycerin
Emollients: hemp seed oil, meadowfoam seed oil, olive oil
Occlusives: hyaluronic acid, meadowfoam seed oil, olive oil

and is specifically formulated to meet a many of your skin's needs to help you reduce the number of products you need in your skincare routine.

If you can't wait for the next post in this series, download your free guide to simple skincare in just 3 steps.

About the Author

Brandy's a formulation scientist and self-proclaimed health geek who loves hiking, gardening, bird-watching, and body boarding.

Her struggle with acne during her teens and 20s led to a holistic and healthy approach to skincare, embracing skin as an organ to be loved and cared for rather than a canvas to wage war on.

Since 2008, she's been developing all-in-one products for a simple routine at home, & Rain Organica started when her backpacking friends asked for a portable skincare routine to keep their skin healthy & happy on and off the trails.

You can try Rain Organica for yourself with The Essentials Kit, a complete skincare routine in just 3 steps.

Brandy's LinkedIn Bio

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