What is that rumor that oil can't hydrate your skin or hair?

Much has been said about the properties and benefits of oils for your skin and hair, but could that be a myth?

We've all heard the properties of jojoba oil, coconut oil, grapeseed oil, rosehip oil, and what have you, but this rumor has me wondering whether it is yet another marketing trick. 

Several words are used to market beauty products, they sound good, but do they really mean anything at all? What do clean beauty, nourishing, refreshing, and many other words that are paired with skincare and haircare products really mean? 

Many oils also clam to have hydrating properties, but is that so? Oil, by definition, has no water, it is actually hydrophobic, meaning that it does not attract water, it actually repels it, so what happens with oils in the beauty industry?

Is it a rumor that oils hydrate?

In short, yes, it's a rumor. Oils cannot hydrate, they cannot add any water, they help moisturize. Oils can condition skin and hair and retain water content so it does not evaporate, then they moisturize, not hydrate.

Oils are great at creating an occlusive barrier over a humectant to make it harder for water to evaporate and eventually cause your skin and hair to become drier. So, while they are not technically hydrating, they play a key role in the moisturization process. So it does not mean that you cannot use any oils for your hair or skin, in fact, they have several benefits, but you should always pair them with other products that do add water to your skin.