If you’re asking/shouting – heck what are the causes of oily skin. Will someone just tell me how to get balanced skin that doesn’t look greasy or oily anymore. You need to read this blog now.

8 Causes of Oily Skin Plus How to Reverse Them

In Oily/Combination Skincare Advice by Cheryl Woodman MChemLeave a Comment

Fed up with your skin looking greasy and shiny? I hear you my friend and I get this first hand. My skin used to be so oily that makeup would literally ‘sweat’ out of my skin within hours of putting it on.

I remember being sat in corporate work meetings feeling like all everyone could see of me was the oil slick on my face.

In my mind, I was scream thinking, why? why!? What the heck is causing my oily skin? Why does my face produce so much oil? And what can I do to fix it?

Please, someone, give me the answers 🙏

I so wish I had this blog you’re about to read back then.

While I can’t promise what you’re about to find out will get rid of your oily face causes – I do know they have maximum scientific potential to help. And I know some of these are key for me – number 2 and 4 in particular.

So, let’s get you started shall we? Come get your eyes on these 8 causes of oily skin and what to do about them. Wahoo.

If you’re asking/shouting – heck what are the causes of oily skin. Will someone just tell me how to get balanced skin that doesn’t look greasy or oily anymore. You need to read this blog now.

Psst – please keep in mind as you read this blog, it’s likely the cause of your oily skin is not down to just one of these reasons. Instead, it’s extremely likely to be a combination of factors – if you would like my help in identifying yours and to finally get the balanced, happy, glowy (but not shiny or greasy) skin you want – then know I’m here to help.

1. Vitamin D Deficiency

Oooeee eh. I know this probably sounds ridiculously surreal as a starting cause of oily skin. Well… unless you caught my blog a few weeks ago on – does sun help acne? If you got a good read of those 5 reasons why the sun can help prevent breakouts then you’re already super savvy on this key reason for oily skin.

Because, here’s the deal. 

Vitamin D is a hormone.

Wowser eh – I bet you thought only sex hormones were responsible for oily skin. I once did too (!)

And here’s the important fact. Vitamin D helps to regulate sebum production.

Lookee at this;

Vitamin D seems to inhibit sebocyte proliferation, differentiation, and sebum secretion, all of which are key factors in the production of sebum.Dermatoendocrinol. 2014 Jan-Dec; 6(1): e983687

Psst – sebocytes are the cells that make sebum and all this scientific study is telling us is that vitamin D can help reduce sebum production.

Exciting eh.


What are the causes of oily skin? Vitamin D deficiency can be a key cause of oily skin. Balance your vitamin D levels and you could get the healthy balanced, glowy skin you want.

2. Insulin Provoking Foods

If you’ve identified hormones as a cause of oily skin, you are 100% on the right track my friend. But where most people go wrong is they think it’s sex hormones that have the biggest impact. 

And that therefore there’s not really anything that can be done other than to fill up your makeup bag with blotting papers, mattifying face powders and hope that it settles down at some point when you’re older – but heck, you’re an adult now so when will that be!?

This insulin thing my friend is a powerful hormone.

It gets released every time you eat. And when it’s released it comes along with its soulmate.

And just like all soulmates, this dude has a cutesy nickname 😉

But it’s not babe, or boo or honey bun.

It’s IGF-1 😉

Aka insulin-like growth factor.

It’s a growth hormone.

And here’s the deal, when you’re wondering why is my skin so oily all of a sudden – it’s super likely something’s hyper-stimulating your sebum glands aka your skin’s oil-making cells.

IGF-1 does this.

What are the causes of oily skin? A diet high in insulin stimulating foods. Yes, sugar is one of them but there are so many health foods that do this too. The simplest way to start acting on this cause of oily skin is to remove refined carbs from your diet. When you enroll in SkinCoach with me I’m going to ask you to complete a one-week food tracker so I can walk you through how to do this step by step.

3. Heat

Or plainly the fact that it’s summertime. Yay. Coming from the UK I get so excited to see the sunshine. Even though I know it can be an oily face cause, I’m sun dancing all winter long.

Take a peek at this;

…sebum excretion rate varies directly with temperature, so that an increase in temperature of 1°C produces an increase in the sebum excretion rate in the order of 10%.Skin Pharmacol Physiol. 2012;25(5):227-35

So for every one degree, we go up in temperature your skin might look 10% more oily. Crazy eh.


The even crazier fact is this – your skin looking oilier in summer does not necessarily mean your skin’s making more oil. This very same study goes on to explain how heat can thin sebum and therefore make it flow out from your pores quicker.

So heat being an oily face cause is actually your sebum becoming quicker flowing.

Like when you make custard. It’s thin and easy pouring when you make it hot, but when it cools down your custards getting thick and gloopy. The thick stuff needs cutting out of the custard jug 😉 the thin, hot stuff is running freely on top of your apple crumble. Delish.

What are the causes of oily skin? Heat can make your skin look extra oily and greasy. You can help to control this with the right skincare and I’m speaking more about this soon.

4. Essential Fatty Acid Deficiency

I hope you can see by now this is not a normal list of reasons for oily skin eh. If you’ve been searching for causes of oily skin I bet you’ve stumbled over answers like;

  • Genetics
  • Sex hormones
  • Enlarged pores
  • Skipping moisturiser
  • Stripping your skin of natural oils/using drying skincare which only makes your skin oilier – psst – this is actually a science proven myth

I bet you’ve not heard of causes of oily skin like essential fatty acid deficiency.

So what the heck does this mean eh?

Here are the facts your need to know – your beautiful body, even though it’s completely wonderful, can’t make certain oils and these get nicknamed essential.

You have to get them from your diet. Or your skincare.

And your skin health will plummet without them.

Here’s the spoiler – there’s evidence to show certain inflammatory signalling molecules our skin uses can also trigger your skin to make more sebum.

Essential fatty acids are anti-inflammatory and have been specifically shown to help reduce this specific inflammatory signalling molecule (it’s got a mouthful of a name – leukotriene B4).


What are the causes of oily skin? Your body might be screaming – help – I’m deficient and I need you to feed me some essential fatty acids now. Psst – be careful if you supplement as the ratio of essential fatty acids matters a lot.

5. Keto Based Diets

Specifically, because they tend to mean you’re eating a mountain of calories per day.

Now don’t get me wrong, I firmly believe all calories are not equal and I strongly believe from a scientific point of view that calorie counting to lose weight is not a long-term solution.

Instead, it’s about how your body interacts with what those calories are.

It’s like speaking to your best bud in the whole entire world for an hour or being sprung into a surprise work presentation. Both mean you’re talking to people but one of these situations is going to make your heartbeat like butterfly wings and the other is going to make you chill, calm and super contented.

The reason why keto diets can be a key oily face cause is that they usually contain a mountain of calories – and this makes your body go – oooeee, I’m safe, I have a load of fuel, let’s grow – and that includes sebum glands too.

Psst – it’s the mTORC-1 pathway in your body that’s specifically linked with this messaging. But don’t worry about knowing this fancy name. All you need to remember is that diet is super important in controlling oily skin.

What are the causes of oily skin? Eating an unbalanced diet which pushes your body into a state of overnutrition where it grows, grows, grows like Jack’s beanstalk.

6. You’re Using The Wrong Skincare

As a cause of oily skin, this is one of the simplest to correct – especially if you have me in your corner 😉

Now there are so, so many ways the wrong skincare can be a cause of oily skin – but this is the one I see most often.

Using inappropriate moisturisers in your morning skincare routine. These will have your skin looking greasy within hours of putting makeup on. Sometimes even quicker.

And that’s because in the morning your sebum glands are programmed to pump out oil. It’s like they just had their morning coffee and are ready and raring to go, go, go.

Psst – your sebum glands are programmed this way because they have what are called clock cells. Crazy eh. They can literally read the time of day by how much light they’re absorbing.

And this means your skin gets oilier towards midday. And then your skin’s oil production reduces in the afternoon.

So if you’re using a moisturiser that can become greasy when it’s mixed with sebum – your skin will look super oily within hours of your morning routine.

What are the causes of oily skin? Using the wrong skincare, especially in your morning skincare routine when skin’s programmed to ‘pump, pump, pump it out’. Get your morning skincare routine right and your skin will look a heck load less oily.

7. Your Skin’s Making Excess Androgens

You said what!? My skin is making hormones?

A lot of people are completely unaware of this.

Now you’re not my friend.

There are specific enzymes that live in your skin – do you remember from biology class how these are like keys that turn locks? And that when they turn the lock these enzymes make things happen – like a door opening?

Well, your skin has a very specific enzyme called 5-alpha-reductase.

If you’ve been wondering what causes oily face this could be your missing link.

Because this ‘key’ converts testosterone into another hormone that’s 5-10 times more potent.

It goes by the name of dihydrotestosterone or DHT for short.

Take a peek at the study quote I’ve lifted for you below.

…sebum production can be increased by overproduction of androgens in the pilosebaceous units due to enhanced expression and activity of androgenic enzymes…Dermatoendocrinol. 2009 Mar-Apr; 1(2): 81–86

Psst – don’t worry if it sounds super sciencey, all this quote is telling us is that certain skin types might have more of this enzyme which ‘fertilizes’ the super androgen.

And because androgens cause your skin to make oil – boom – you get really oily skin.

What are the causes of oily skin? Your skin might have a lot of androgen-making enzymes. Don’t worry – certain skincare contains actives that can help to turn down their volume. I’ll be including these in your skincare routine.

8. You’re not exercising enough

Okay so this final key reason, it’s actually linked with number two. Do you remember that one? When we talked about insulin-provoking foods?

This one is a domino train.

Because lack of exercise means your body needs and therefore releases more insulin.

Lack of exercise = more insulin = more insulin-like growth factor = a cause of oily skin.

It’s like if you try to wake up at 7 am in winter vs. 7 am in summertime.

In the summertime, your body has sunlight to naturally say – howdy, it’s time to get up :D.

In wintertime, at 7 in the morning, it’s pitch dark outside and so your body struggles to wake up naturally. No light means it’s sleepy time still.

Exercise is like summertime to your body, because it naturally helps your body absorb energy without the need for as much insulin. Yay.

And just like that, we help reverse the oily skin domino train.

Exercise = your body needs less insulin = less IGF-1 = less sebum. Wahoo.

What are the causes of oily skin? Lack of movement and day-to-day exercise. If you have an office job, it could be very likely your body needs more. It definitely doesn’t have to be anything super strenuous, something simple like walking with weights or a short yoga class can be fab.

Wahoo, you’ve made it my friend. You now know 8 key causes of oily skin. Which do you suspect to be your trigger combination? Let me know in the comments below. 

Oh and if you have a friend you know would love help with her oily skin, will you forward her this blog with my love? You are the best 😀