Is It True That "Your Skin Gets Oily Because It Lacks Moisture"? Kazunosuke's 7 Secrets of Oily Skin Care

Kazunosuke has atopic skin, but says that from middle and high school through university, their T-zone was very oily and prone to acne. Even now, breakouts appear quickly if they eat poorly. Because their skin was partly oily, they researched oily skin care on their own and kept sharing what they learned. They say that some of what is commonly described as the basics of oily skin care actually traces back to their own posts.

The first principle is that you don't need to use milky lotions or creams. Kazunosuke says this was the subject of a video made within the first year of starting their YouTube channel, and it was widely viewed.

According to Kazunosuke, around the year 2000 a popular theory held that "people with oily skin produce sebum because they don't add oil in their skincare." At cosmetics counters and beauty salons, people who got oily easily were often told that their skin lacked oil and was dehydrated, so they must never skip lotions or creams.

However, Kazunosuke says there is "absolutely no" research or evidence showing that adding oil reduces sebum production. Back in university, when they were struggling with acne, they tested this theory directly using fats similar in composition to sebum. After one to two months, they saw no trend toward less sebum; if anything, their skin became somewhat irritated. They also felt that using oily products like lotions and creams made their skin shinier.

As Kazunosuke explains it, the amount of sebum your skin produces stays roughly constant whether you add oil or not. Layering lotions and creams on skin that is already oily simply increases the oil that causes shine and acne, raising the risk of breakouts.

They also touched on differences between types of oil. Fats with a triglyceride structure break down on the skin and tend to cause acne. Squalane and ester-type ingredients, on the other hand, break down less easily and are relatively less likely to cause acne. But telling whether something is a fat, an ester, or a hydrocarbon oil is difficult for the average person without in-depth chemistry training. Kazunosuke's view is therefore that it is safest to avoid products containing oil altogether.

Moisturizing, they say, can be done with water-based products that contain little oil, centered on toner, along with serums and gel-type products. People with oily skin already produce plenty of their own sebum, so there is little need to add oil from outside. Kazunosuke's view is that your own oil plus water applied externally strikes the right balance. They say a previous video drew many comments from people whose problems improved dramatically just by stopping lotions and creams.

Kazunosuke considers cleansing extremely important in oily skin care. In their ingredient analyses, they find it hard to give high ratings to cleansers that are strong and irritating, such as soap-based cleansers and cleansers made with powerful synthetic surfactants. They say people with oily skin often see those ratings and end up choosing gentle, mild amino acid–based cleansers.

But oily skin has a lot of surface oil, and mild cleansers can't remove it adequately. Following online ratings as-is can lead to insufficient cleansing and actually make things worse. Kazunosuke therefore recommends soap-based cleansers as a safe choice. They are strong but well suited to cleansing oily skin, and they have the added advantage that any residue is unlikely to cause itching.

On the other hand, Kazunosuke points out that intermediate cleansers—slightly less powerful than soap with a milder feel—are almost nonexistent on the Japanese market. Because cleansers fall into two extremes, "strong cleansing" and "very gentle," people with "oily sensitive skin," meaning skin that is both sensitive and oily, are left in a bind. As products with intermediate cleansing power, they also mentioned the cleanser from their own brand, Ceralabo, as well as a past video rounding up cleansers.

If you want to use a mild cleanser, or have already bought one, they recommend pairing it with a makeup remover. Even men and teenagers who don't wear makeup can use one. Without makeup, there's no need for a powerful remover; a mild ester-based one that rinses clean, like MUJI's product, is enough. The routine is to remove oil with the cleansing product and then wash away remaining dirt with the amino acid cleanser. Kazunosuke believes that trying to remove oily grime such as clogged pores with a cleanser alone puts more strain on the skin, and that this double cleanse is gentler.

This is the only one of the seven about diet. Kazunosuke explains that various studies have shown that much of the fat that comes out as sebum is fat from the food you eat. When they previously researched the evidence on foods that worsen acne for a video, they reached the conclusion that it's fair to say the oil you eat effectively comes out as sebum. Bad fats tend to induce inflammation, causing inflammation inside pores and leading to acne, so they say you should avoid eating them.

Kazunosuke names trans fatty acids as the worst. They describe these as a general term for fats that are banned or regulated in countries around the world and whose harmful health effects are clearly shown by evidence. They do not exist in this form in nature and are created when cooking oils undergo a chemical process called partial hydrogenation to extend shelf life. Japan has no regulations on them, and Kazunosuke criticized the Ministry of Agriculture, Forestry and Fisheries for not regulating them based on the wishful thinking that "Japanese diets don't contain that much, so it's probably fine." Trans fats are used in snacks, hot convenience-store foods, fast food and the like, and most of the fats in snacks sold at supermarkets are said to be trans fats, according to Kazunosuke.

As label names, they listed shortening, vegetable oil and fat, and margarine. "Vegetable oil and fat" is a catch-all label covering both natural oils and hydrogenated oils, so some speculate that it is used to obscure unhealthy fats. Some margarines are low in trans fats, but since you can't tell from the label, they say the only option is to avoid them across the board.

Next to avoid are saturated fatty acids. Fats that solidify, such as butter and coconut oil, are said not to be good oils. They're better than trans fats, but they're used heavily in cakes, cookies and the like, so it's best to limit them as much as possible. They also said that while milk can't be called a bad fat, some people's constitutions don't agree with it and it makes them more prone to acne, so they don't really recommend milk either.

Conversely, there are research findings that the more fish oil you consume the better, and studies showing that acne improved the more fish people ate. They therefore recommend raw fish such as sashimi and sushi. Among cooking oils, rapeseed oil and salad oil are said to be not very good, while olive oil, rice bran oil and sesame oil are said to be good for the body. They advise limiting fried foods, and choosing these oils if you do eat them.

This may sound like it contradicts Secret 2, but Kazunosuke explains that Secret 2 is about evening cleansing, while this one is about morning cleansing.

As the basis, they cited research findings that when sebum is removed (degreasing), sebum production increases to quickly replace what was lost. Adding oil doesn't change sebum levels, but excessively removing your own sebum increases them. In data Kazunosuke presented, skin excessively degreased with acetone returned to normal sebum levels in about two hours, recovering to roughly the same amount as 24 hours earlier. In other words, the skin produces 24 hours' worth of sebum in two hours.

Washing twice a day, morning and evening, is recommended for people with oily skin, and Kazunosuke also recommends this in itself. However, if you degrease as strongly in the morning as at night, sebum is released all at once during the morning, and you tend to become shiny right when you're meeting people at school or work. If you wash thoroughly at night, the sebum you removed is replenished overnight. If you wash in the morning in a way that leaves some of that sebum, the skin judges that oil remains and doesn't produce as much. That's why an amino acid cleanser is fine in the morning, they say.

According to Kazunosuke, past research has shown that when you stay indoors, sebum produced while you sleep barely oxidizes. Morning sebum is fresh, so there's no need to force it off. If your skin is sensitive, washing with lukewarm water alone is enough, and people with oily skin who find that difficult can lightly remove surface oil with a gentle cleanser such as an amino acid–based one. Kazunosuke recalls noticing this finding in university and putting it into practice, and says their daytime sebum production didn't increase at all and their skin was in good condition.

This is a theme covered many times in past videos. According to Kazunosuke's explanation, there is a study in which a cosmetics manufacturer, while examining base ingredients for cosmetics, tested their "assimilability" by C. acnes, the bacterium that causes acne. Assimilability refers to a bacterium's ability to use an ingredient as food to multiply. When water-based moisturizing ingredients and polyhydric alcohol ingredients such as ethanol, BG, glycerin and diglycerin were compared, only glycerin increased C. acnes. It caused a big stir in the industry at the time, but because it was considered problematic on various fronts, the data is no longer publicly available, they say.

Kazunosuke says the result makes sense to them. Glycerin is a moisturizing component naturally present in human skin; when triglycerides, the main component of sebum, break down, they become three fatty acids and glycerin. It wouldn't be surprising for resident bacteria to multiply by feeding on moisturizing components on the skin's surface.

They also noted the counterargument that since glycerin is naturally present in skin, it's unlikely to be a cause. In response, Kazunosuke suggests that because people with oily skin produce more sebum, they may also have more glycerin from its breakdown than others. Balance is important for skin, and it's quite conceivable that an excess of a particular ingredient could upset that balance and lead to breakouts, they say.

However, Kazunosuke themself admits that it's unknown whether glycerin is truly the cause and that evidence is lacking. It's positioned as not a conclusive basis, but worth trying. Comments include a great many reports that it worked. They added that because people who succeeded are more likely to comment, there's a bias, so it can't be declared the cause. Still, some people are so convinced of its effectiveness that they won't use anything that isn't glycerin-free. The conclusion is that there's no downside to trying, so the potential value is significant.

They also raised a point unrelated to acne. Although glycerin isn't an oil, it refracts light in a distinctive way that gives a shiny look. Kazunosuke says they have felt in the past that applying it around pores makes pores look more noticeable. It doesn't make pores worse, but it may be worth trying for people concerned about their pores as well.

Kazunosuke prefaces this by saying they won't claim these will definitely work, since you can't know which ingredient suits you until you try it. With that in mind, they explained that there are only two or three cosmetic ingredients in total with clearly recognized sebum-suppressing effects.

The first is Rice Power No.6. It's a separate active ingredient developed by the manufacturer known for Rice Power No.11+, and its sebum-suppressing effect is recognized under Japan's quasi-drug category. However, few products contain it—ONE BY KOSÉ and a handful of others. Some products also contain alcohol, so it may not suit every skin type, they say.

The second is pyridoxine hydrochloride, whose sebum-suppressing effect is likewise recognized as a quasi-drug. It's in Melano CC's premium serum, but they say it's rarely seen elsewhere. That product also contains ascorbic acid (vitamin C) as a second active ingredient. Vitamin C is also said to have evidence for sebum suppression, so that effect may be expected too. Personally, though, Kazunosuke says they haven't really felt vitamin C significantly reduce sebum. They say derivatives such as tetrahexyldecyl ascorbate and 3-O-ethyl ascorbic acid may have felt more effective.

Third, they named azelaic acid. Pharmaceutical-grade versions are the most potent, but they say Rohto Pharmaceutical recently made a dissolved-type serum as a cosmetic. It's a 3% dissolved formula and reportedly achieved effects equivalent to a 15% cream. That data relates to acne, but they say they also heard it may have outperformed the cream in sebum suppression. The derivative potassium azeloyl diglycinate has gentler effects but can be used relatively mildly, and the raw material manufacturer's documentation recognizes its sebum-suppressing effect. There are also reviews saying derivative-based serums reduced sebum, they say.

However, all of these ingredients act inside the skin, so there's a risk of strong irritation or incompatibility. Kazunosuke cautions viewers to try them carefully.

Kazunosuke considers this quite important. They say they've received many comments from people who felt their sebum dropped significantly after stopping irritating skin care they'd been using regularly.

Kazunosuke gave two reasons. One is that inflamed or irritated skin tends to produce more sebum. Because sebum plays a role in protecting the skin, stinging irritation or inflammation makes it come out more readily. That's also why skin tends to get shiny when you have lots of acne, they say. The other is that sebaceous glands tend to become more active in response to physical stimulation.

As specific examples, they cited vigorous rubbing, scrub cleansers and peels, saying all of these raise concerns about increasing sebum over the long term. The same goes for skin care that doesn't cause breakouts but stings, containing irritants such as alcohol. Because the skin is resilient, it doesn't become inflamed, but it still senses the irritation, which can cause sebum production, they say.

Describing a pattern especially common in men with oily skin, Kazunosuke says the following. People whose skin doesn't break out but produces large amounts of sebum often have sloppy routines or use products that actually don't suit their skin. Their skin simply doesn't break out because it's resilient. Men's skin care often contains a lot of alcohol and tends to be irritating, with a cooling tingle that nobody really asks for. Some people report that their sebum improved just by switching to an ordinary product for sensitive skin. Kazunosuke's personal view is that quite a lot of people might improve simply by stopping irritation.

They also recommend ceramide-based skin care, since it strengthens the barrier function, eases irritation, and can sometimes lower sebum production. Some argue that ceramides are lipids and therefore unsuitable for oily skin. But according to Kazunosuke, ceramides are expensive and included only in tiny amounts—0.1% or even less—so they almost never cause clogged pores. That said, many ceramide products have an oily feel like lotions and creams, or are made for dry skin with added glycerin, so they may not suit oily skin because of ingredients other than ceramides. They mentioned that their own brand makes glycerin-free, oil-free ceramide products.

Kazunosuke said there are still other kinds of care they'd like to recommend for oily skin, such as using makeup and face powder, and that they'd like to make a second installment if the opportunity arises. They closed the video by saying that nearly all of the content can be tried by teenagers and young people of any gender, and that quite a few people might see their problems improve just by trying these seven.