Hydration and moisturizing! 90% of people fail this introductory course

Review expert: Zhang Yuhong, chief physician of the Department of Dermatology, Zhengzhou Central Hospital Affiliated to Zhengzhou University

Moisturizing is a must for every skin care girl. People's skin is very fragile and is prone to dryness and peeling during the change of seasons. In the cold winter, if you don't take some protection, your skin will even crack, and your face will feel painful and itchy. In the 1970s, when supplies were scarce, being able to use a can of "snow cream" was a sign of a sophisticated woman.

Source: Baidu Encyclopedia

Over time, until today, at the very beginning, the first bottle of skin care product that mother gave to each girl was a bottle of refreshing "toner".

Later, as they get older and their skin needs increase, girls start to learn to upgrade their skin care products. Skin care products have evolved from a bottle of moisturizing water to toner, lotion, essence, and cream. However, does the skin really need so much water? What is the deep reason why skin care products replenish the skin?

Oily skin? Dry skin? Combination skin?

Oily skin is also called greasy skin . The main reason is excessive oil secretion on the skin. It mostly exists in young people and obese people. The manifestation of oily skin is that the skin pores are larger, and the forehead, nose and other places are shiny. After washing the face for a certain period of time, the forehead, cheeks, nose, chin and other places can be clearly seen and felt. After applying too much skin care products, oily skin will develop acne on the face due to the abundant nutrients.

The underlying reason for oily skin is the vigorous metabolism of the skin itself, so oily skin can easily lead to enlarged pores on the face. Oily skin should be cleaned in time after applying foundation and other cosmetics, otherwise it will clog the pores and the skin will be "stuffy" and more acne will appear.

Source: pixabay

Dry skin is caused by less sebum secretion . Its external manifestation is that the skin is more delicate and the pores are not obvious, but it is relatively sensitive to external stimuli. If you do not apply any skin care products within a certain period of time after washing your face, your face will feel tight. After applying toner and other products, the tightness disappears.

Combination skin, as the name suggests, is a mixture of oily and dry skin. Generally speaking, within a certain period of time after washing your face, your cheeks and chin feel tight, but the forehead and the "T-zone" of your nose produce more oil, showing the phenomenon of combination skin.

The specific skin type can be simply judged by the above method. For further judgment, you can go to a professional medical institution for diagnosis.

Dry skin needs to be hydrated because the external manifestation of dry skin is tight skin caused by lack of water. Oily skin is caused by deep lack of water in the skin and imbalance of water and oil in the skin. Due to lack of water in the skin, the skin will secrete oil to protect the skin, thus forming oily skin with oily outside and dry inside. Therefore, dry skin needs hydration just like oily skin.

How skin loses moisture

In the article "The Truth About Skin Moisture Loss", author Qian Yangchun mentioned: Healthy skin has biological elements that can store water. In the stratum corneum of the skin, the oil substances between cells form a protective layer to control water evaporation, making it easy to retain water. At the same time, these sebum membranes, stratum corneum, and natural moisturizing factors in the stratum corneum can prevent the skin from drying out due to water loss, and also reduce the damage to the skin from various harmful factors in the environment.

However, the moisture of the skin is very easy to lose. The residual stains of facial cleanser left on the face after washing will absorb the moisture on the face. Wind, sand, weather factors, chemicals, etc. can also destroy the defense ability of the skin's own protective layer.

Source: pexels

Our skin can be roughly divided into three layers: epidermis, dermis, and subcutaneous tissue . Among them, the epidermis is the most direct contact between the human body and the outside world, and plays the most basic and important defense function. Subcutaneous tissue is the loose connective tissue and fat tissue below the skin, including blood vessels, lymphatic vessels, nerves, sweat glands, etc., connecting the skin and muscles, between the skin and deep tissues, so that the skin has a certain degree of mobility.

The water loss of our skin is mainly in the epidermis , which is related to the permeability of the stratum corneum. The stratum corneum provides us with barrier protection to prevent water loss. When the barrier is damaged, the skin is prone to lose moisture, leading to dry skin. However, if the skin's shielding effect is too strong, the nutrients supplemented to the skin will not be fully absorbed and the effect will not meet expectations. Therefore, it is best to have a moderate thickness and permeability of the stratum corneum.

Source丨Zhihu/see watermark

The dermis is of great significance to the human body . Generally, if the damage does not reach the dermis, the skin will not leave scars. The dermis is like a reservoir of the skin, and its water content can generally reach 70%~80%. It also acts as a water transporter. The hydration and moisturizing work we usually do is to replenish water to the dermis to maintain the health of the skin and prevent and reduce dryness and wrinkles. If the hydration work only stays on the surface and does not reach the dermis, then the beauty work will not play the role we want.

You should know that there are many ways for the human body to lose water, such as our body's respiration . Every cell has to breathe every second since it divides. One of the necessary substances for respiration is water. It can be said that water is the key to ensure the normal functioning of the human body. In addition, the human body is evaporating water all the time. In cold places, water evaporation is relatively small, but in hot places, even if a person does little exercise, he can feel the rapid loss of water from the human skin.

In addition, the transepidermal water loss (TEWL) of the human epidermis is also ongoing. When the TEWL value is higher, it means that the skin loses more water and the barrier function of the stratum corneum becomes worse. On the contrary, a decrease in the TEWL value indicates that the barrier is repaired.

Hydration ≠ Moisturizing

It is actually very difficult to replenish the dermis through daily skin care products such as facial masks and moisturizing sprays. If you want to really replenish the skin, it is very important to drink more water. Of course, if you want to use skin care products to prevent your skin from being dry, you must learn how to moisturize ! Usually, hydration means adding water to the skin to prevent it from being dry; while moisturizing means "locking" the moisture in the skin so that the moisture in the skin does not lose or slows down the loss rate.

Therefore, simply replenishing water cannot ensure that the skin is not dehydrated . It is like filling a swimming pool with water. If the swimming pool itself is leaking, we cannot fill it up.

Therefore, we need to hydrate the skin while preventing the moisture in the skin from escaping. Moisturizing cosmetics are actually a simulation of the human skin's moisturizing system. Moisturizing cosmetics also contain water, oils, natural moisturizing factors and other substances to lock in skin moisture and make the skin vibrant.

Common moisturizing ingredients include: glycerin, hyaluronic acid, collagen, etc. Therefore, the effective moisturizing factors added to cosmetics are generally composed of water absorbents (glycerin, propylene glycol and other alcohols), oils (commonly used are silicone oil, petrolatum and other mineral oils, lecithin, squalene and other intercellular lipids), and other types of moisturizing factors such as vitamins A, C, E, tea polyphenols, etc., as well as various antioxidants such as minerals and trace elements such as selenium and zinc.

Source: pixabay

We need to correctly judge our skin condition and choose the right products for ourselves. People usually like to use facial masks to hydrate the skin, but is it really the right way to hydrate the skin? Blindly over-hydrating the skin will not only fail to improve our skin, but will lead to the problem of "over-hydration", causing the water ducts of the hair follicles and sebaceous glands to absorb water excessively and expand.

Correct hydration requires both hydration and moisturizing. Do not over-care for your skin and choose skin care products that suit you, whether it is toner, lotion, essence or cream. Only by using it in moderation and using scientific methods to care for your skin can you achieve the best results.