New Study: This Is the Precise Amount of Water To Drink for Juicy-Looking Skin

Updated: Jun. 07, 2024

You've heard you need to hydrate for supple skin—now researchers in Korea surface refreshing new insights, including about the skin's most essential function.

Drinking water helps your skin look young. We’ve all heard this colloquial wisdom—but for many, the very phase of life when you’re most invested in rejuvenating your glow happens to be the era when certain body parts (like the bladder) get more sensitive to beverage intake, and when the day often feels too fast-paced to keep running to fill that glass.

Now, dermatology and metabolism researchers in Busan, Korea have pinpointed the amount of water that makes a scientific difference in keeping the skin moisturized from within.

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A June 2024 study published in the Annals of Dermatology aimed to analyze the benefits of moisturizer application and hydration on the human skin barrier, which is the outermost layer of our skin that protects the body from environmental threats and maintains its water balance.

The study involved 43 Korean women ranging between their twenties and forties, average age 28 years. Twenty-two participants were considered part of the “high daily water intake group” (more than one liter), and 21 participants were considered part of the “low daily water intake group” (less than one liter). Each group was then subcategorized into one of four more categories:

  • Group 1: Additional water intake of two liters each day.
  • Group 2: Additional moisturizer application three times a day.
  • Group 3: Both additional two-liter water intake each day and additional moisturizer application three times a day.
  • Group 4: A control group that maintained their typical water intake and moisturizer application.

The researchers followed participants over four weeks, evaluating the skin surface hydration of each participants’ forehead, left cheek, left forearm, left shin and left hand dorsum, which is the back of the hand.

Using a specialized probe that measured the density gradient of the water evaporation from the skin, the researchers measured skin moisture at the beginning of the study, then after two weeks, and finally after four weeks.

After the fourth week, the researchers noted a few “significant differences” for certain groups. Group 1’s stratum corneum, the superficial layer of the epidermis, showed an increase in hydration in the left shin.

Groups 2 and 3 also both saw an increase in stratum corneum hydration on their left forearm, left hand dorsum and left shin.

Perhaps most notably, the research team reports that skin moisture “showed a tendency to be higher on the forehead, left cheek, and left forearm of the [high daily intake water group], which is thought to be contributed by one liter of daily water intake to a certain extent.”

That being said, simply increasing water intake did not cause major changes in skin health and appearance for participants—that needed to be supplemented with a moisturizer regimen.

Also worth noting is that the study was conducted on a limited sample of participants hailing from one region of the world, while the research team also noted that relative humidity in the location where the measurements were taken stayed steady between 50% to 52%.

All factors considered, the results of this study may offer a solid target for daily water intake: If you’re getting a liter a day, you’re probably doing your body good.