If you’re hell-bent on staying hydrated in the name of a glowing complexion, the following may come as a shock: Drinking water doesn’t replenish dry skin—at least not in the way you may have been led to believe, according to esthetician Renée Rouleau.

Rouleau, who counts Demi Lovato and Lili Reinhart as clients, took to Instagram to dispel what she calls the number one skin hydration myth: that drinking water elicits hydrated, bouncy-looking skin. Au contraire, Rouleau says consuming water is actually “the least efficient way to hydrate the skin.”

It’s enough to make one’s head swim—but the biology checks out.

Simply put, water we ingest travels a long and winding biological road—and, unfortunately, there’s no shortcut to the skin cells. “Water will run through the intestines, get absorbed into your bloodstream, and then get filtered out by the kidneys,” Rouleau explains. “At this point, it will hydrate the cells inside the body,” she continues, “but to expect it to reach the outside layers of the skin, known as the epidermis, is just not possible.” Instead, skin hydration is more of a sebaceous gland and skin-barrier issue, Dendy Engelman, MD, a dermatologist based in New York City, previously told Well+Good.

It’s a lot to gulp—but don’t ditch the water bottle just yet. While H2O may be a wash from a skin hydration standpoint, it’s nevertheless crucial for optimal organ, tissue, and lymph functioning. Moreover, since all of your systems work together, keeping ‘em hydrated has a trickle down effect on your appearance. For example, a well-oiled—er, watered—lymph system keeps puffiness at bay. Another aesthetic bonus, according to Dr. Engleman: “Adequate hydration helps the skin to optimize circulation.” (Blood flow equals glow!).

As for achieving moist, bouncy, watery skin? “Applying topical hydration with skincare products will always be the most effective way to plump up thirsty skin cells,” says Rouleau.

To heed this advice, look for products containing hyaluronic acid (HA), a moisture-loving molecule that holds up to 1,000 times its weight in water. Many essences, like H2O+ Priming Water Essence ($40), deliver ample HA without adding heaviness to your skin-care routine. You can also sneak HA into your sunscreen; try Peter Thomas Roth Water Drench Hyaluronic Hydrating Moisturizer SPF 45 ($52), or Neutrogena Hydro Boost Water Gel Sunscreen SPF 50 ($10).

Glycerin is another hydrating hero ingredient to look for. In fact, you’ll often find it paired with hyaluronic acid. An excellent humectant, glycerin is the (not-so) secret sauce in many water creams, including the Belif The True Cream Aqua Bomb ($52) and Simple Water Boost Hydrating Gel Cream Face Moisturizer ($4).

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