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Figure Out Whether You’re Dehydrated in Seconds by Stepping on a Super-Smart Scale

Kells McPhillips

September 25, 2018

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Photo: Getty Images/Hoxton Chris Ryan

Now that experts have debunked the long-held idea that the color of your pee can be used as a litmus test for your hydration levels (really, naysayers), you'll need to keep tabs on your H2O stores some other way. You could try the "pinch test"—which sounds way more violent than it actually is, promise—or you could take a more hands-off approach and simply step on the scale.

But not just any scale. New fancypants smart scales can measure your body water percentage (BWP) by sending a harmless electric current through the body (a process called bioelectric impedance analysis). Because electricity travels faster through water than solid mass (AKA your organs, bones, muscles, all that fun stuff), the scale can use the amount of resistance encountered by the electric current to calculate your BWP.

Once your BWP pops up on the screen, how will you know whether that means you need to reach for your S'well, stat? According to Albert Ahn, MD, an internal medicine doctor at NYU Langone, your particular BWP needs will vary depending on your age, gender, and body composition (you can use a handy online calculator to help you determine yours). Generally though, a woman's percentage should fall between 45-50 percent, while a man's should be between 50-65 percent. "Those who are very athletic and active should have an additional 5 percent of body water percentage," adds Dr. Ahn.

If weighing yourself on the reg might doesn't sound like a healthy lifestyle decision for you, Dr. Ahn says, "In general, the most common way that we are able to regulate our body water percentage is through our thirst reflex," he says. The body is pretty good at letting you know what it needs—you just need to pay attention.