Should you track your hydration?

It may be the next frontier in data-tracking; our experts weigh in on its necessity.

Wearables of the future could relay far more detailed data than a simple step count: LVL—a device that just raised over $640,941 on KickStarter—promises to track just how hydrated you are.

The connection makes sense. Research suggests dehydration negatively impacts sleep; fuels bad moods and cognitive decline; and leaves us confusing hunger with thirst. “When our body is missing the most key element that makes up who we are, we can’t focus—we’re focusing on survival instincts,” says Dustin Freckleton, M.D., LVL’s founder and CEO.

Identifying the best way to measure hydration is a bit of a holy grail in the medical community, says sports physiologist Allen Lim, Ph.D. If you’re clinically dehydrated—if you’ve lost about 2 or 3 percent of your body weight—your performance suffers, notes Lim. Any more than that, you risk heat illness and thermal injury.

But actually tracking this balance is a whole new beast. LVL measures hydration through infrared light technology, explains Freckleton. This kind of light can measure deeper into the body (and thus more accurately) than other trackers that use green light, the company says. It gathers data, they say, from plasma osmolality—or concentration levels in the blood.

Of course, there’s some skepticism. “These devices are likely very good at assessing relative changes from a baseline,” notes Lim. But while it sounds simple, measuring hydration isn’t simple. “No one’s quite nailed it yet,” he says. In part that’s because body composition, cardiovascular optimums, sweat rates, activity, age, altitude and diet all play a role. As do sodium levels. “Dehydration is not just about water loss, especially in an active person who is sweating,” notes Lim. Thus, the solution isn’t always more water. “What you really want is the right ratio of water to electrolytes.”

Doctors measure this through blood tests, fluctuations in blood pressure, kidney health, and body temperature, Lim says.

That said, thereis a case for tracking your water intake. And if LVL proves successful, it opens a new door for what we can track (and how we do it). Says Lim: “Any time we can learn more about our body and match that against our own perceptions, the better we get at basic care and nurturing of our bodies, our temples.”

LVL is slated to be on the market in summer of 2017. Until then, the human body is good at self-regulating, says Lim. Measure your own balance by paying attention to these three factors:

YOUR WEIGHT PRE- AND POST-WORKOUT:Weigh yourself before and after exercise. "The weight difference is equivalent to your water loss," Lim explains, "whereas the weight difference plus how much you drank is equal to your total sweat loss." If you lose more than 3% of your body weight during a workout, you need to drink more, especially if you feel signs of heat illness or big drops in performance. (Provided you hydrate post-exercise, Lim says a 100-pound person can lose 2 to 3 pounds safely, a 150-pound person can lose 3 to 4.5 pounds, and a 200-pound person can lose 4 to 6 pounds.)

YOUR THIRST LEVELS:Feel thirsty or crave salt? It’s time to drink and satiate that want for sodium. “Thirst responds to blood sodium concentration,” says Lim. “So when we get thirsty, we’re actually trying to regulate the sodium concentration of our blood. Relative to blood, we're losing a lot more water than salt." What this means: All things being equal, this causes blood sodium concentration to rise over time, which can make us thirsty. "In addition, a good goal is to take in anywhere from 300 to 500 milligrams of sodium per 16 ounces of fluid."

WHAT’S GOING OUT: If you’re going more than six times a day, you’re probably drinkingtoo much water, says Lim. “People always think about what goes in—how about tracking what comes out?” Most people make it to the bathroom every two hours; use this as a gauge, he suggests.