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Published on November 23, 2021

closeup of sweat on skin

What We Lose in Sweat

It makes us moist, but it also keeps us cool, no matter how hard we run, how nervous we get or how high the humidity. Sweat might seem like a gross byproduct of biology, but it’s vital – and often misunderstood.

We lose important chemicals when we sweat – but we can replace them to be at our healthiest.

“Workouts that last an hour or more can drain our electrolytes,” said Anna Heronimus, RD, LN, a registered dietitian with Avera Human Performance Center. “We can replace almost all we need with a balanced diet.”

While 99% of it is simply water, that other 1% of sweat is electrolytes, which are important nutrients our cells need. Minerals such as potassium, magnesium, calcium and sodium work together to produce electrolytes, which help move water around in our cells, as well as hold water where it’s needed.

“There’s no ‘best fit’ for everybody – some people might need sports drinks after a workout. Others might be better off with a good meal and water,” Heronimus said.

Sweat Analysis Helps Athletes

One way to evaluate what we’re losing in a workout or competition is through a process called sweat analysis. Using a complex formula, as well as pre- and post-workout weigh-ins, sports science professionals can figure out your “sweat rate.”

“Baseline fitness, stress, weather – there are many factors that go into this measurement,” Heronimus said. “We do these regularly on football players, runners – many different levels of athletes.”

In some cases, especially when it’s hot out, an individual can lose as much as 3 ounces of electrolytes in a long workout or game. In terms of weight, in an intense setting, some people can lose 2 pounds of weight. That figure goes into the analysis and helps an athlete realize the best way to recover and replace what they lose.

Any athlete or individual who loses 2 pounds of weight during a workout needs 32 to 48 ounces of fluid to rehydrate – in addition to the electrolytes they lose.

How to Replace What We Lose

When it comes to putting those vital nutrients back into our bodies, food is the best place to begin.

To get refilled on electrolytes, these foods can help:

  • Crackers, beef jerky and sports drinks can help replace sodium
  • Leafy veggies, especially spinach, and bananas help restore potassium
  • Dairy products and broccoli are great for getting back calcium
  • Peanut butter and other nuts provide our bodies with magnesium

Sports drinks are another option for replacing electrolytes. “However just because it’s a sports drink doesn’t mean it’s going to meet your electrolyte needs,” Heronimus said. “Each one has a different make up of electrolytes.”

Some may have large amounts of sodium, while they offer no potassium or magnesium. If you’re a heavy sweater, drinking certain sports drinks might not cover your needs. You might not want the sugar content of some sports drinks. And people with chronic conditions, such as high blood pressure, should be careful, for example, by not getting too much sodium.

Talking to your primary care provider is the best way to head off possible issues or get fact-based answers on your individual health, workouts and exercise.

You can also work with an expert like Heronimus to get your sweat rate analyzed.

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