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2% Hydration Guide: Part II

2% Hydration Guide: Part II
Re-hydrating with Jason McCarthy after he ran me through the 100-Pound One-Mile Challenge at Goruck HQ.

Everything you need to know about hydration supplements.

You’ll learn: When to use electrolyte supplements, their potential downsides, the truth about salt and hydration, when sugar is good and bad in hydration supplements, and more.


  • Happy birthday to my wife, Leah, the ultimate human.
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Welcome to Part II of our two-part series on hydration and hydration supplements. In Part I, we looked at:

  • A brief history of hydration and hydration supplements.
  • What dehydration is and how it impacts us.
  • Whether dehydration impacts athletic performance.
  • Three smart guidelines for hydrating for exercise.

Today we’re covering hydration supplements.

  • Who may want to use them and why.
  • Their potential downsides (necessary reading).
  • The truth about salt and hydration (there are some wacky claims out there).
  • Whether sugar is good or bad in hydration supplements.
  • What to look for in a hydration supplement.
  • A quick rapid fire of hydration questions.

As a reminder, I got down this hydration rabbit hole after a visit to the community gym. A guy in his 50s, who didn’t look entirely healthy, used a hydration packet—a popular brand you see all over Instagram and hear advertised on podcasts. He exercised for 10 minutes and left.

The exercise is good. But I wondered about the hydration packet. It contained a significant amount of salt—and the guy had only exercised for 10 minutes in an air-conditioned gym.

I wanted to understand hydration better and the upsides and downsides of hydration supplements.

I read studies and called two great experts in this domain, Mike Roussell and Trevor Kashey. Both are PhDs who have conducted research and worked with elite athletes (you can work with them both. Mike is here, Trevor is here. Or follow them on Instagram for their free wisdom. Mike is here. Trevor is here.)

Let’s roll …

Who may want to use hydration supplements

In short

Athletes doing long and sweaty workouts and people with clinical conditions that require high intakes of salt and other electrolytes.

The details

Roussell explained where to start well: “Step one is being honest about your activity level and your level of exertion.”

Most active people get plenty of sodium and electrolytes through their regular diet.

Even if you’re eating a primarily whole-food diet, you’re still likely taking in around 3,000 milligrams of sodium a day (sodium gets added to all sorts of healthy foods). To live, you only need 180 milligrams a day. The American Heart Association suggests we aim for between 1,500 and 2,400 milligrams a day.

If you’re taking salty hydration supplements for workouts that aren’t long and sweaty or using them as a flavor enhancer in your water in daily living, you’re likely adding more salt on top of a diet that already has enough salt. And that can come with downsides (more on that below).

Roussell’s take was this:

Let’s say you have a really sweaty workout for one hour. You might become sodium depleted in that hour. But you’re going to replace the sodium you lost when you eat a post-workout meal, even if that’s a couple of hours later.

Electrolyte supplements help when you’re training intensely for two or three hours. During hour one, you’re probably becoming depleted (in electrolytes). In hour two, you’re training while depleted. So your performance drops. Once you move into hour three, you're screwed.

So electrolyte drinks and replacing sodium during a workout is more about supporting the second hour and beyond. And I think that's where people go wrong. If you train for an hour or 90 minutes, depending on how hard you train, you likely don't need to supplement during your workout, because you're not training long enough to experience problems. You’ll drink water and eat food when you're done. So everything equals out.

He gave me an example. His son plays lacrosse and had a recent tournament in 85-degree weather. He was playing multiple hour-long games in one day. “So we gave him a 12-ounce gatorade, electrolyte pack, and 21 ounces of water—or about a liter of fluid—during games and between games so he didn’t get behind the eight ball. But most people aren’t getting behind the eight ball. They’re not even getting close to the eight ball.”

Other clinical conditions can lead someone to require more salt. For example, brain injuries can impair your ability to regulate sodium and water. Or diarrheal diseases can lead to low levels of electrolytes (more on that below).

Potential downsides of electrolyte supplements