“I don’t like pickles. I don’t like the taste of pickle juice, but for some reason it was the only thing that was working.”

An athlete told me this about a long race where nothing else would stay down. Hating pickles and still reaching for pickle juice isn’t random. More often than not, that’s your body asking for the sodium your bottles weren’t giving it.

Another athlete mentioned the white marks drying on their hydration vest after long runs. Same story. That white crust is salt you lost in your sweat.

So how much sodium do you actually need? The answer starts with a question I ask almost every athlete I work with: do you think you’re a salty sweater or a heavy sweater?

Two different things

Those sound like the same thing, but they aren’t.

• A heavy sweater loses a lot of fluid. You’re drenched, dripping, and going through bottles fast.
• A salty sweater loses a lot of sodium in every liter of sweat. That’s the white marks, the stinging eyes, and the gritty feeling on your skin.

You can be a super salty sweater but not a heavy sweater, or the other way around. But if you’re a heavy sweater, you’re probably losing more sodium no matter what, just because there’s so much more sweat. How much sodium you lose comes down to both at once.

How salty is salty?

Sweat sodium varies a lot from person to person. The lowest I’ve seen is around 400 milligrams of sodium for every liter of sweat lost, and the highest is up to 2,000. That’s a five-fold difference between two athletes who might be riding side by side.

Most folks tend to sit around 800 milligrams per liter, and that’s a useful starting point if you’ve never been tested. Even so, I think it can be wildly underestimated just how much sodium that is over a long day.

Two riders, same sodium loss

Here’s an example that makes the salty vs. heavy difference click.

I once compared my numbers with an athlete I was working with, over the same kind of effort. Her sweat sodium concentration was about 600 milligrams per liter, and she lost about two liters of sweat. Mine is 1,200 milligrams per liter, and I lost about one liter.

• Her: 2 liters × 600 mg = 1,200 mg of sodium
• Me: 1 liter × 1,200 mg = 1,200 mg of sodium

We lose the same amount of sodium, for completely different reasons. She’s a heavy sweater and I’m a salty one. That’s why copying someone else’s bottle recipe doesn’t always work, even when you ride together.

What stays consistent and what changes

How salty your sweat is stays fairly consistent for you. It can shift a little, for example as your body adapts to training in the heat, but it isn’t swinging wildly from one ride to the next.

What changes day to day is how much you sweat. A cool, cloudy morning and a 95-degree afternoon can look completely different, even at the same effort. So a hot day doesn’t make your sweat saltier. It means more sweat, which means more total sodium lost.

Match your bottle to your sweat

The idea is to make the fluid you’re taking in roughly the same concentration as what you’re losing when you sweat. Sweat isn’t just water. It’s water and sodium, so replacing only the water leaves you short.

If you don’t know your number, start with the average of about 800 milligrams of sodium per liter. In practice:

• A 24 oz bottle (about 700 ml) should have at least 500 to 600 mg of sodium
• A 500 ml flask should have about 400 mg

Then drink to thirst. Because you’re matching concentration rather than chasing a set number of milligrams per hour, the sodium follows the fluid. On a hot day you’ll drink more and get more sodium automatically. On a cool day you’ll drink less, and that’s fine too.

Let thirst tell you something

Thirst is useful information. If you’re drinking a full-strength bottle and you’re still really, really thirsty, that can tell us you might need a little more sodium in it.

Some other signs you’re coming up short on sodium:

• Craving salty things mid-race, even things you normally don’t like (hello, pickle juice)
• White, crusty marks on your kit or vest
• Drinking plenty and still finishing noticeably lighter on the scale
• Feeling crummy on hot days even when your carbs are dialed

That last one is common. If it’s a hot day and your bottle has 80 grams of carbs but only a little sodium, you can drink through all your carbs and still feel pretty crappy.

When in doubt, err toward more

In my experience, it’s better to be slightly over-salted than under-salted. Your body has ways to get rid of excess sodium, but it doesn’t have ways to make more. The athletes who end up in the med tent needing an IV are often the under-salted ones, not the over-salted ones.

Very rarely do I see athletes dealing with the effects of too much sodium. What I see far more often is people unintentionally under-salting themselves. Even athletes who come in convinced they’re the saltiest sweater I’ve ever seen often aren’t hitting the average yet.

Ways to get more sodium in

If you’re a salty sweater, a heavy sweater, or both, there are a few easy ways to raise your intake without drinking something that tastes like the ocean:

• Make your bottle stronger. Add an extra half or full scoop of your electrolyte drink mix, or add a scoop of an unsweetened electrolyte mix, which brings the sodium up without piling on more sugar.
• Salt tabs. Most have around 200 milligrams of sodium each. Take them with water or your bottle, not on their own between aid stations. Sodium needs fluid to do its job.
• Salty real food. Jerky or meat sticks, pretzels, salted potatoes and crackers all add sodium and a nice break from sweet.

If you’re wondering why sodium matters this much for hydration in the first place, I get into how it helps your body hold on to fluid in How to Fuel the First Hour of a Gravel Race Without Falling Behind.

Whatever you add, test it in training first. Find an amount that sits well with your gut and makes you feel better on the bike. A number you can tolerate every single time beats a perfect number you can only hit on paper.

Want to know your actual number?

The 800 mg per liter average is a great starting point, but it’s still a guess. A sweat sodium test is the most accurate way to know how salty you actually are. It’s quick, you don’t need a bike or a treadmill, and it only takes a small patch of sweat on your forearm.

What I love about it is that athletes leave with an action step. They know how much sodium they’re losing, instead of guessing and adding random scoops.

The bottom line

So, salty sweater or heavy sweater? For a lot of people, the answer is that they don’t know yet. Start with about 800 mg of sodium per liter, drink to thirst, pay attention to the signs, and adjust from there. When in doubt, lean toward a little more.

Building a hydration and sodium plan around how you actually sweat is part of what we work on inside the Gravel Performance Nutrition Course and in 1:1 sessions. If you’re tired of guessing, either one is a great place to start.