How to stay hydrated

What Does It Mean To Be Hydrated?

We throw around the word “hydration” a lot, so let’s define it to get on the same page. Hydration means maintaining fluid balance in the body. To get a picture of how this works, think of your body as a vehicle for water molecules. Water enters the body when you drink it or eat food containing water (like cucumbers and watermelon). Water exits the body through urine, sweat, breathing, and feces. A wise approach to healthy hydration is to keep the gains and losses roughly equivalent, avoiding too little or too much water in the body.

Much of this fluid balancing systemOpens in a new tab is automatic. Thirst regulates water inputs, while the brain, kidneys, and hormones (like vasopressin) regulate water outputs. The body constantly strives to balance the two sides of the water ledger. An optimal balance helps keep your blood flowing, brain floating, sweat glands sweating, and more.

Electrolytes such as sodium, potassium, and magnesium also support fluid balance, and the body seeks to balance their inputs and outputs, too. For example, not consuming enough sodium can cause the body to release sodium retention hormones like aldosterone and norepinephrine (these hormones may explain why salt restriction is linked to side effects like elevated baseline heart rateOpens in a new tab). As with fluids, the body is trying to balance the electrolyte ledger.  

To summarize, staying hydrated is a matter of getting enough fluids and electrolytes so the inputs and outputs stay roughly balanced. Let's talk about how to calibrate fluid inputs.

How Much Water Should You Drink?

For the water part of the hydration equation, you’ll want to consume enough liquid to replace the water exiting your body — this helps maintain fluid balance. For most folks, drinking to thirst is the most efficient way to do this. Let’s take a deeper look at why this is.

Thirst is a well-calibrated mechanism. Receptors in your brain continuously monitorOpens in a new tab your blood's volume and sodium concentration. Low blood volume and high blood sodium are signs of insufficient water in the body — both alert the receptors to trigger thirst. Then you drink, fluid balance is restored, and thirst fades.

When you don’t drink to thirst, a couple things can go wrong:

1. If you don’t drink enough, you may not be replacing the fluids you’re losing (dehydration).
2. If you drink too much, you can overwhelm the body with too much fluid (overhydration).

Let's review each of these hydration problems.  

#1: Losing too much fluid (dehydration)

Dehydration means net water loss from the body. You become dehydrated if you lose more water than you consume — from, say, sweating without adequately rehydrating. 

The most common dehydration symptomsOpens in a new tab include headaches, fatigue, muscle cramps, weakness, dry mouth, dark urine, and decreased urinary volume. Being dehydrated also makes the heart work harder during activity, impairingOpens in a new tab exercise performance. Read our performance hydration articleOpens in a new tab to explore this topic. 

Drinking to thirst can help folks avoid dehydration. Athletes may become temporarily dehydrated during and after training, but drinking to thirst eventually restores the balance. One exception is older adults. These folks can have impaired thirst mechanismsOpens in a new tab and more difficulty accessing fluids, so they may want to sip electrolyte water throughout the day. Learn more hereOpens in a new tab. 

#2: Gaining too much fluid (overhydration)

Drinking to thirst isn’t just helpful for preventing dehydration. It also can help people avoid overhydration, or consuming too much water. Overhydration dilutes blood sodium levels, making it harder for sodium to support important functions (like cellular communication). 

Many overhydration symptomsOpens in a new tab — headache, fatigue, muscle cramps, weakness — overlap with dehydration symptoms, so figuring out which is which can be tricky. Elite endurance athletes often hydrate to prevent dehydration while ignoringOpens in a new tab the perils of overhydration. The mix-up can be dangerous and, in rare but extreme cases, fatal.

But most cases aren't extreme. Most folks who drink plain water to replace sweat loss feel "off" or "low energy" throughout the day. I've been there! Drinking to thirst is part of solving this overhydration problem, but we need to talk about electrolytes too. 

How Electrolytes Support Hydration (Especially Sodium)

Electrolytes are another key componentOpens in a new tab of healthy hydration, playing an important role in helping balance fluid gains and losses.

Sodium is an essential mineral for regulating fluid balance outside cells. Sodium lends volume to blood plasma, which helps maintain the blood pressure that allows blood to circulate and nourish tissues. 

Sodium also primes the sodium-potassium pump, a protein in every animal cell that helps nerve impulses fire and allows cells to communicate with each other (this communication allows us to think, move, and breathe). Learn more about the pump hereOpens in a new tab. 

Potassium complements sodium’s role, supporting the sodium-potassium pump, and also regulating fluids inside cells, which helps cells maintain their volume and function properly. Learn more about potassium hereOpens in a new tab. 

Magnesium indirectly affects fluid balance by helping regulate heart contraction, which moves blood throughout the body. It also supportsOpens in a new tab over 300 enzymatic reactions. Learn more about magnesium hereOpens in a new tab.

While all three of these electrolytes play important roles in hydration, sodium is an especially important one to pay attention to. Many folks don’t consume enough, whether that’s because they believe they should avoid it, don’t consume enough through their diets, or are active and lose large amounts of sodium through their sweat. Read our guides on sweat rateOpens in a new tab and sweat sodium concentrationOpens in a new tab to learn more about replacing sweat losses from exercise, or check out our Sodium Intake CalculatorOpens in a new tab for some quick math. A simple guideline, though, is to drink salty fluids to thirst. 

Tips for Staying Hydrated

Now that we've covered the two halves of our simplified hydration equation (water plus electrolytes), let's review practical tips to keep your hydration system running smoothly. 

#1: Drink to thirst

I know you get it by now: Drinking to thirst (and not beyond) helps keep your fluids balanced so you can avoid dehydration and overhydration. 

#2: Get enough electrolytes through diet

A whole foods diet full of electrolyte-rich foodsOpens in a new tab and salted to taste are the first place to start when dialing in your electrolyte intake. Science-backed ranges you can aim for are  4–6 grams of sodiumOpens in a new tab, 3.5–5 grams of potassiumOpens in a new tab, and 400–600 mg of magnesiumOpens in a new tab, but every body is unique. It can be worth testing out different intakes and listening to your body.

#3: Enjoy electrolyte drinks

While diet is the first place to start for electrolyte needs, it can be difficult to consume enough sodium, potassium, and magnesium solely through food and the salt shaker. That’s where electrolyte drinks can help fill in the gaps. 

Of the electrolytes, sodium may be most lacking in a whole foods diet. Active, healthy folks also tend to lose lots of sodium through sweat. That’s why LMNT Drink MixOpens in a new tab and LMNT SparklingOpens in a new tab deliver 1 gram of sodium in each stick pack and can, in addition to 200 mg of potassium and 60 mg of magnesium.

Before signing off, let's repeat the hydration rule of thumb: Drink electrolyte water to thirst. You'll feel the difference when you get your fluid balance right. Stay Salty and hydrated, everyone.