Drink the Water — Week 29: The surprisingly complicated science of staying hydrated

Hey {{first name | reader}},

It’s Tuesday, which means your weekly fitness check-in. Welcome to Week #29.

The World Cup is over, and we can only hope that the hydration breaks that interrupted every single match—even the ones played indoors under climate-controlled conditions—will not return in 2030.¹

Back when I ran marathons, I never carried water on training runs. I would plot a route past a few drinking fountains, attempt to “hydrate beforehand,” and then drink a great deal afterward. The reward for this system was terrible cramps in my side and, occasionally, my legs.

Despite detesting the World Cup hydration breaks so much that I have moved my rant out of the footnotes and into the lead, I recognize that hydration is important—particularly when you’re training. I have learned. I now carry the water.

Humans are roughly 60% water, and nearly everything our bodies do depends on it. Water helps move nutrients around, regulate temperature, lubricate joints, and keep our cells functioning. We lose it through urine, breathing, and sweat. The hotter the weather and the harder the exertion, the more we generally need to replace.

How much? Annoyingly, it depends.

Body size, climate, activity, health, diet, and even altitude all affect water needs. We get water from plain water, certainly, but also from coffee, tea, other beverages, and food. There is no single number that works perfectly for everyone.

Here is my current system:

Before the gym, I drink a 20-ounce Yeti tumbler of coffee, with caffeine and a dash of unsweetened almond or coconut milk. I take a 20-ounce bottle of ice-cold water to the gym and almost always finish it. Over the rest of the day, I try to drink two 40-ounce tumblers of water.

On my long Saturday hikes, I carry a backpack with a two-liter water bladder and typically drink at least half of it. When I travel, I take an empty 30-ounce bottle through airport security, fill it before boarding, and top it up whenever water appears.

I have learned my lesson. I no longer wait until I'm home and attempt to correct the situation in one dramatic gulp.

I don’t usually add electrolytes to my water. Perhaps I should more often: I have low blood pressure, I’m prone to fainting, and I have been specifically advised to make sure I get enough salt. But most people eating a reasonably balanced diet will get the sodium, potassium, and chloride they need without buying expensive tropical-flavored powder.

Electrolytes become more useful during long or intense workouts, in hot weather, or if you sweat heavily. We have all seen that guy—it is always a guy—who leaves a small pond under the spin bike or pours torrents onto the elliptical. If you are that guy, a sports drink may actually be for you.

I also heard a great deal of mumbo jumbo about coffee while growing up. Coffee stunts your growth. Coffee doesn’t count as hydration. You must drink an extra glass of water for every cup of coffee.

No. Caffeine can have a mild diuretic effect, but the liquid in coffee still counts toward hydration—and regular coffee drinkers develop some tolerance to that effect. Caffeine can also improve some forms of athletic performance.

At last, science produces the result I wanted.

Question: How do I know if I’m getting enough water?

Answer: Start with the simplest available evidence: look at your pee.

Pale yellow generally means you’re doing fine. Consistently dark yellow urine, infrequent trips to the bathroom, dry mouth, headache, dizziness, or unusual fatigue may mean you need more fluid. Urine color isn’t a perfect test—medications, supplements, and food can change it—but it is a useful everyday signal.

Thirst is also a signal. For most healthy adults going about an ordinary day, drinking when thirsty works reasonably well. During long workouts, very hot weather, illness, or travel, however, it is smarter to drink regularly instead of waiting until you feel parched.

Myth: Everyone needs eight glasses of water a day.

Reality: The popular eight-glasses rule gives us the illusion of precision without delivering much precision.

The National Academies’ general benchmarks are about 2.7 liters—or 91 ounces—of total water per day for women and 3.7 liters—or 125 ounces—for men. But “total water” includes coffee, tea, other beverages, and the water in food. Roughly 20% of the average person’s water comes from food.

Your actual needs may be higher if you exercise heavily, sweat a lot, live somewhere hot, or spend the day hiking. They may also be lower than the amounts promoted by the internet’s most aggressive water-bottle enthusiasts.

And if you are a fruit eater—which we know I am not—you may be getting a substantial amount of water from foods that can be up to 90% water.

There is no one-size-actually-fits-everyone number. There rarely is.

At some point in childhood, I realized that I strongly preferred eating my calories to drinking them. I stopped drinking juice, soda, sweetened tea, and nearly every other sugary beverage.² As a result, I became something of a plain-water enthusiast.

Fortunately, San Francisco has excellent-tasting tap water. I recognize, however, that many people simply do not enjoy plain, unadulterated water—even when it comes from Hetch Hetchy or a bottle featuring a mountain no one has ever visited.

That is where infused water comes in.

The method is almost insultingly simple: fill a pitcher with water, add flavorful things, and let it sit in the refrigerator for a few hours. Citrus, cucumber, herbs, ginger, berries—possibly olives, although that may just be a very weak martini.

A few combinations:

Cucumber, lime, and mint: ½ sliced cucumber, 1 sliced lime, and 8–10 torn mint leaves.

Lemon, ginger, and cayenne: 1 sliced lemon, 2 inches of peeled and sliced ginger, and a tiny pinch of cayenne.

Black tea and orange peel: Steep 2 black-tea bags briefly in 4 cups of water, remove the bags, and add several strips of orange peel. Chill before drinking.

And two for people who, unlike me, believe fruit is delicious:

Strawberry and basil: ½ cup sliced strawberries and 6 torn basil leaves.

Grapefruit and rosemary: ½ sliced ruby-red grapefruit and 2 sprigs of rosemary. The woodsy herb balances the sharp citrus.³

If you would like to dive very deeply into water—and I do mean deeply—listen to Episode 114 of the Huberman Lab podcast: “How to Optimize Your Water Quality & Intake for Health.”

Huberman covers hydration timing, exercise, caffeine, minerals, water filtration, and why general intake recommendations may or may not apply to you. The episode is more than two hours long, because it is Huberman Lab, but the first 30 minutes contain most of the practical hydration advice.

Track your hydration for three days.

Write down:

Don’t chase an arbitrary gallon or force yourself to meet a formula pulled from social media. Look for patterns. Are you drinking almost nothing until dinner? Finishing workouts with a headache? Carrying a 40-ounce tumbler everywhere but never actually drinking from it?

The goal is not to win hydration. The goal is to notice whether your current system is working—and adjust if it isn’t.⁴

Stay strong,
{{first name | reader}}

P.S. The hydration breaks were excessive. The hydration was not. There’s a difference.