Do Energy Drinks Cause Dehydration During Exercise Evidence

You’re mid-workout, sweating buckets, and you grab a neon-colored energy drink. It promises wings, focus, and unstoppable power. But wait—does that can of liquid lightning actually dry you out?

Let’s bust the myth wide open. For years, people swore energy drinks cause dehydration during exercise. The culprit? Caffeine, the sneaky diuretic that makes you pee more. But here’s the twist: your body is smarter than a conspiracy theory.

Science says caffeine’s diuretic effect is mild—like, barely a whisper. Studies show that moderate caffeine (under 300 mg, about two energy drinks) doesn’t dehydrate you during exercise. In fact, it might help you perform better. Wild, right?

The Peep Show: Caffeine vs. Water

Imagine caffeine as that overly enthusiastic friend who yells, “Let’s go!” to your kidneys. But your kidneys have a boss: your brain. During exercise, your body prioritizes water retention for cooling and muscle function. So caffeine’s plea to pee gets ignored.

A 2010 study in the Journal of the International Society of Sports Nutrition had people chug coffee and then run on treadmills. Result? No difference in hydration levels compared to plain water. Zero. The diuretic effect only kicks in if you’re sedentary and chugging caffeine like a fish. But when you’re moving? Your body says, “Nope, we need that H₂O!”

Fun fact: A 2019 review of 18 studies concluded that caffeine’s diuretic effect is “negligible” during exercise. So unless you’re drinking six Red Bulls while sitting on a couch, you’re fine. Your workout is the real hydration boss.

The Sugar Trap—A Different Kind of Dehydrator

Here’s where it gets juicy. Energy drinks aren’t just caffeine; they’re sugar bombs. A single 16-ounce can packs 50 grams of sugar. That’s like eating 12 gummy bears in one gulp. Sugar pulls water into your intestines to digest it—that can mess with hydration.

Think of sugar as a thirsty sponge in your gut. It sucks water from your bloodstream into your stomach. If you’re already sweating, that could tip the scales. But here’s the kicker: most energy drinks now have sugar-free versions. Problem solved? Mostly.

But wait—there’s more! Artificial sweeteners in sugar-free drinks can cause bloating. Not dehydration, but your belly might puff up like a helium balloon. Not ideal for a Deadlift PR, but you won’t dry out.

What About Electrolytes?

Energy drinks often contain taurine, B vitamins, and guarana. But electrolytes? Almost none. Sodium, potassium, magnesium—that’s what you lose when you sweat. Most energy drinks are thirsty for these, not full of them. So if you’re doing a marathon or a hot yoga class, plain water or a sports drink might be better.

Children under 16 could be BANNED from buying energy drinks under

Here’s a quirky comparison: Energy drinks are like a sports car with no tires. They give you speed (energy) but no grip (electrolytes). Sports drinks are the sensible SUV—boring but reliable. Pick your ride wisely.

One study even found that drinking a sugar-free energy drink before exercise increased urine output by 12%. But that’s from the volume of liquid, not the caffeine. You’d get the same effect from drinking 12 ounces of tea. So blame the water, not the ginseng.

The Real-World Test: You vs. Your Can

Try this: Down an energy drink, then hit the gym. Notice anything? You’ll probably feel more alert, maybe a bit jittery. But you won’t suddenly turn into a desert. Unless you chug it on an empty stomach—then you might get the poo-zles (digestive chaos). But dehydration? Unlikely.

Research from the University of Birmingham had athletes drink a caffeinated energy drink before a 45-minute run. Their urine color (yes, scientists measure that) showed no dehydration. The only thing “dried out” was their opponents’ egos.

So why does the myth persist? Because your grandpa once drank coffee, ran a mile, and peed his pants. He blamed the coffee, but it was probably just old age. Myths stick when they sound plausible, even if science says “meh.”

The Bottom Line—But With Sass

Energy drinks do not cause dehydration during exercise—unless you guzzle them like a fish and sweat like a pig. The real dehydrators are alcohol, extreme heat, and ignoring thirst. Caffeine is a scapegoat.

If you’re worried, pair your energy drink with a big glass of water. Or choose a sugar-free version to dodge the gut sponge. And if you’re doing a 10-hour hike? Stick with electrolyte tabs. But for a regular workout? Go ahead and sip your liquid lightning—it won’t shrivel you up.

Here’s your takeaway: Stay curious, don’t believe every health “tip” you hear, and remember that your body is a brilliant machine. It handles caffeine like a champ. Now go crush your workout—and maybe pee afterward, just in case.