The best (and worst) beverages to sip when you’re dehydrated

Summer’s right around the corner, but the heat is already on. From unrelenting sunshine to sizzling grills, feeling hot (and cooling down) are part of the daily grind now. PopSci is here to help you ease into the most scorching season with the latest science, gear, and smart DIY ideas. Welcome to Hot Month.

With summer right around the corner and the thermostat ticking up, it can be tempting to reach for the coldest looking thing in sight to quench your thirst. But when it comes to hydration, not all drinks are created equal. 

Usually, when we’re feeling thirsty, we’re trying to combat symptoms like dry mouth, tiredness, headaches, and dizziness. But dehydration is not solely due to the loss of water in our system. It also means we’re low on  electrolytes—minerals that carry an electrical charge. These electrolytes, like sodium and potassium, are agents of balance. They help with bodily functions like regulating the pH levels of your blood, balancing fluid levels, and helping blood clot. 

“The human body as a whole is roughly anywhere from 60 to 65% made up of water. In order to have all of your normal metabolic functions, you have to have adequate fluids,” says Bailey Jones, a registered dietician and assistant director of performance nutrition at Indiana University. “Fluids are going to play a role in thermoregulation and the transport of nutrients and waste products, and also act as a cushion for your joints. If the body is dehydrated, it just can’t do any of those functions very well.”

Hydration isn’t a zero-sum game. It’s not that liquids are either hydrating or dehydrating—some things are less hydrating than we might assume, or their hydration properties might come at the cost of other effects on our bodies. Here’s a look at the usual suspects of dehydration. 

Coffee

Coffee has long been shamed as dehydrating. That’s because caffeine has a diuretic effect—it makes you feel like you need to pee, which gives you an opportunity to expel fluid and electrolytes. This may technically be true, but those effects aren’t powerful enough to offset coffee’s hydrating properties. 

“It’s still a liquid,” says Jones. “Any small dehydrating effect is essentially negated by the fact that you’re still consuming fluid.” 

[Related: Does drinking hot liquids on a hot day actually cool you off?]

If you added more water to your coffee, or even a splash of milk, you could even further offset the balance between liquid intake and the effects of caffeine. 

But that doesn’t mean that espresso and ice should form the bulk of your fluid intake. Though you might feel refreshed and hydrated, excessive amounts of coffee will send your heart racing—so you don’t want to rely on it for all your fluid needs.

Juices, sodas, energy drinks, and sports drinks

If you’re looking to hydrate with a soft drink, your main concern should be balancing how well the fluid can hydrate you with how negatively its additional sugar content will affect you. Sodas and most fruit juices weigh in somewhere in the middle. They’re good for hydration in the sense that there is liquid flowing into the body, but the high sugar content could have downsides.  The higher the concentration of sugar in your blood, the more water your cells will lose through osmosis to maintain equilibrium.

If you can get your hands on 100 percent natural juice, that can be an excellent source of water since you’re staying away from useless added sugars. You could also go straight to the source and eat fruit. Some fruits are heavier lifters than others: watermelon, grapefruit, and cantaloupe have particularly high water content. Fruits also have the added bonus of replenishing electrolytes and vitamins. 

Energy drinks like Redbull have few redeeming qualities. While they might perk you up with caffeine, their high concentration of sugar means that your kidneys work overtime to produce more urine to flush the sugar from your system, which isn’t going to help you stay hydrated. 

But what about sports drinks like Gatorade?

“Water and sports drinks are usually the go-to recommendation, especially during training,” Jones says. “They’re losing fluids through sweat, but they’re also losing electrolytes, and that’s where adding a sports drink is going to provide some of the sodium, potassium, and chloride— basically the electrolytes that you won’t find in plain water.”

Even if you’re not a high-performance athlete, the low-sugar, low-calorie option of sports drinks tips the scale in favor of more hydration at a lower cost to your other bodily functions. But unless you’re doing intense exercise and sweating profusely, water is likely to be just as helpful. 

Alcohol

Pints, cocktails, spritzes. It can be hard to refuse drinks that look so refreshing and put you in a tizzy. Like caffeine, alcohol has a diuretic effect. This causes you to lose more water and steadily get dehydrated as you continue imbibing—that’s why day-drinking in the sun can really do a number on you.

[Related: Why 8 glasses of water a day is a myth]

That said, it’s still just a game of proportions. A beer will have more water than a neat whiskey, and a margarita’s dehydrating properties will depend on just how strong the bartender makes it. Your best bet is to assume booze isn’t giving you the fluids your body needs, and to drink a whole glass of water for each alcoholic beverage. You’ll stay hydrated even after you ‘break the seal,’ and you’ll avoid a hangover to boot. 

Trade a drink for a snack

Liquids aren’t your only saviour in the heat. Certain foods will also help stave off dehydration. Before a football game at Indiana, Jones makes sure that the snack selection laid out for players is going to optimise hydration levels. That means plenty of carb-rich foods, and different salty snacks such as pretzels, granola bars, and pickles (which have the dual benefits of keeping sodium levels up and making you thirsty to fuel your fluid intake). Fresh fruit, fruit snacks, and applesauce also tend to make an appearance.

When in doubt, just drink water. The liquid in our body is mostly water, and that’s what we lose when we sweat, cry, and pee. If you really can’t stand the banality of plain H2O, try and have fun with it. A sprig of mint here, a slice of cucumber there. Throw in something green or a fruit or two—anything that might make you forget that you’re not sipping on something far worse for your mind, body and soul.