The summer solstice has only just arrived, but there’s no mistaking the season: A heat wave has been smothering swaths of the Northeast and Midwest this week, with temperatures smashing records in cities throughout New England and Maine. Though these spots will get some relief this weekend, the National Weather Service forecasts continued highs in the 90s and above across the Ohio Valley to the Mid-Atlantic—and of course, months of summer stretch ahead for us all. So there’s no time like the present to brush up on the best way to rehydrate yourself when you’re quite literally baking.
While there’s no magic number of glasses of water we should all drink in a day (given we’re different sizes and have varying diets and levels of physical activity), one thing is certain: “We need to drink more water when we spend time in hot environments, which cause us to lose water [in our bodies] through sweating,” Riana Pryor, PhD, ATC, the director of the Hydration, Exercise, and Thermoregulation (HEAT) Laboratory in the Center of Research and Education in Special Environments at the University of Buffalo in New York, tells SELF.
That means learning the best way to rehydrate your body in the heat is key to having a cool (not cruel) summer.
First, let’s discuss why it’s crucial to stay hydrated in high temperatures.
Like many good things in life, hot weather is best in moderation. I adore a beach day as much as the next person, but the truth remains that too much exposure to heat raises your risk for heat illnesses, like heat cramps, heat exhaustion, and heat stroke, “which happen when someone’s core body temperature rises due to being in a hot environment and many times are associated with fatigue from physical activity in the heat,” Dr. Pryor says. (The double whammy of high temps and exercise makes it extra important to hydrate during and after a workout.)
But even if you’re just chillin’ on a blanket in the park or putzing around a festival, if you’re catching any rays, you need to be hydrating to avoid other heat-related conditions, like heat edema (or swelling of the hands and feet) and heat syncope (or fainting), Dr. Pryor says. With the former, the natural expansion of your blood vessels in hot weather eventually causes blood to pool in your extremities (thanks, gravity). And with the latter, a drop in blood volume triggered by fluids lost to sweating makes it tougher for your heart to maintain your blood pressure, causing you to feel dizzy or nauseated and ultimately to pass out.
The good news is, you can steer clear of these scenarios by staying hydrated before and during any adventures in the heat. Again, there’s no exact amount of water each person needs, but if you’re sweating outside, you can aim for a cup of water every 20 minutes to be safe, according to the Centers for Disease Control and Prevention.
It’s easy to lose track of time, though, if you’re having fun in the sun—maybe you’re dancing at an outdoor concert or zeroed in on a sporting event—and wind up dangerously close to heat illness. That’s when it’s essential to focus on rehydrating swiftly.
Here’s the best way to rehydrate if you’re on the verge of overheating.
Your best bet is to find an air-conditioned building, but if that’s inaccessible, a covered spot, say, under an umbrella or cabana-esque structure at the beach or park will be a better option than anywhere in the direct blaze. This allows you to cool down a bit, which can help reduce the heat’s stress on your body and slow down dehydration.
If you can feel pressure in your fingers or toes (or your rings feel tighter than usual), Dr. Pryor suggests lying down in the coolest place you can find, lifting your hands and feet, and then wiggling them around to reduce the swelling. And she has similar advice if you’re feeling faint, dizzy, or nauseated: Sit or lie down on the ground (again, ideally somewhere shady), and elevate your feet above the level of your heart to help increase your blood pressure.
Being on the precipice of any kind of heat illness isn’t something you should deal with alone—especially because some heat conditions can leave you feeling mentally fuzzy and physically weak. By informing a friend who’s with you or calling up one who’s nearby, you’re enlisting someone who can keep an eye on you and step in to help if things go south and you need medical attention, Lauren Manaker, RDN, a Charleston-based registered dietitian, tells SELF.
You knew this one was coming: The best way to rehydrate obviously includes consuming lots of water. While, again, it’s best to drink water throughout the time you spend outside (not to wait until you feel extremely hot or thirsty), if it gets to the point where you need to rehydrate fast, taking small sips more frequently or large gulps less frequently can work, Dr. Pryor says. Research that she and her team conducted found that both methods are about equally rehydrating, “and you should drink according to what is most comfortable to you,” she says.
So long as your thirst remains unquenched, you should continue drinking, since that’s a sign that you’re still at least somewhat dehydrated, Dr. Pryor says. (You’ll want to take a break, though, after downing about a half liter in one sitting, she adds, in order to avoid the discomfort of filling your stomach with fluid.)
It’s also worth noting that warm, cool, and cold water all work here. “Once it is in your body, the temperature of the fluid equalizes to the temperature of your stomach rapidly,” Dr. Pryor says. So, just choose whatever option will help you get those fluids down easily.
“To electrolyte or not to electrolyte” is a common conundrum in hydration land. On the one hand, when you sweat, you lose electrolytes that are essential for muscle function and balancing fluid levels in your cells—primarily sodium (salt), but also chloride and potassium, among others. But on the other hand, not everyone loses enough of these minerals while shvitzing (or even dripping) to justify replenishing them via an electrolyte packet or premixed drink. After all, most people regularly eat enough electrolyte-rich foods (like avocado, banana, and spinach) to still be okay with some losses due to sweat.
The main scenarios where you should swig an electrolyte bevvy involve pumping out a ton of sweat: You’re totally drenched from your time in the sun, you’ve been physically active and sweating for more than a couple hours straight, or you’re spending consecutive days outside in a heat wave (hello, festival season). At this rate, you’re likely to have a real electrolyte deficit, and filling that gap could help your body absorb the fluids you’re drinking and rehydrate more effectively.
You might also want to sub an electrolyte drink for water if you’re a salty sweater, says Dr. Pryor, which means you lose more than the average amount of sodium when perspiring. (This can also happen while your body is adjusting to the heat at the beginning of the summer, she adds.) That might be you if you notice white, crusty lines on your arms, legs, or clothes when you get hot, especially after exercise; or your sweat tastes super-salty or stings your eyes.
Counteracting some of that essential sodium lost to sweat can be as simple as munching on pretzels, peanuts, popcorn, or string cheese. In fact, a 2010 review of studies assessing hydration status in pro athletes noted that plain water can allow for “effective” recovery post-exercise so long as you combine it with salty food. Not to mention, these snacks “can also improve your hydration by encouraging you to drink more water,” Dr. Pryor says.
Also, if you’re craving any of these foods while experiencing a real scorcher of a day, that could be another sign that you’re a salty sweater, Dr. Pryor adds, and it’s in your best interest, hydration-wise, to satisfy those desires.
There’s a reason watermelon can be so dang appealing on a steamy day: It’s roughly 92% water, Manaker says. And any liquid you soak up from eating a slice or two certainly counts toward your overall hydration, helping you replenish lost fluids more quickly (and more deliciously!) than just sipping water alone.
The same thing applies to other foods with high water content, Manaker says—like cucumber, celery, cantaloupe, and tomatoes, for starters. Pair any of them with a salty topper or dip (say, hummus or peanut butter), and you’ll have a hydration-electrolyte one-two punch.
An annoying truth: Good rehydration requires avoiding the things that dehydrate you, too—like these two substances, Dr. Pryor says, both of which can act as diuretics, turning fluid in your body into pee more rapidly. That doesn't mean you have to give up frozé or iced lattés completely this summer. But if you’re out in the sun, and you feel like you’re overheating, it’s a good idea to set aside anything alcoholic or caffeinated and swap in another drink instead. (If you go for a mocktail, just keep an eye out for the sugar, Manaker says, which can pull water into your GI tract, leading to further dehydration.)
In terms of the booze, limiting your total number of drinks (no more than one or two a day is a good benchmark for most people) can also help you maintain your mental clarity, Manaker says, which is key for noticing when you might be creeping toward heat illness—and taking action to rehydrate yourself—in the first place.
A word of caution: If you’ve done everything on this list, and you’re still feeling unwell after about an hour (say, you’re really lightheaded or your cramps aren’t letting up), or you can’t keep fluids down, that might mean you’re not rehydrating quickly enough, and you should seek medical attention. Otherwise, following the above advice to get back to a healthy hydration baseline will help you take the heat in stride this summer.
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