With dangerous levels of heat blanketing several regions of the United States, hydration is more important than ever. If you’re not taking in enough fluid to produce adequate sweat on a hot day, you may be more vulnerable to heat stroke. Dehydration can be caused by extreme heat, but it can also exacerbate other heat-related conditions like heat cramps.
So taking in liquids is crucial, but hydration can go beyond simply drinking water. The popular belief that we all need to be drinking eight cups a day to be truly hydrated persists, though it has been debunked again and again.
“There’s really no data behind the eight glasses of water a day thing,” said Dr. Dan Negoianu, a nephrologist at the University of Pennsylvania. For example, “just because your urine is dark, that doesn’t prove that you’re dehydrated.”
Being hydrated simply means consuming enough fluids to the point where you’re not thirsty, Dr. Negoianu said, and that amount varies for everyone.
There are plenty of things besides plain water that will keep you hydrated, experts say: These include the foods and drinks that appeal to you, the things that will keep you consistently reaching for them. Here are a few suggestions.
Look to your favorite fruits, veggies and drinks
“We think that we need to drink a lot of water all the time because we hear that all the time,” said Tamara Hew-Butler, a sports medicine scientist at Wayne State University who specializes in fluid balance. “You gotta drink your eight glasses — hydrate, hydrate, hydrate.”
But any food or drink that has fluid content will be hydrating, she said: “Your body doesn’t care where hydration comes from, it just needs fluid.”
Fresh fruits and vegetables are ideal sources because not only do they tend to hold high water content, but they also have fiber, which provides other benefits for your diet and health. Melons, such as watermelon, honeydew or cantaloupe, are especially juicy. Strawberries, oranges, grapes, cucumbers and celery are also packed with water.
Beverages of all sorts can be hydrating. Juice, milk, tea and coffee each contain fluids that your body can use. Drinks with high sugar content may not be the best nutritional choice, but research shows that sugar-sweetened beverages are just as good as water at delivering fluids to your system. In the heat of summer, of course, frozen desserts like ice pops and sorbets are handy vessels for liquid consumption.
“You can achieve, and exceed, your daily fluid requirements through the ingestion of beverages and high moisture foods without drinking a single glass of plain water,” Dr. Hew-Butler said in an email.
Caffeinated drinks can be hydrating, too. Though caffeine is often deemed a diuretic, or dehydrating substance, research shows that consuming coffee or other caffeinated beverages has about the same hydrating or dehydrating effects as if you just drank water — especially if you’re a regular caffeine consumer.
If you’re having a significant amount of caffeine after a long period without it, you might experience a small blip of dehydration, said Kelly Hyndman, a researcher at the University of Alabama at Birmingham who studies kidney function and fluid retention. But otherwise, caffeine will not cause dehydration, she added — at least not at the levels people typically consume it.
Don’t be afraid of savory foods
You have probably heard that salty foods are dehydrating, but that is not strictly true, Dr. Hyndman said.
Our bodies are constantly looking to maintain a salt-to-water balance, which they do with the help of a number of hormones. One of the most prominent of these is the antidiuretic hormone, or ADH.
When we consume a lot of salty foods at once, our brains will secrete ADH, which in turn tells our kidneys to hold onto water, preventing us from peeing out excess fluid. The hormone is also linked to feelings of thirst, and its combined effects signal that you need more fluids. Consuming too many salty foods is only an issue if you are also ignoring your thirst cues, Dr. Hew-Butler said.
If you’re looking for savory foods that are hydrating, olives and pickles are acceptable choices, though it’s rare that people consume those in large quantities. Soup, especially with water-based broths, can also help you get your fill of water.
But what is actually dehydrating is alcohol. “Alcohol suppresses ADH,” said Dr. Hyndman. So when you consume it, “you don’t have this hormone telling your kidney to reabsorb water” and any fluids you consume will go straight through you.
Make sure kids, older adults and those with medical needs get their fill
“Most of us who say we’re dehydrated probably aren’t,” Dr. Hyndman said. While there are probably some people who are walking around a little dehydrated, she added, the majority of folks are adequately hydrated or even a little overhydrated. If you’ve complained of having a small bladder, or you’re just peeing more often than you’d like, maybe you don’t need to be consuming so much fluid — it’s just flowing through you.
Those who need to be most diligent about actively hydrating are children, older adults and people with underlying medical conditions, Dr. Hyndman said.
The rest of us simply need to have a drink or eat foods full of fluids when we are thirsty, Dr. Hew-Butler said, and trust our instincts. “We don’t need to overthink it,” she added.
“I think the ‘drink when you’re thirsty rule’ is one that’s hard to argue against,” Dr. Negoianu said, barring medical conditions or ultra-harsh environments that might cause abnormal water loss. “When it comes to the amount of water you need, it’s like Goldilocks and the Three Bears.” Just as Goldilocks had to decide for herself which porridge was just right, every person has to find the hydration level that’s just right for them and their situation.
Audio produced by Kate Winslett.
