Let thirst be your guide when it comes to hydration, sports drinks

Rather than try to follow changing guidelines on how much to drink each day, let thirst be your guide.
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There was a time when people drank because they were thirsty. People in desk jobs didn’t give hydration much thought beyond refilling their coffee mugs. Throughout most of the 20th century, marathon runners were discouraged from drinking during exercise for fear it would slow them down, writes Dr. Timothy Noakes, professor of exercise science at the University of Cape Town and author of “Waterlogged.” Noakes notes that those athletes did just fine.

It was only during the mid-1970s, after the widespread appearance of the first sports drink — Gatorade, named for the University of Florida football team — that the pendulum swung. A recent investigation by BMJ (formerly the British Medical Journal) concluded that, in the decades that ensued, the sports drink industry promoted hydration by sponsoring scientists who advised sports medicine organizations, which then developed hydration guidelines.


Thirst quenchers: In the May 24 Saturday section, an article about hydration products said that the Bai brand of beverages has nine flavors. There are 10 flavors. Also, they are sweetened with stevia and erythritol; the article mentioned only erythritol.
Athletes were urged to drink as much as possible, before they sensed thirst. Sports drinks were encouraged for anyone who broke a sweat. And the advice trickled into mainstream culture.

“I recall that when I first came to the University of Connecticut in 1990, no one carried water into the classroom. Now one out of three students carries a water bottle,” says Lawrence Armstrong, a professor in the university’s Human Performance Laboratory. He attributes the proliferation of water-toting students to “a media concept explosion on drinking eight glasses of water per day.”


It’s not that drinking water, or sports drinks for that matter, is bad. Water is the main component of the human body, making up 60% of its mass. After three to six days without water, a person will die. Studies have shown that even mild dehydration affects mood and cognitive ability — giving credence to the eight-glasses-of-water advice, says Armstrong, who was one of the studies’ lead authors. But Institute of Medicine guidelines state that most healthy people can meet their daily water needs the old-fashioned way: by letting thirst be their guide.

And though sports drinks can offer benefits to athletes exercising at high intensities or for long periods of time, “the average person or recreational athlete doesn’t need a sports drink,” says Armstrong. The human body is proficient at maintaining homeostasis, adjusting electrolyte balance to stay within optimal range, so it’s unlikely a healthy person would hit a sodium deficit under normal conditions. Plus, the high sugar content of many sports drinks can significantly increase daily caloric intake.

Still, the nonprofit IOM estimates that adequately hydrated people drink 2.7 to 3.7 liters (about 3 quarts to a gallon) of fluids each day. (And 20% comes from food.)