Drink eight cups of water a day! It’s like being sure to eat five servings of fruits and veggies a day, or get eight hours of sleep — it’s a statistic so central to leading a healthy life that we don’t question it any more. But here’s the thing: It’s not actually backed by science. And what’s more — forcing yourself to drink up, even when you’re not thirsty, could do more harm than good.
In a New York Times article published today (Aug. 24), Aaron Carroll, MD, urges readers to forget about aiming for 64 ounces and instead listen to their bodies. He’s debunked the eight-cups-a-day myth over and over, to no avail. Others have spoken out against it as well — the recommendation is “thoroughly debunked nonsense,” one doctor wrote in the British Medical Journal in 2011.
Why are we so convinced that eight cups of water a day is necessary? It’s partly due to misinformed doctors and experts, Carroll suggests, and partly due to how much we want to believe that drinking more water is a cure-all. Think back to the last celebrity profile you read — chances are, they credited their glowing complexion and trim figure to, you guessed it, drinking loads of water. Pick up a diet book and it’s likely there as well — think you’re hungry? You’re probably just thirsty. Drink water! Another commonly circulated, easy-to-believe myth: If you’re thirsty, you’re already dehydrated — Carroll says there’s “no science behind this at all.” In extreme cases, drinking too much water can lead to seizures or other serious issues.
Most people, get enough hydration from the foods they eat and the beverages they drink over the course of a day, Carroll tells Yahoo News news and finance anchor Bianna Golodryga. “There’s water in vegetables, there’s water in fruits, there’s water in almost every beverage that we drink. There’s no rational need, and no scientific need, for [64 ounces of] pure water in a day.”
That said, there are circumstances under which people may legitimately be dehydrated. It’s mostly caused by diarrhea, vomiting, or other inabilities to keep liquids down, and is signaled by a dry mouth, extreme thirst, and low blood pressure. If you suspect you may be dehydrated, contact a doctor.
But for regular, run-of-the-mill hydration, Carroll says there’s no magic number of glasses of water you should drink per day — just trust your body. “When you’re thirsty, you’re way far away from dehydration,” he says. “Just drink when you’re thirsty.”