I grew up in Sri Lanka, a tropical country where it was pretty hot during the day and we perspired a lot. But we did not pay too much attention to staying hydrated by drinking water all the time. Furthermore, in middle class homes like mine, there was the belief that tap water was not pure enough to drink and could contain dangerous bacteria and so in our home water was first boiled and then cooled in the refrigerator. We did not drink water outside the home unless we were in another middle-class home that followed the same practice. We drank water with meals and two or three cups of tea and/or coffee during the day. As younger schoolboys we would take a little canteen of water with us to school but as we got older, we stopped doing that and simply did not drink water until we got home. If we got thirsty drank hot tea or coffee or bought a bottled drink, bottled water not being a thing then. When we played sports as children during the blazing hot days, we would of course get thirsty and would drink water when we felt the need.
It was only after coming to the US that I saw people do ‘preventive drinking’ of water, also known as ‘staying hydrated’ and then later people started carrying around water bottles with them and made it a point to drink from it regularly, even though they were living in a mild climate and were not exerting themselves. The fear of becoming dehydrated had become pervasive and Tamara Hew-Butler, a professor of exercise and sports studies at Wayne State University (academic departments are becoming so specialized these days!) warns that people, especially those in charge of sports programs for young people and athletes, are carrying this too far and ignoring the opposite, but very real, danger of ‘overhydration’ that can lead to hyponatremia and even result in fatality. She recommends that people should return to the practice that I followed as a boy and still follow as an adult, and drink when they get thirsty.
Turns out, the neuroendocrine thirst circuit dates back 700 million years and is found in most animals, including bugs and worms. Thirst activates the same conscious area of the brain that tells us we’re hungry or have to pee. To say we need to stay “ahead of thirst” (or die) is like saying we need to pee every hour to stay ahead of imminent bladder explosion (or die). The molecular and neural circuits that govern fluid intake (and micturition) in real-time are absolutely exquisite.
It’s remarkable to think that animals survive without water bottles and urine charts – they drink when they are thirsty, and we should too.
Hyponatremia is caused by drinking too much water or sports drinks, which dilutes blood salt levels below the normal range. Any sudden drop in blood salt levels, from drinking more than the body can excrete, can cause all cells in the body to swell. Brain swelling from hyponatremia can cause headaches and vomiting, while muscle cell swelling can trigger whole-body muscle cramping.
What is most frightening, however, is that these symptoms mimic those of dehydration They are often treated by medical staff with more fluids.
Drinking when you are thirsty is not “too late,” because the thirst mechanism is hardwired into the nervous system to protect against scarcity.
Then, what about the need for eight glasses of water per day? There is no evidence to support this. What about peeing until our urine is clear? Dark colored urine merely reflects water conservation by the kidney, rather than water lack by the body.
She points out that we should not ignore, of course, the pernicious influence of the bottled water industry that has persuaded people that tap water in the US is not as good as their product and also urged us to drink a lot of it.
We should recognize who the “true champions” may be with regards to most modern day hydration advice. According to the latest figures, bottled water sales have increased to US$18.5 billion dollars, up 8.8 percent from the previous year. This revenue does not include the vast array of purified, infused, oxygenized, sparkled, distilled, intravenous and reverse osmosis versions that compete for attention on the market.
In addition to being a waste of money, it causes a huge amount of plastic pollution and depletes the ground water resources of many communities.
At one point, I too bought into the now-discredited idea that we must drink eight glasses of water a day and that drinks like juices and coffee and tea should not count towards this total. But I just could not keep it up. It made me feel bloated and uncomfortable and require going to the bathroom frequently, which was a nuisance. So I reverted to my earlier behavior. I know pretty much exactly how much fluid I drink a day: One cup of coffee with my breakfast, one cup of tea in the late afternoon, and a glass of water with lunch and again with dinner, with an extra glass thrown in now and then on days when I feel thirsty. This is only about half the purported requirement. Of course, I lead a very sedentary life. And people vary in their needs. Other people may well need more fluids, especially those who exert themselves a lot or are in extreme and unusual situations,. But for most people, drinking when you get thirsty seems to be the recommended policy.
The advice to practice moderation seems very applicable here.