Debunking Water Myths

General Medical

Dr. Sam Hay

“No man’s a camel!” is a frequent exclamation in our household. And it’s true. Water makes up over 60% of the human body, and is imperative to keep our metabolism working at its peak. We all know we need to drink to stay alive, but there’s certainly a lot of misinformation out there.

Dr Sam steps us through the 8 biggest hydration myths.

Myth: Everyone must drink 8 glasses of water a day

This is an interesting one, and the history possibly dates back to 1796!  Legend has it, that the Surgeon General to the King of Prussia, a sprightly 80 year old at the time, “enjoyed much better health than in his youth” by drinking eight glasses of water a day. But the science seems to come from the 1940s. Research at the time showed the daily requirements for water for an average adult was about two litres - eight glasses. But things got a little lost in translation, as everything we consume – fluids and food – contains water. So most people probably don’t ultimately need as many as eight glasses a day.

The truth is, everyone’s different, and every day is different. Some need more, some need less, and the exact amount changes depending on daily activities, climate, exercise, body size and weight, age, and any illnesses.

Myth: After exercise you must smash a sports drink

Exercise burns energy and water, plus sweating causes the body to lose vital salts. So whenever we do some heavy work, either pounding out the miles on the track, or working hard in the veggie patch, we must replace what’s lost – water and salts. But sports drinks aren’t the be all and end all. Sure, they’re a convenient way to deliver water, salts, and sugars; but, they’re really only a necessity for those exercising to a more extreme level (and even then they’re not completely perfect). Truth be told plenty of water, plus the salts and sugars from your next meal is all most require.

Did you know?  Beer is just as good as a rehydration fluid as a sports drink! But only in moderation.

Myth: Always have a glass of water first thing in the morning

That early morning gulp of fresh cool water is certainly refreshing, but it’s not vital for your body. The human body, and especially our kidneys, are very good at balancing water requirements throughout the day and night. There are even hormones that fly around to alter the way the kidneys work in order to conserve more water whilst we sleep.

Myth: Coffee will only dehydrate you more!

The daily cuppa is a staple for most Aussies, desperate for their little ‘kick’. But consider one after exercise and you’re sure to be met with disapproval! The myth that coffee dehydrates you is wrong. Sure, caffeine alone gets the kidneys working, but the water in your coffee or tea more than makes up for it.

Myth: If You're Thirsty, You're Already Dehydrated

Well, this is kinda true. Thirst is triggered when there’s been a reduction in the water content in the body. Normally, this sensation kicks in at around 2-4% loss of body water. Unless you’re an elite athlete, the greatest majority of us cope very well at this level of ‘mild dehydration’, with thirst being the only sign. Dehydration usually only becomes an issue for us when we lose more than about 5-8% water. By now, people start to feel head-achey, tired, or dizzy. Not to mention an even drier mouth!

Myth: You only need to drink extra when you exercise

Many people forget that a busy life, especially in hot climates burns energy and water. It’s imperative on hot days to not only avoid the heat, but replace all the extra water (and salts) your body loses trying to keep you cool.

Got the flu or feeling sick? Then you definitely need more to drink! Our immune system burns plenty of extra water fighting illness and keeping you healthy.

Myth: You can’t drink too much water!

You certainly can! Remember those salts we mentioned earlier? Well if you drink too much plain water, you dilute the body’s salts to a dangerous level (called hyponatraemia), which can lead to confusion, seizures, and death.

Myth: Water flushes toxins from the body

Ha! We’ve all tried it - after a big Christmas celebration, resorting to a water fuelled ‘cleanse’ in the days that follow, convinced it will rid us of our sins. Sorry folks, but just like the ‘liver cleansing diet’, it doesn’t work that way. The body’s natural waste management systems – the liver and kidneys – work just fine with ‘enough’ water. They don’t need any extra. In fact, the extra water diluting body salts just might prevent them from doing a perfect job.

BMedSci, MBBS(Hons), FRACGP, GDipSpMed, DCH
Director Your Doctors®


Please note: Dr. Sam's blog is general advice only. For further information on this topic please consult your healthcare professional.

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