Four Myths About Staying Hydrated Debunked

Four Myths About Staying Hydrated Debunked

Your mum wasn’t completely wrong about the need to stay hydrated in hot weather. However, she and many others have been needlessly worrying about the wrong things. Here are four hydration myths you can safely discard.

Myth #1: Drink eight glasses of water a day does a great job breaking open this health advice snippet that everybody and their grandparents (and especially your grandparents) offer up when nearby people say they’re parched. It might have started as a reference point for the easily dehydrated, like infants and the elderly, or it might have derived from measuring IV drip output over a day. Either way, it is, at best, akin to stating that you should cook all your food to a healthy 120 degrees, just to ensure every single living thing is dead inside it; at worst, you’re over-spending on bottled water and working your kidneys a bit too hard.

Myth #2: Caffeinated beverages are ineffective at hydration

The centre for Human Nutrition released their study results after monitoring the hydration of 18 healthy men drinking water, coffee, caffeinated and caffeine-free sodas, and juices. Their results “found no significant differences” in hydration with any combination of drinks, and suggests that those who normally take in caffeine retain at least half the fluid in their coffees, Coke Zeros, or other boosters of choice. Of course, that study is based on drinking a “normal” amount of coffee by a “normal” person, and it doesn’t quite extend to alcohol – that actually produces a net loss of fluid, but that’s at a “noticeable” level after more than one drink.

Myth #3: If you feel thirsty you’ve left it too late

Some of us sit at a desk for most of our working day. Some of us get serious exercise. Some of us break a sweat just heading out to our car at noon. The one common denominator of how much water you need? Your mouth and its ability to tell you you’re thirsty. Those nutritionists and doctors who don’t believe in arbitrary fluid amounts say that drinking for thirst is fine, and that being thirsty is not “too late”.

Myth #4: Sports drinks are best for outdoor exercise

As WebMD points out, and as almost every coach we’ve ever had will tell you, plain old tap water is fine for the vast majority of sweat-inducing outdoor activities. If you’re running or undertaking another strenuous activity for an hour or more, you might consider one of those crazy-colored liquids to replace the sodium, potassium, and magnesium you’re losing through sweat – but watered-down fruit juice can often get the same trick done, and it definitely sells at a much lower mark-up.

This article has been updated since its original publication.


  • I have to agree with Brian.

    as a bonus a six-pack of good imported ales from your local costs about the same as 3-4 bottles of water from a shop / vending machine; (also most of the lower-priced water such as Mount Franklin, H2Go, Aquafina, Dasani, Vitaminwater, Veolia, etc are sourced from plain public tap water).

    the down-side is, beer along with any other alcohol will stack on the calories pretty quick especiallyif it’s full strength — and if you start the day with a workout at the gym, it might not be so great rocking up to the office with beer-breath first thing. 🙂

  • I think Russell Coight was on the right track when he talked about the amount of water you need in the outback:
    “the general rule for how much you’ll need is three litres per day, per person, per man, per degree over 25 degrees celcius, per kilometre if walking on foot, in the winter months dividing it by two, plus another litre at the end.”

  • Myth #3: If you feel thirsty you’ve left it too late

    This depends on what you are doing, i work in North WA in mining, during summer in pit temperatures hit 40+ before 8 in the morning. You have to start drinking when you get up and keep drinking otherwise you will end up in world of hurt.
    For reference on a hot day I’ll go through 15+ liters of water with no issues.

    • Wow! If you don’t mind me asking, how many toilet breaks do you make during the day as well? Or do you evaporate around 13-odd litres per day?

  • I recall hearing a doctor talking about the 8 glasses of water myth a couple years ago. He said something along the lines of “Yeah I was misquoted”. He went on to expand that we get water from all sorts of food/drink. So if you drink a glass of juice you’re getting roughly the equivalent of a glass of water, similarly if you eat an orange or have a meal you’re getting water.

    So at the end of the day from all sources it’s was equivalent to about 8 glasses of water. But the media just did the usual and took an easy to quote snippet.

    edit: I’d add that a good rule of thumb to work out if you’re getting enough fluid is “Am I peeing a lot?” and “What colour is it?” Generally if you don’t need to pee every few hours you’re probably a little under-hydrated.

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