How much water should you drink a day?
We debunk the beauty world's myths. This week: the recommended daily allowance of water
The first word in fashionable health is staying hydrated with an recommended daily allowance of 2.5 litres of water. Want great skin, clear eyes, good digestion, bouncy hair and even bouncier energy levels? Then you'll have to knock back eight glasses of H2O every single day.
Or will you? Where exactly does this magical water quota come from, and how can a one-fits-all prescription suit all shapes, sizes and lifestyles? We spoke to three experts ready to debunk the eight-glass rule.
Dalton Wong, celebrity fitness expert, and founder of 22 Training
"To say we all need 2.5 litres of water per day is a shot in the dark. There is, in fact, a better equation we use to work out our clients' basic water intake requirements: that is, to take your weight in kilos, and multiply it by 0.03 for your daily quota in litres.
But in truth, how much water we need is much more prescriptive. Your personal quota has variables: how active you are? Are you drinking a lot of coffee, or more hydrating herbal teas? How much water-based fruit and veg are you eating? In my opinion, the best indicator as to whether you're hydrated enough is still the colour of your pee; it should be straw-coloured. Any darker and you need to refuel.
And while dehydration can affect your energy levels, and in particular how well you work out, so does drinking too much - especially if you've knocked back an excess immediately beforehand, leaving it all to slosh around in your stomach while you're on the treadmill. My advice is to drink little and often, and at least 250ml an hour before exercise."
Dr. Margaret McCartney, expert in evidence-based medicine and British Medical Journal contributor
"There is no evidence to suggest drinking increased amounts of water benefits your health. Being told to drink eight glasses a day is also incredibly inaccurate - how big are those glasses anyway? We have a fantastic physiological system that is much more sensitive than any one-fits-all-water quota, it's called 'thirst'. Drinking to quench thirst is always a good idea, but drinking on top of quenching that initial sensation has no proven benefits - unless you are following specific advice from your doctor.
Besides, drinking endlessly from plastic bottles isn't healthy, and it's immoral - instead drink to satiate thirst, from a glass bottle filled with filtered tap water."
Eve Kalinik, nutritional therapist
"Our body is 60 per cent water, so I tell all my clients to drink at least one and a half litres of water a day to keep the body functioning properly. The main obstacle is usually a lifestyle issue, as we're almost becoming too busy to notice we're even thirsty, until we have that classic headache - and that's on top of the fact that we drink too much coffee, which dehydrates us. And it's not remedied by chugging back two litres at the end of the day if you haven't met your quota; too much too late keeps you up at night, just as dehydration would disturb your sleep.
But don't get fixated by your water intake - if you're eating a healthy diet full of fruit and vegetables, and herbal tea, that all counts towards your fluid intake, too. I tell clients to sip small amounts throughout the day and listen to their bodies. I'm a firm believer in that tried and tested method."