Drinking six
to eight glasses of water a day can, we’ve long been told, boost
concentration, give us a better complexion and more energy, keep
headaches at bay, help us to detox and even curb our appetites.
As a result, many of us carry a bottle of trusty H²O with us wherever we go.
So
it may come as a bit of a surprise to find that some experts have
started calling into question the health benefits of drinking lots of
water, suggesting that consuming the recommended one-and-a-half to two
litres of it a day is far more than the body needs.
Some have even gone so far as to warn that our obsession with drinking water has the potential to cause of a range of debilitating or even life-threatening health issues.
Over the
past few years people have started reporting that they have become
addicted to drinking water. Labelled aquaholics, they’ve been lured by
the promises of better skin, a detoxed body and more energy, but soon
feel they can’t manage without regular sips of water — and feel panicky
if they have to go without for even short lengths of time.
Professor
Mark Whiteley, a consultant vascular surgeon and founder of The
Whiteley Clinic in London, is one of those experts expressing concerns
about our water consumption. He says it’s quite feasible that drinking
more water than you should over an extended period of time resets the
brain’s chemistry to expect excessive amounts of water.
So, how can drinking too much water be harmful? And how much is too much?
LOTS OF WATER CAN MAKE YOU SWEAT EXCESSIVELY
Professor
Whiteley, also an expert in hyperhidrosis (excessive sweating) is
convinced that over-hydration — drinking excessive amounts of water — is
linked to many of the extreme sweating problems his patients suffer
from; some so severe they are considering surgery to remove their sweat
glands.
One of the
first things I always ask my hyperhidrosis patients is how much they
drink,’ he says. ‘Invariably, because they sweat excessively, they tell
me they drink a lot of water to compensate. They are surprised when I
say their drinking habits could be making their sweating worse. If you
drink more water than you need to, sweating is one of the ways the body
will try to rid itself of the excess. My patients often discover they
sweat less if they drink less water.’
IT CAN CAUSE INSOMNIA
Drinking
large amounts of water, particularly at the end of the day, can disrupt
sleep, too. ‘When we fall asleep, our brains release ADH, anti-diuretic
hormone, to slow down kidney function and stop us feeling the need to
urinate during the night,’ says Professor Whitely.
If you drink
two or three glasses of water in the evening, however, all that extra
fluid working its way through your system is likely to override the
effect of ADH, fill your bladder, and have you getting up in the small
hours. It can then be difficult to fall back to sleep.’
Whiteley
recommends no fluids for two or, even better, three hours before
bedtime. If you struggle to sleep, he advises: ‘A warm bath just before
bed, which will encourage you to sweat and dehydrate slightly, will make
it less likely you will need to get up in the night.’
YOU CAN DIE OF WATER POISONING
In
2008, Jacqueline Henson — a 40-year-old mother from Huddersfield, who
was on a stringent weight-loss programme — died of water intoxication
after drinking four litres of water in the space of a couple of hours.
And
there have been other cases of people fatally ‘overdosing’ on water.
‘Drinking too much water too quickly — and we’re talking litres of water
here, rather than cupfuls — can play havoc with the delicate balance of
salts in the body,’ says Dr Frankie Phillips, of the British Dietetic
Association
‘If we drink
a lot of water in a very short space of time, the kidneys can’t remove
the excess fluid from our bodies quickly enough, and our blood becomes
more diluted than it should be, with very low concentrations of salt.
‘The
salt levels in blood and body cells are usually the same. But if the
blood suddenly becomes more dilute, it can cause cells, in particular
brain cells to swell. This can cause pressure in the skull, which can
lead to headaches, and in serious cases, hyponatraemia or water
intoxication, which can be fatal.’
SO, HOW MUCH FLUID DO YOU NEED A DAY?
Detox
gurus, personal trainers and diet authors usually suggest we should be
drinking at least two litres of water a day — sometimes as much as four
litres — but according to current NHS advice, most adult women need only
around 1.6 litres of fluids in general (rather than water,
specifically) a day, and men around two litres, to keep the body working
efficiently.
All
drinks can count towards this official fluid target — including hot
drinks such as tea and coffee, milk and fruit juices and even the water
contained in foods such as fruits and vegetables.
David
Wheeler, Professor of Kidney Medicine and spokesperson for Kidney
Research UK, says: ‘You really don’t have to drink water to keep the
body hydrated and the kidneys functioning. Fluid is fluid as far as the
body is concerned, with the exception of alcohol, which has a diuretic
effect and can dehydrate us.’
Dietitian Dr Frankie Phillips agrees. ‘Water is a good drink because it hydrates without adding calories to your diet.
‘But
a mixture of different drinks throughout the day — such as milk, which
is rich in calcium, and small amounts of fruit juice, which contain good
levels of vitamin C — is best if you want a healthy balance of
nutrients.
‘It’s
best to avoid soft and fizzy drinks, however, as these can be packed
with sugar, which is bad for both your waistline and your teeth.’
Professor Whiteley says the NHS guidelines prove that his concerns are correct.
Recent
Swedish research suggests adults leading normal lives take in around
2.5 litres of fluid a day — about 500ml of which will be metabolised
from the foods we eat, such as fruit and vegetables.
Add
a couple of mugs of tea, or coffee, perhaps the milk in a bowl of
cereal or some soup, and you will have met your daily fluid needs.
Professor
Whiteley continues: ‘You don’t need much extra, unless you are
exercising or in a warm environment, when you will sweat more, which is
why I think it is unnecessary to drink so many additional litres of
water throughout the day.’
HOW TO TELL YOU'RE DRINKING ENOUGH
The
amount someone should drink will vary slightly according to their size,
how active they are and the environment they are in. The bigger and
more active you are, the more fluids you will need. You will also need
to drink more if you are in a warm climate.
The best way
to tell if you need a drink is to go by thirst. If you’re thirsty, you
need a drink — it’s as simple as that. You can also tell if you need to
drink more or less fluids by keeping an eye on the colour of your urine.
Ideally it should be a light, straw colour. Any darker probably means
that you’re dehydrated and need to drink more.
If it’s very pale or almost clear — you are drinking too much and need to slow down a little.
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