Drinking too much can be even worse

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.

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.