Too much water can kill

Did you know that you can drink yourself to death? No, we're not talking about boozing here, just plain water.


Water makes up about 60 per cent of one's body weight and is needed in almost every process essential for life - regulating body temperature, lessening the burden on the kidneys and liver by flushing out waste products, and protecting body organs and tissues.


However, many people are unaware that drinking too much water during exercise in a short period of time can result in a condition called acute hyponatremia, or the dilution of the body's salt content of the blood.


This has potentially dangerous effects, like rapid brain swelling, which can result in a coma and even death.


What about the advice you read exhorting you to drink 11/2 to 2 litres of water a day? Does it mean water only or do other liquids and water content of foods count?
There has been much debate as to what should be the norm. However, the question of how much one should drink has no easy answer.


Associate Professor Fabian Lim, an exercise physiologist for the past 18 years, said that a person should depend on biological indicators such as thirst and the colour of his urine to guide his fluid intake when at rest.


A clear urine colour is ideal, added the programme director (combat protection and performance) at DSO National Laboratories, Singapore's national defence R&D organisation.
Depending on his level of activity and environmental conditions, one may require between 1.5 and 2.5 litres of fluid a day, which includes the water content in meals.


'We used to be taught to drink eight glasses a day but there is no known scientific basis for this recommendation,' said Dr Lim. 'Drinking by fixed volume is not reliable because everyone's daily fluid turnover is different.'


Research also shows that when engaged in physical activities, humans can lose up to 2 per cent of their body weight in water without physiological consequences or a compromise in performance.
Dr Lim recommends those who exercise regularly to establish a fluid loss profile.


They can do so by weighing themselves before and after exercise, then coming up with a fluid intake plan that prevents more than a 2 per cent loss in body weight during exercise. This helps to replace the amount of water lost as sweat.


Every 1kg loss in weight is equivalent to 1 litre of water.
Keeping track of the water loss is especially important in warm and humid conditions like that of Singapore, as one can lose between 1 and 2 litres an hour of sweat during intense exercise.
After working out, rehydration should also not be rushed but spread out over the next half to one hour.


'You should revert to your normal drinking habits. Drink comfortably and make sure that you don't feel bloated or feel discomforted,' said Dr Lim, who is also a member of the Singapore Sports Safety Committee.


Adding a tinge of salt to the water will also help retain it in the body.
Urine should be clear after about four hours.
Drinking lots of water too quickly will only induce urine production and does not help to replenish the water content in the body, resulting in an incomplete rehydration.
The bottomline: Drink liberally but be aware of the dangers of over-drinking.

We can lose up to 2% of our body weight in water without physiological consequences.



(taken from asiaone.com)