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The Importance of Hydration
We all know that water is essential for life. Adult humans contain a high degree of water; for example a 75kg man with low body fat may contain in the region of 48.5kg of water, or 65% of his total body weight.
When considered in these terms we can see why it is so important for health to maintain hydration. We not only obtain water by drinking it, but also from other beverages consumed and from food – and we lose water through sweat and waste products.
Maintaining a safe level
The question remains, therefore, what do we need to consume to maintain good hydration? Public Health England’s Eat Well Guide recommends drinking 6 – 8 glasses of water or low fat/sugar free beverages a day, but does not qualify the size of glass. Other sources of publicly available information suggest monitoring the colour of urine, but give no indication of daily fluid requirements. So in essence, the advice given can be vague and hard to follow.
It is acknowledged that health problems can arise through dehydration from impairing performance and cognitive function to more serious heat related illness. Research has also established that age and gender affect hydration status, with women and older adults being more susceptible to fluid imbalances. Therefore, a useful life-skill to have is the ability to accurately assess your own hydration status.
Science tells us that as little as a 2% loss of body weight through dehydration is sufficient to impair performance, which results in increased strain on our cardio vascular system, heat strain, alterations to the central nervous system and metabolic functions. Initial symptoms of dehydration might include headaches, tiredness and difficulty in concentrating – all of which are likely to affect performance, both in daily living, at work and when exercising.
There are a number of easy steps we can take that will be helpful to us to monitor our hydration. If active, get used to weighing yourself before and after exercise (naked if possible, if not, then wearing the same clothes). The deficit in body weight during exercise will be largely due to losing water through sweat. In order to compensate for this loss you will need to drink about 150% of the amount of weight lost.
Little and often
It is equally important that this fluid be consumed over a period of time i.e. 60 – 120 minutes, as when we drink a high volume of liquid it passes quickly through our system without being used to rehydrate our body. This approach can also be used overnight as high volumes of fluid are lost through sweat when we’re asleep, especially in the summer.
Some of us will produce more salty sweat than others. Whilst it may have a bit of a ‘yuck’ factor, the simplest way for you to test this is to lick your own fresh sweat! If you think that your sweat is particularly salty, drinks containing electrolytes will help your body to rehydrate more efficiently. You don’t need to buy expensive sports drinks for this, but can make your own by simply adding sugar and salt to water.
Also be aware of the colour of your urine; A body that is well-hydrated produces copious amounts of pale coloured urine, but be mindful that drinking a high quantity of fluid quickly can also have this effect giving a false indication of hydration and that consuming alcohol can also give rise to frequent urination.
Caffeine often receives a bad press as being diuretic, but for most people, especially the many of us who are used to regularly consuming caffeinated beverages caffeine, will have a negligible effect on hydration. We just need to be wise to frequency of urination and colour of urine. Straw colour or a pale yellow is optimum and what we have consumed both in terms of fluids and food.
Remember that the feeling of thirst is often the first sign that we are already dehydrated.