Water is probably the one nutrient people tend to forget when they are talking about nutrition and that although no other nutrient needs to be consumed in such large amounts as water. We need each day about 50 times more water than protein. This explains quite well why humans can survive for relative long times missing out one or some of the other nutrients yet being deprived of water in your diet could lead to death within only a few days. Just one day of insufficient water intake can change the body’s metabolism.

More than half our body weight is made up by water. However water in the body is not only water in the sense of liquid much of the water in our bodies is incorporated into chemical structures that form cells, tissues and organs. Water is indispensible for the functioning of our body because it is the transport vehicle for all nutrients and waste products. Almost all nutrients dissolve readily in water and fatty substances are transported with the help of water soluble proteins. Water also acts as a lubricant and cushion for our joints, our brain, our eyes and the spinal cord.

Most of the water is lost through the skin and other losses occur through breath, urine and faeces. It is also important to note that the amount of body water varies by as much as several pounds at a time, salty foods can temporarily increase the body water content and alcoholic or caffeine rich drinks can lead to excessive water losses which would show up on the scale.

Water needs vary accordingly widely and depend on the foods a person eats, the temperature and humidity of the persons surrounding, the persons activity levels and health status. Yet dehydration has been shown to influence not only our physical performance but also our mental performance, hence good hydration may benefit your ability to work and to do sports.

Interestingly however in some sports temporary dehydration could actually be beneficial as has been shown in many studies. So for example athletes who are performing running sprints, jumping tasks and strength exercise where the body weight plays a key role could become ‘easier’ if the water loss equals body mass losses of 3-4%. It is assumed that here the reduced body weight which happens alongside dehydration enables better performance.

However if endurance exercises are performed water loss of above 3% body weight appear to be detrimental for performance. This range of dehydration is also associated with decreased performance in skills based sports (e.g. soccer, football, rugby, basketball …) as the low water content in the body appears to influence cognitive function, mood and mental alertness.

Although as mentioned dehydration might be of benefit in some sports and may provide an advantage in competitions yet long-term water loss and permanent dehydration can cause serious health risks ranging from urinary tract infections, kidney and gall stones to cancers such as bladder and colon cancer. Therefore being well hydrated is not only important for someone’s day to day performance but also for their long term health.

Unfortunately thirst perceptions gradually decrease with age and often thirst is judged as hunger and most importantly thirst lags behind the lacks of water. This means almost everyone will encounter moments of dehydration almost on daily basis  to prevent and reduce the detrimental impact on our health we should aim to drink plenty of fluids and avoid large amounts of diuretics such as alcohol and caffeine.

The best way observe your hydration levels is to check the colour of your urine regularly, it should be pale yellow almost clear throughout the day. The Foods Standards Agency recommends drinking about 2 litres of water per day, however if you exercise you should add about 1 litre for every hour of exercise and even more if temperatures are above 20-21 °C.

Andrea Zick, Esteem Fitness Nutritionist London
Esteem Fitness – Personal Training London and the South East