The average adult body is composed of 60 per cent water. Water plays a role in virtually every body process and function, from serving as a building block of cells, to acting as a temperature regulator, to flushing toxins from the body.
We feel thirsty when osmoreceptors in the brain sense a reduction in cell volume in the body. These osmoreceptors are very sensitive, meaning that the deficit of water in the body is usually minimal upon a first pang of thirst. In fact, the onset of thirst may be a response of a reduction of only 1 per cent of overall body water.
Losing water can significantly impair performance. This is particularly important during the summer months, on big climbs or wherever you tend to sweat a lot.
Dehydration can be detrimental if you lose as little as 2 % of your body’s water content. In a long endurance race, it’s not uncommon for athletes to lose up to 6-10 % of their water weight via sweat. This can lead to insufficient body temperature control, reduced motivation, increased fatigue, and mental weakness.
As unlikely as it sounds, drinking water can actually help you lose excess body fat. It can increase satiety and boost your metabolic rate.
A study has shown that drinking 2 liters of water every day can increase your total energy expenditure by up to 96 kcal. For maximum effect you have to not only drink enough but also time your water intake right. Drinking water half an hour before meals is the best, that way it doesn’t interfere with digestion but makes you feel more full, so that you eat a bit less. Drinking cold water can also be beneficial, because the body has to use additional energy to heat the fluid to body temperature.