We tend to drink when we are thirsty but we also use the intake of fluids to punctuate the day and create rest breaks or time out of our busy lives. In terms of adequate hydration, many of us have been told that we need to be getting through eight glasses of water per day. Others of us rely on carrying a water bottle to be able to take sips at a regular basis. But is there any scientific basis for this drinking behaviour? Should we be constantly taking in fluid and regular intervals? To answer this question let’s look at what thirst is all about.
Thirst is really about the thickness of the blood. If the blood is too thick then the brain will create a thirsty feeling. But if the blood is not thick enough then we do not have the inclination to drink. This is all because the brain will do everything it can to prevent the loss of salt or sodium. The more we drink the more sodium we lose and this is not an ideal situation. We tend to think of salt as a dangerous substance but actually we cannot live without it and our ability to fight infections depends on it so we need to maintain a certain amount in the body for homeostasis or balance.
This alone seems to suggest that we should listen to the dictates of thirst rather than always having a drink by our side. The human body is beautifully designed to let us know when we need to drink. And when we first get that thirsty feeling we are probably only around 2% dehydrated anyway and this is not a problem.
How does the brain know when the body needs more fluid
When we lose around 10-20% of our blood volume, certain cells in the brain start to shrink and this produces the thirst trigger. At this point the best thing we can do is to drink sufficient to properly satiate and the thirsty feeling will disappear.
If we don’t drink enough then the body can take water out of the bones to maintain water balance. A second problem is that if we are thirsty and do not drink then the thirsty feeling disappears. This is because the brain cannot allow the continuous shrinking of neurones as this could cause brain damage. 80% of all headaches are caused by this problem, particularly after a night on the town. And sometimes we can even mistake thirst for hunger and we eat instead of drink. Our set point for water balance gradually lowers and cells become dehydrated.
The importance of water channels
Water needs to be actively transported into your cells through water channels known as aguaporins. These same channels also transport glucose, water and fat i.e. life saving substances that you need to survive. If there is a disturbance with this delicate system then your metabolic system is also disturbed.
Your metabolic system is the one which utilizes glucose and fat to produce energy for your cells to function. It is therefore the system that allows you to lose weight by burning fat. This is difficult to achieve if your cells are dehydrated. And so for every litre of water you lose from the body, you can compensate with storing 1 kilo of fat. In other words, when water goes out of the cell, the cell produces fat.
This can occur if you don’t drink enough fluid but also if you don’t intake water according to the dictates of thirst. On our 6 Step Plan we address this issue in one of our four pillars of health – Drink.