Most people tend to drink too little fluid. Especially when it is cold, many forget to replenish the body's fluid balance in between. Many also know the rule of thumb to drink 2 litres of water a day to avoid dehydration, but different body statures, weights and activity levels mean that the actual amount of water needed varies significantly. So how do you calculate what amount of water is optimal for an individual?

 

 

Why is water so important for the body?

 

The human body consists of 60 to 70% of water. This water is required for the production of saliva, digestion, the function of the body's organs and the transport of oxygen in the blood. 

If you lose even one per cent of your body weight in the form of water, symptoms such as tiredness, headaches, palpitations and the ability to maintain body temperature become noticeable.

 

 

Water loss and water intake per day

 

The body loses water through urination, sweating and normal bodily functions. This water must be replaced by food and fluids. 

 

Fluid is not only absorbed in the form of drinking water, but also through all foods that contain water, such as dairy products, soup and fruit.

Caffeinated drinks such as coffee, soft drinks and tea should not necessarily be counted as good sources of fluids, as they have a diuretic effect and help to excrete water from the body.

 

Of course, juicy fruits such as citrus fruits contain a lot of water, whereas bananas, for example, contain relatively little water.

 

Photo: D Sharon Pruitt

 

How much water everyone should drink per day

 

In general, you should drink 25ml of water per kilogramme of body weight per day, with men needing more water than women. A man weighing around 80kg should drink 2 litres of water or 13 glasses (150ml each) on a mild day without any particular physical activity. A 70kg woman should drink one and a half litres of water or 9 glasses a day. If physical activity and heavy sweating are added to this, two to three glasses of water should be added.

 

So the basic rule for the average day without sweating is:

 

Men: 25ml of water per kilogramme of body weight

 

 

Women: 20 to 22ml of water per kilogramme of body weight.