Hydration - An Overview



Water makes up a large proportion of the body - on average 60% of body weight in men (slightly less for women as they naturally have a higher body fat percentage).

WHY do we need water?

• Regulating body temperature
• Transporting nutrients and compounds in the blood
• Removing waste products that are passed in the urine

Water is mainly lost in urine and sweat. It’s also lost throughout the day when you breathe and when small amounts of water evaporate through the skin. To avoid dehydration, you need to replace the lost fluids with drinks and from water found in food (around 20% of our fluid intake can come from food).

The Eatwell Guide suggests 6-8 glasses of fluid per day

Do you need sports drinks when exercising?

Physical activity also increases the amount of fluid you need to consume in order to replace the water you lose as sweat. The amount lost depends on how long you are active, how intense the activity is and whether it’s hot and humid . It’s a good idea to start any physical activity well hydrated and to drink at intervals during activity. Water is fine for rehydrating after the kind of moderate exercise that most active people choose, and the majority of active people do not need special sports drinks to stay hydrated. However, for high intensity exercise that lasts more than 1 hour or so, drinks that contain some sugars and sodium (salt), such as sports drinks or homemade versions, may be better at replacing the extra fluid lost as sweat.

Does it matter which drinks you choose?

All non-alcoholic drinks can contribute to hydration and some also contain essential vitamins and minerals. However, many drinks, such as soft drinks and fruit juices are high in sugars and so contain energy (calories). These calories contribute to your daily intake in the same way as those from the foods you eat. It is also important to look after your teeth, and consuming sugar-containing drinks too often can potentially harm your teeth, especially if you don’t brush teeth regularly with fluoride toothpaste. It is also important to be aware that some drinks are acidic (e.g. fruit juice and carbonated drinks) and that this may cause dental erosion (damage to tooth enamel) if they are consumed frequently.

Drinking water is a great choice because it delivers fluid without calories or the sugars that can potentially damage teeth.

Tea or coffee can also count towards your fluid intake. Although the caffeine found in tea and coffee can make you produce more urine, so don’t solely rely on these as a main source of hydration.

  • Other hot drinks such as herbal teas, hot chocolates and malted drinks can provide water, but if these drinks are sweetened with sugar it increases their calorie content. Sugar in hot drinks also increases their potential to damage teeth if good dental hygiene is not practiced.

Milk contains lots of essential nutrients such as protein, some B vitamins, iodine and calcium, as well as being a source of water. However, it can also contain saturated fat, therefore it’s a good idea for adults and older children to choose semi-skimmed (less than 2% fat), 1% or skimmed milks.

• Fruit juices and smoothies give you water plus some vitamins and minerals… However, fruit juices and smoothies contain sugar (and therefore calories) and can be acidic, so they can potentially harm teeth. Fruit juices and smoothies should be kept to a combined total of 150ml per day as recommended on the Eatwell Guide (see earlier post)– this can count as a maximum of one portion of your 5 A DAY, but not more than this. This is because they don’t contain the fibre that is found in whole fruits and vegetables.

Sugary drinks, such as fizzy drinks, squashes, juice drinks and flavoured waters can contain a lot of sugar and generally provide few nutrients - this adds to your calorie intake and, as mentioned earlier, the sugar can potentially damage teeth if the drinks are consumed frequently. It’s a good idea to limit or avoid consumption of sugary drinks and swap them for diet, sugar free or no added sugar versions. Energy drinks, (Monster, Red Bull) are similar and contain added caffeine.

Alcoholic drinks have a diuretic effect, that is, the cause you to lose more water in urine, so drinking alcohol may lead to dehydration. It is important to keep alcohol consumption within the recommended limits (no more than 14 units per week for both men and women). Alcoholic drinks contain calories so it’s important to be aware that these will contribute to your calorie intake, for example, a standard (175ml) glass of 12% wine contains about 126kcal and a pint of 5% lager contains about 215kcal.


Good post. I always hav problems drinking enuf water, partly cos i find it boring, partly cos am not a big drinker in general (not even juice or pop or owt) and partly cos i feel like itll bloat me up n cause more weightgain. I usually dont even bring water 2 the gym. But iv been told the bloating thing is just a myth n long term water can actually help weightloss if ne thing