Importance of hydration

Ever wanted to know the key facts about the importance of hydration? Do men need more fluid than women? How much fluid do we need to drink when exercising? This FAQ includes useful advice and answers to some of the most common questions we get asked.

• 1. How much water should we be drinking?

  The European Food Safety Authority (EFSA) recommends an intake of 2.5 litres of water for men and 2.0 litres of water for women per day, via food and drink consumption Of this, they suggest that 70-80% of the daily water intake should come from drinks, and the remaining 20-30% should come from food.
  The British Nutrition Foundation gives guidelines for the types of fluid to drink, and water is the only fluid which they recommend drinking “plenty” of as it contains no sugar, calories or additives. In spite of this, research shows we still don’t drink enough of it
  

• 2. Do men need to drink more water than women?

  Yes, the European Food Safety Authority’s scientific experts recommend an intake of 2.5 litres of water for men and 2.0 litres of water for women per day, via food and drink consumption..Of this, they suggest that 70-80% of the daily water intake should come from drinks, and the remaining 20-30% should come from food. The British Nutrition Foundation gives guidelines for the types of fluid to drink, and water is the only fluid which they recommend drinking “plenty” of as it contains no sugar, calories or additives. In spite of this, research shows we still don’t drink enough of it
  
  

• 3. Do children have different fluid requirements to adults?

  Yes, the amount of fluid a child needs depends on many factors including age, gender, weather and physical activity levels. It is advised that children should aim to drink approximately 6-8 glasses of fluid per day (on top of the water provided by food in their diet). Younger children need relatively smaller drinks (e.g. 150 ml serving).
  See the table below for the European Food Safety Authority’s recommendations for water intake for children under conditions of moderate environmental temperature and moderate physical activity levels. Note that these values include water from both food and drinks (amounts from drinks only have been estimated).
  
  

  Sex	Age group	Amount of fluid from drinks and food (litres/day*)	Amount of fluid from drinks only (litres/day**)
  Boys and girls	2 to 3 years	1.3	0.9 – 1.0
  Boys and girls	4 to 8 years	1.6	1.1 – 1.3
  Girls	9 to 13 years	1.9	1.3 – 1.5
  Boys	9 to 13 years	2.1	1.5 – 1.7
  Female	14-18 years	2.0	1.4 – 1.6
  Male	14-18 years	2.5	1.8 – 2.0

  Source: EFSA (2010)
  Adolescents of 14 years and older are considered as adults with respect to adequate water intake and the adult values apply.
  *It is estimated that 70-80% of the recommended amount of fluid comes from drinks and 20-30% from food.
  **Estimated amounts of fluid from beverages only.
  The British Nutrition Foundation gives guidelines for the types of fluid to drink, and water is the only fluid which they recommend drinking “plenty” of.  It is a good choice throughout the day because it hydrates without providing extra calories (kilojoules) or risking harm to teeth.

• 4. Can you drink too much water?

  Over-hydrating with any fluid is possible, and in extreme cases it can be dangerous, but, this is very rare. Hyponatremia results from abnormal water retention throughout the body. This reduces the blood sodium concentration, causing excess fluid to move from the blood into the tissue cells, including the brain.
  

• 5. How can you tell if you are dehydrated?

  
  Your body has special mechanisms to make sure you stay hydrated. Feeling thirsty is one of your body’s way of telling you that you need to drink more. Another indicator that we are adequately hydrated is urine colour. As a general rule of thumb,if you are healthy and well-hydrated the urine will tend to be straw-coloured, and becomes progressively darker the more dehydrated we become. Once it becomes honey-coloured this a sign that not enough water has been drunk. Urine that is dark brown in colour can indicate severe dehydration. Please note, certain medications and foods, such as beetroot, may change the colour of your urine. Mild dehydration may occur when we lose about 1 per cent of our body weight due to water restriction. Some common symptoms of mild to moderate dehydration are given below:
  

  • Constipation
  • Dark yellow or brown urine
  • Dry, sticky mouth
  • Few or no tears when crying
  • Headache
  • Increased thirst
  • Muscle tiredness
  • Sleepiness or tiredness
    • Children may be less active than usual.

  Research shows that losses of 2% or more can reduce cognitive (mental) performance.
  Note: If urine colour remains dark after increasing water intakes, medical advice should always be sought.
  

• 6. If all fluids contain water, does it matter which drinks you choose?

  Although all fluids provide water, and some also contain essential vitamins and minerals, some also provide energy (calories). These calories contribute to your daily calorie intake in the same way as those from the foods you eat. The British Nutrition Foundation gives guidelines for the types of fluid to drink, and water is the only fluid which they recommend drinking “plenty of”.

• 7. How much water should I drink when I exercise?

  Every individual is different and the amount of water needed to hydrate varies from person to person. It is important to be appropriately hydrated before commencing exercise in order to avoid getting cramp. However, avoid drinking too much or you will need to go to the toilet! While exercising, sip water at regular intervals every 20 minutes or so especially in hot weather or at high altitude. For high intensity exercise lasting more than 1 hour sports drinks or fruit juice diluted one to one with water may help extend time until exhaustion. It is also important to rehydrate after exercise, and for most people water is adequate. This is best achieved by sipping at intervals, rather than gulping large amounts at a time.

• 8. When is it appropriate to drink water for exercise?

  For most light intensity types of exercise including swimming, golf and walking, and for any physical activity lasting less than 1 hour water will rehydrate you adequately.
  

• 9. My child doesn’t like the taste of water. How can I help encourage him/her to make good healthy hydration choices?

  Children often copy their parent’s behaviour, so showing your enjoyment of water will help encourage them to drink it. Also studies suggest that a dislike of a food or drink can be overcome by repeating tastings 5 to 10 times over a two week period, however, avoid using excessive coercion or pressure to get them to drink it. Studies also suggest that giving kids tangible rewards, such as stickers, may help to encourage them to drink water or eat foods that they dislike. It is best to reward them with something that isn’t food or drink otherwise it may devalue the food or drink you are trying to get them to accept
  

• 10. When should I drink a sports drink?

  Sports drinks may only be beneficial for those undertaking regular high-intensity training and performance exercise lasting for more than 1 hour. Isotonic drinks may be appropriate if you are carrying out high-intensity physical activity, such as marathon running, cycling, competitive tennis, etc, for more than 1 hour.

• 11. How much water does your body need to lose to be dehydrated?

  Dehydration can be defined as a 1% or greater loss of body mass due to fluid loss, for example the loss of 0.8kg of body weight in a 80-kg person
  

• 12. Is dehydration more common in summer?

  We are at the greatest risk of dehydration when we are too hot or too dry, have limited access to water, or need more water than usual. Warm or dry environments, such as centrally heated homes, tend to increase our need for fluid. We can lose more fluid through sweating (due to exercise or hot climates), or by suffering vomiting and diarrhoea.
  

• 13. Does alcohol dehydrate you

  Dehydration can occur as a result of drinking too much alcohol. Alcohol is a diuretic, which means that it makes you urinate more. If this fluid isn’t replaced you may become dehydrated, so drinking alcohol should be balanced with drinking non-alcoholic fluids, such as water
  

• 14. How does water make up our body weight

  Water makes up to 60% of an adult’s and 75% of an infant’s body weight and performs crucial roles such as carrying nutrients and waste products between our major organs, helping regulate temperature, lubricating our joints and acting as a shock absorber