Water is an essential nutrient, which we can get from both the fluids we drink and the food we eat.
How much water should we be drinking?
It is essential to maintain water balance, as water is an essential nutrient for life. As with everything we advise at YBP, fluid requirements are individual and there is no single recommended water intake. Factors such as gender, age, body mass, altitude, climate and of course physical activity level, all play a role in the amount of water that you should be drinking. See below for our guidelines:
- We recommend 2.5 litres of water for men per day (see our full hydration article to help estimate your ideal water intake).
- We recommend 2 litres of water for women per day (see our full hydration article to help estimate your ideal water intake).
- Eat a healthy diet full of fruit and veg. Water-rich foods include fruits, vegetables, broth-based soups, oatmeal, and beans.
- Drink little and often throughout the day.
- It is essential to stay hydrated both during and after exercise.
- Urine dark in colour and strong in odour indicates dehydration.
- Constipation can be a sign of dehydration.
- Alcohol, tea and coffee can cause dehydration.
The European Food Safety Authority (EFSA) recommends an intake of 2.5 litres of water per day for men and 2 litres for women from both food and drink combined. They recommend that 70-80% of your intake should come from drinks, and the remaining 20-30% should come from food. The Institute of Medicine recommends 13 cups (3 litres) for men and 9 cups (2.2 litres) for women per day.
Foods with high water content tend to look larger, their higher volume requires more chewing, subsequently they are absorbed more slowly by the body, which helps you to feel full. Water-rich foods include fruits, vegetables, broth-based soups, oatmeal, and beans.
Water and your body
The British Nutrition Foundation recommends drinking water, as it contains no sugar, calories or additives. Research consistently shows we still don’t drink enough.
Water has many essential functions within our body. It contributes to the maintenance of normal physical functions, cognitive functions and the maintenance of thermoregulation.
Other crucial roles include nutrient transportation to cells, waste removal from cells, elimination of toxins from body, creation of saliva, fat mobilisation, digestion and absorption. It also provides a moist environment for ear, nose and throat tissues.
It's important we constantly drink during the day as we don’t really have a water storage place in our body. It's better to drink little and often as drinking a lot all at once tends to go straight through you, as your body can only absorb a finite amount at any one time. Of course during and after strenuous activity more water will need to be consumed.
Your brain regulates water balance through the posterior pituitary gland, directing how much water should be held and how much should be excreted through the kidneys. When you are losing fluids for whatever reason it is important to listen to your bodies thirst mechanism and replenish lost water.
The kidneys filter the blood, excreting harmful toxins such as urea nitrogen, a water-soluble waste product. When you do not drink enough fluids your urine will have an odour and be dark in colour, because the kidneys trap extra fluid for bodily functions. Your urine should be light in colour and odour free.
Water helps food pass through the gastrointestinal tract, preventing constipation. When you don't get enough fluid, the colon pulls water from stools to maintain hydration, resulting in constipation. Along with adequate fibre, water will help keep your digestive system moving.
Water is also important to help maintain your skin. Your skin functions as a protective barrier to prevent excess fluid loss. Your skin contains a lot of water and dehydration can cause dry, wrinkled skin.
Water facts and figures
- An adults weight is made up of 60% water compared with 75% for an infant. Our brains are 73% water.
- Water is lost, not only through urination, but also faeces, through skin and via our breath.
- It has been shown that dehydration can reduce concentration, increase feelings of aggression and irritation, as well as reduce our cognitive and physical performance.
- Alcohol interferes with the brain and kidney communication and causes excess excretion of fluids, which can then lead to further dehydration.
- It has been shown that when a person is feeling hungry a glass of water can help satisfy the hunger signals.
- When cells are not properly balanced with fluids and electrolytes, they shrivel and become fatigued.
- Chronic dehydration may result in kidney stones.
Factors that affect water consumption
While exercising it is important to keep well hydrated, not only to prevent a drop in performance but also for your health. The American College of Sports Medicine recommends 17 ounces of fluid (0.5 litres) about two hours before exercise and at regular intervals during to replace fluids lost by sweating. If you exercise or engage in any activity that makes you sweat, you need to drink extra water to compensate for the fluid loss. An extra 1.5 to 2.5 cups (400 to 600 millilitres) of water should suffice for short bouts of exercise, but intense exercise lasting more than an hour (for example, running a marathon) requires more fluid intake. How much additional fluid you need depends on how much you sweat during exercise, and the duration and type of exercise.
If you are training for performance (not fat loss) and are training with long bouts of intense exercise, it is best to use a sports drink that contains sodium, as this will help replace sodium lost in sweat and reduce the chances of developing hyponatremia, which can be life threatening. It is also essential that you continue to replace fluids after you've finished exercising.
Hot, humid weather and heated indoor air, can make you sweat, leaving you dehydrated and in need of fluid. Altitudes greater than 8,200 feet (2,500 metres) may trigger increased urination and more rapid breathing, which use up more of your fluid reserves.
ILLNESSES OR HEALTH CONDITIONS
Illness such as a fever, vomiting or diarrhoea, increases fluid loss, requiring you to drink more water. In some cases, your doctor may recommend oral rehydration solutions, such as Gatorade, Powerade or CeraLyte. Certain conditions such as bladder infections and urinary tract stones, may necessitate increased need for fluid intake. Other conditions can impair water excretion. Heart failure and some types of kidney, liver and adrenal diseases may require that you limit your fluid intake.
PREGNANCY OR BREAST-FEEDING
Pregnant or breast-feeding woman need additional fluids to stay hydrated. Large amounts of fluid are used especially when nursing. The Institute of Medicine recommends that pregnant women drink about 10 cups (2.3 litres) of fluids daily and women who breast-feed consume about 13 cups (3.1 litres) of fluids a day. Please remember that water contained in tea and coffee is not an ideal replacement when dehydrated as they are diuretics and increase your loss of water.
Tips to increase your intake
- Drinking hot or warm water from the kettle is much easier in the winter when it is cold.
- Plain water with a slice of lemon or lime in it is a good way to change the taste.
- Starting the day with a glass of water helps flush the body of toxins built up overnight.
- Ideally buy bottled water, even better is to find a glass bottle and have a filter at home so you can refill the bottle. There are many types of filters available.
- Aim to have most of you water intake away from meals, as drinking a lot of water close to a meal may dilute digestive acids and enzymes, inhibiting digestion, although a glass of water one hour before a meal may help increase the enzymes and acids.